THE UNIVERSITY OF TEXAS PUBLICATION NUMBER 5704 FEBRUARY 15, 1957 Pelecypoda from the Type Locality of the Stone City Beds (Middle Eocene) of Texas H. B. STENZEL, E. K. KRAUSE, AND J. T. TWINING BUREAU OF ECONOMIC GEOLOGY THE UNIVERSITY OF TEXAS, AUSTIN JOHN T. LONSDALE, Director Publications of The University of Texas COMMITTEE ON PUBLICATIONS L. u. HANKE H.Y.McCowN c. L. CLINE A. MOFFIT J. R. D. EDDY c. P. OLIVER J. T. LONSDALE B. E. SHORT S. A. MAcCoRKLE J. R. STOCKTON C. T. McCORMICK F. H. WARDLAW ADMINISTRATIVE PUBLICATIONS AND GENERAL RULES H. Y. McCowN c. H. EADS J. G. AsHBURNE F. H. GINASCOL M. v. BARTON B. GONZALES c. E. LANKFORD The University publishes bulletins twice a month, so numbered that the first two digits of the number show the year of issue and the last two the position in the yearly series. (For example, No. 5701 is the first publication of the year 1957.) These bulletins comprise the official publications of the University, publications on humanistic and scientific subjects, and bulletins issued from time to time by various divisions of the University. The follow­ing bureaus and divisions distribute publications issued by them; communi­cations concerning publications in these fields should be addressed to The University of Texas, Austin, Texas, care of the bureau or division issuing the publication: Bureau of Business Research, Bureau of Economic Geology, Bureau of Engineering Research, Bureau of Industrial Chemistry, Bureau of Public School Service, and Division of Extension. Communications con­cerning all other publications of the University should be addressed to University Publications, The University of Texas, Austin. Additional copies of this publication may he procured from the Bureau of Economic Geology, The University of Texas, Austin 12, Texas E •r •~ n i .. •­ • 0 'C 'a 0 G. • ,, - ID ,. •.... THE UNIVERSITY OF TEXAS PUBLICATION NUMBER 5704 FEBRUARY 15, 1957 Pelecypoda from the Type Locality of the Stone City Beds (Middle Eocene) of Texas H. B. STENZEL, E. K. KRAUSE, AND J. T. TWINING BUREAU OF ECONOMIC GEOLOGY THE UNIVERSITY OF TEXAS, AUSTIN JOHN T. LONSDALE, DirectQr The benefits of education and of use/ul knowledge, generally diffused through a community, are essential to. the preserva· tion of a free government. SAl\i llousToN Cultivated mind is the guardian genius of Democracy, and while guided and controlled by virtue, the noblest attribute of man. It is the only dictator that frecnien acknowledge, and the only security which freemen desire. MIRABEAU B. LAM.AR PUBLISHED BY THE UNIVERSITY TWICE A MONTH. ENTERED AS SECOND­ CLASS MATTER ON MARCH 12, 1913, AT THE POST OFFICE AT AUSTIN, TEXAS, UNDER THE ACT OF AUGUST 24, 1912 Contents PAGE ~l>stra.ct --------------------------------------------------------------------------------------------------------------------------7 l11tr<>cl11cti<>11 --------·---------------------------------------------------------------------------------------------------------]_()1() L<>ca.ti<>11 ---------------------------------------------------------------------------------------------------------------­11 IIist<>ry -----------------------------------------------------------------------------------------------------------------­18 Stra.tigra.J>liy -----------------------------------------------------------------------------------------------------------------­18 li'<>r1I1a.ti<>11s -----------------------------------------------------------------------------------------------------------­DescriJ>ti<>11 <>f tlie secti<>11 exp<>secl a.t St<>11e City Bluff ---------------------------------------2() Pa.leoec<>l<>gy a.11d sedimenta.ry e11vir<>11ments _____________________________________________ -----------_____ _ 26 26 Stra.tifica.ti<>n ---------------------------------------------------------------------------------------------------------­31 Sa.li11ity -----------------------------------------------------------------------------------------------------------------­ 32 ~~ra.ti<>11 ---------------------------------------------------------------------------------------------------------------­33 De1>tli ---------------------------------------------------------------------------------------------------------------------­ Wa.ve a.11cl current a.cti<>11 ____________________________ .___________________ -------------------------______________ _ 34 34 ()yster reefs -----------------------------------------------------------------------------------------------------------­35 Sy11tliesis ---------------------------------------------------------------------------------------------------------------­ Pa.le<>11t<>l<>gic J>r<>cecl11res _____________________________________________________________________________________________ _ 38 List <>f 11ew 11ames _______________________________________________________________________________ -,-----____________ 41 Creclits a.11cl ack11<> wIeelgments -------------------------------------------------------------------------------42 Systema.tic clescriJ>ti<>ns _______________________________________________________________________________________________ _ 43 Class Pr<>t<>l>ra11cliia ____________________________________________ -----------------________________________________ _ 43 43 Family ~11c11lidae -----------------------------------------------------------------------------------------­46 Family ~ucula.nicla.e -------------------------------------------------------------------------------------­55 Class Filil>ra11cliia -------------------------------------------------------------------------------------------------­55 Fa.IIlily ~rcidae ---------------------------------------------------------------------------------------------­ Family Glycymeridiclae _______________________________________________________________________________ _ 59 61 FaIIlily ~<>etiiclae -----------------------------------------------------------------------------------------­ Class Pseuclola.rnellil>rancliia _______________________________________________________________________________ _ 73 Family Mytiliclae __________________________________________ ----·-----_. ____________ ._________ .____________ _ 73 Fa.IIlily Pin11iclae --------------------------------------------------------------------------------------------78 8() Fa.IIlily Pteriiclae -------------------------------------------------------------------------------------------­1.i'aIIlily ~Illusiiclae ----------------------------------------------------------------------------------------82 Family LiIIliclae --------------------------------------------------------------------------------------------86 Fa.1I1ily Ostreiclae _____________________________________ -__ --------------------------------------------------9]_ li'aIIlily ~11orniida.e ----------------------------------------------------------------------------------------97 Cla.ss Eula.mellibra.ncliia. _______________________________________________________________________________________ _ 101 IC'a.I11ily C:::a.rcliticlae ----------------------------------------------------------------------------------------101 1.i'aIIlily DiJ>loclo11ticlae ---------------------------------------------------------------------------------­115 IC'aIIlily SeIIleliclae -----------------------------------------------------------------------------------------­118 Fa.111ily ~elli11idae -----------------------------------------------------------------------------------------­120 Famllv Ma~tritl11P. 1 ?.4 Family VeneI"idae -----------------------------------------------------·------------------------------------l.~~ Family J>holadomyidae --------------------------------------------------------------------------------l.61. Faml.ly Corbul1.dae ----------------------------------------------------------------------------------------1.65 class Septl.branch1·a ----------------------------------------------------------177 Faml. ly Vert1·cord1·1·dae ----------------------------------------------1.77 STATISTICAL ANALYs1s OF VoKESULA SMITHVILLENSIS (HARRIS) , by John T. Twining ________________________________ --------------------------------------------------------------181 Bibliograph}" ------------------------------------------------------------------------------------------------------------------187 Index ------------------------------------------------------------------------------------------------------------------------------197 Illustrations PLATES PAGE 1. Stone City Bluff seen from across the Brazos River ---------------------------Frontispiece 2. Vertical aerial photograph of Stone City Bluff-----------------------------------Facing p. 10 3. Basal conglomerate of the Wheelock member of the Cook Mountain formation and cannon-ball concretions in the Stone City beds ________ Facing p. 1% 4-22. P elecypods --------------------------------------------------------------------------------------------------197-215 FICURES­ 1. General location map ------------------------------------------------------------------------------------12-13 2. Topographic map of Stone City and vicinity------------------------------------------------lti-17 3. Diagram of the stratigraphic relationships ------------------------------------------------------19 4. Profile of Stone City Bluff ____________________________________________________________________ Facing p. 24 5. Atrina fragilis (Pennant) in its natural attitude in the sediment____________________ 26 6. N otocorbul,a gibba (Olivi) in its natural attitude in the sediment__________________ 27 7. Tellina tenuis da Costa in its natural attitude in the sediment__________________________ 28 8. Spiral burrow from the top of bed (s) of the Stone City beds ________________________ 30 9. Inside view of a valve of Glycymeris staminea (Conrad) ------------------------------61 10. Outline of M auricia ----------------------------------------------------------------------------------------77 11. Outline and cross section of Atrina cawcawensis (Harris) ----------------------------79 12. Outline of Pteria ____ ___ _____ ____ ____ _____ ________ ____ ___ ____ _________ _____ __ __ _______ _____________ _____ ___ ______ 81 13. Outside view of a left valve of Cubitostrea sanctiaugustini Stenzel &Twining 93 14. Allomorphic sculpture of Anomia acquired from a V enericardia substratum 98 15. A young Anomia ephippwides Gabb on a V enericardia (Venericor) ____________ 99 16. Hinge features of Venericardia (Venericor} plan-icosta Lamarck__________________ l.02 17. Hinge features of Venericardia (Claiborn-icardia) alticostata (Conrad) ______ 105 18. Hinge features of Dipl,odonta (Dipl,odonta} petropolitana Stenzel________________ l.16 19. Hinge features of Abra (Abra} petropolitana Stenzel____________________________________ 118 20. Hinge features of Kymatox praelapidosus Stenzel & Krause____________________________ 124 21. Hinge features of Katherinella smithvillensis Stenzel &Krause______________________ 135 22. Hinge features of Katherinella trinitat,is Stenzel & Krause________________________________ 137 23. Hinge features of Pitar ( Pitar) tumens (Gmelin) -----------·----------------------------140 24. Hinge features of Pitar (Cal,pitaria) parisiensis (Deshayes) ------·-----------------142 25. Hinge features of Rhabdopitaria astartoides (Julia Gardner) ----------------------152 26. Hinge features of Sinodia (Sinodia} eocaenica Stenzel & Krause ----------------159 27. Hinge features of Caryocorbula a/,abamiensis (Isaac Lea) --------------------------166 28. Scattergram of five populations of Vokesula smithvillensis (Harris)____________ 182 29. Frequency curves of five populations of Vokesula smithvillensis (Harris)____ 183 30. Expected limits of variability in the spacing of the ribs of Vokesula smithvillensis (Harris) ___ ______ _______ _______ ______ __ ____ _______ ____ __ __________ __________ ______ ______ ___ __ 184 31. Limits within which the means of the populations of Vokesula smithvulensi~ (Harris) are expected to fall ----------------------------------------------------186 Tables TABLES­ 1. Oligocene and Miocene stratigraphic units ---------------------------------------------------36 2. Paleocene and Eocene stratigraphic units ------------------------------------------------------37 3. Distribution of the Pelecypoda of the Stone City beds at Stone City Bluff _____________________________________________________________________________________________Facing p. 180 4. Variability data of Vokesula smithvillensis (Harris) and its subspecies________ 185 Walter Scott Adkins 1890-1956 While this publication on paleontology and stratigraphy was being printed, Walter Scott Adkins, one of the leaders in this field and long associated with the Bureau of Economic Geology, died at his home in Austin, Texas, Sep­tember 22, 1956. It is appropriate, therefore, to dedicate this volume to his · memory and to recognize his great contributions to geology. 0 Adkins was a native of Tennessee-and received the B.S. degree from the University of Tennessee in 1910. He did graduate work at Columbia Uni­versity 1912-1913 and 1915-1916, ·specializing in zoology and paleontology, 0 A more complete biography including a bibliography will appear.in the Proceedings of The Geological Society of America. and at the University of Paris ( Sorbonn~) 1925-1926. He held a Guggenheim Fellowship to the British Museum of Natural History 1931-1932. He joined the staff of T<•xas Christian University in 1913 and commenced his long and dedicated study of Cretaceous paleontology and stratigraphy of Texas and the Southwest, which was interrupted only by his death. He first joined the staff of the Bureau of Economic Geology in 1919. He was with the Aguila Company in Tampico, Mexico, 1921-1925, and again on the Bureau staff 1925-1934. He joined the staff of Shell Oil Company in 1934 and was with that organization until his retirement in 1950. After his retirement he was a consultant to the Bureau of Economic Geology. ·-Adkins was widely recognized as the authority on the Mesozoic 9f Te~as. This was due to several significant publications and a general recognition of his great knowledge of the subject. "The Mesozoic Systems in Texas" (in University of Texas Bulletin 3232), "Handbook of Texas Cretaceous Fossils" (University of Texas Bulletin 2838 ), "Paleontological Correlation of the Fredericksburg and Washita Formations in North Texas" (with W. M. Win­ton, University of Texas Bulletin 1945), "Weno and Pawpaw Formations of the Texas Comanchean" (University of Texas Bulletin 1856) and "Geology and Mineral Resources of the Fort Stockton Quadrangle" (University of Texas Bulletin 2738) summarized or established much of the basic informa­tion on the Cretaceous of Texas. The importance of these publicati-­ = ~ 3~ ~ ~--: ~ aID = ~ ~ tD :~:: .. RIVER Thickness (feet) (c) Firm to plastic when wet or brittle when dry, olive-gray (5Y5/l dry, 5Y3/l wet), weathering to moderate yeJlowish-brown (10YR5/4 dry, 10YR4/4 wet), thinly to poorly bedded, richly fossiliferous, glau­conitic and carbonaceous shale, marly and lighter. colored in places.................... 1.5 (b) Large, hard, dense, moderate yellowish­brown (10YR5/4 dry, (10YR4/4 wet) on fresh break, pale yellowish-brown (10 YR6/2 dry) or dark yellowish-brown (10YR4/2 wet) on surface, rounded, much coalescing, nonfossiliferous, slight­ly argillaceous, calcareous concretions enclose very thin horizontal layers of marcasite; powdery-white (N9) calcite films on shrinkage cracks; form a nearly continuous narrow bench ........................ 0.5 Thickness (feet) Sparta formation, upper 2.0 feet exposed at low stage of river: (a) Loose, pale yellowish-brown ( 10YR6/2 dry) or dark yellowish-brown ( 10YR4/2 wet), massive, nonfossiliferous, musco­vitic, fine-grained sand; contains some firm, moderate yellowish-brown ( IOYR 6/4 dry, 10YR5/ 4 wet), weathering slightly darker, nonfossiliferous, slightly lignitic siltstone and partings of firm, pale yellowish-brown ( 10YR6/2 dry) or dark yellowish-brown (IOYR4/2 wet), wavy, laminated, lignitic shale; at least one 0.1-foot seam of black (Nl), mar­casitic, xyloid lignite; descends verti­cally into the river channel, bottom not exposed ........................................................ 2.0 PALEOECOLOGY AND SEDIMENTARY ENVIRONMENTS Two major lithotopes are indicated in the Stone City beds of the type locality by the two predominating sedimentary rocks which make up the Stone City beds: the glauconite marls or arenites and the brown or gray shales. The two differ not only in color, stratification, composition, and other physical features hut contrast also in the faunal remains they contain. Nearly all the pelecypod remains de­scribed below have been collected from the glauconite marls or arenites. They are richly fossiliferous throughout, whereas the dark nonglauconitic shales are so bar­ren that collecting molluscan fossils from them is a fruitless task. Some of the dark shales are somewhat glauconitic, and these usually contain a fauna limited to a few . species. There are several possible explanations for these differences in faunal remains and physical features. These possible expla­nations are discussed below. STRATIFICATION Bedding is strikingly different in the two rock types: the shales are laminated and fissile, except in the somewhat glau­conitic parts, but the glauconite marls and arenites lack for the most part well-devel­oped, traceable bedding planes or parting planes, although a crude sort of layering is indicated. How is it pos.sible that a glauconite marl bed about 5 feet thick can be laid down without stratification? Is it not physical}y impossible to deposit such a bed under water without producing simultaneously a multitude of re.cognizable bedding planes? Or is it po~ihle that during the gradual deposition of the sediment its bed­ding planes are continuously destroyed by certain agents or agencies which are in­dependent of the process responsible for the deposition of the sediment? That such agents or agencies were active during dep­osition is known because they have left recognizable traces. Many burrowing, digging, and plowing animals have left their remains in the glauconite beds, and in the foilowing par­agraphs some examples among the pelecy­pods are discu$ed. The species of the pelecypod family Pinnidae are well known for their ability to dig themselves in by squirting water out of the mantle cavity at the umbonal tip of the shell (fig. 5) . They are sedentary, living in quiet, protected waters buried in gravel, muddy grit, or sand in an upright attitude with the pointed umbonal tip of ----~-­ SURFACE OF SEDIMENT end only protrudes just above the surface, lvhile the enormous byssus reaches deep into the substratum, and its numerous threads are attached to pebbles, shells, and the like. However, the animal very rarely, if ever, changes its location (Winckworth, 1929; Grave, 1911). Although a member of the family Pinnidae has been found in the Stone City beds, the species is so rare that it can hardly have had much effect on the sediments (see Atrina cawcawensis (Harris) described below). The species of the pelecypod family Nuculidae (compare Nucula (Nucula) mauricensis Harris described below) , which is rather common in the Stone City glauconite beds, move by plowing through the sediment and in their normally buried position have the umbones pointing up­ward and protruding slightly above the surface of the sediment (Schenck, 1936, pp. 9-10; Quenstedt, 1930). The extinot genus Kymatox (see K. praelapUiosus Stenzel & Krause described below) , which is quite common at Stone City Bluff in the glauconite beds, must have lived burrowed in, because its valves are paper-thin, and the fossil shell is always preserved with the two valves locked shut. Kymatox is a member of the family Mac­ tridae, the members of which are nearly all burrowing. In some genera of this family the siphons are up to 3 times the length of the shell, allowing the animal to bury its shell to that depth in the sedi­ ment (Yonge, 1948). ,The pelecypod genus P holadomya (com­ pare Ph. petropolitana Stenzel & Twining described below) is adapted to life buried in and protected by the sediment with the gaping posterior end of the shell pointing obliquely upward. It too is always pre­ served with the two paper-thin valves locked shut. The habits and adaptations of Notocor­ bula gibba (Olivi) of the family Corbuli­ dae have recently been described by Yonge (1946). This living species is gregarious on muddy gravel or thick muddy sand with admixed gravel and small stones from below the Laminaria zone to depths of some 80 fathoms. Normally it is complete· ly buried with the long axis of the body in vertical attitude and the posterior end of the shell flush with or slightly below the surface of the sediment (fig. 6). The foot is extended and a single byssus thread attaches the animal to a suitable piece of gravel, stone, or shell in the sediment. ... z ct ...J ct :c .... x z L&.J ctz ..Jo Fie. 6. Notocorbula gibba (Olivi) in its natural attitude in the sediment, x7 natural size; modified from Yonge ( 1946, fig. 4). Anchored in this way the animal seems seldom to change position unless forcibly disturbed. If disturbed, it burrows down again with the aid of its extended foot. The animal is a sedentary suspension feed­er, that is, its food is the material suspend­ed in the water immediately above the sediment. Although Corhulas, being very small, penetrate only a little below the surface, they must have had great influ­ence on the transitory top layer of the sediment by reason of their gregarious habit and great numbers. ,Three species of Corbulidae are found in the Stone City beds, and all three are overly abundant; of the three species one is very similar to the species observed by Yonge ( 1946). The genus Abra is also lvell known for its ability to dig into the sediment. In less than a minute Abra alba (W. Wood) dis­appears below the surface of the sediment, whereas a Notocorbula gibba (Olivi) takes about 30 minutes to accomplish the same feat. Abra alba (W. Wood) is a de­posit feeder, that is, it feeds on the mate­rial accumulated on the surface of the sedi­ment; it does this through the inhalant siphon sucking in the surface deposits to­gether with the water. Because food in its vicinity is readily· depleted, the animal has to change its feeding area and dig in at a different location. For that reason it is able to dig in faster than N otocorbula gib­ba (Olivi), and its shell shape is better adapted to sliding into the sediment for it is a narrow, laterally compressed lens (Yonge, 1946, p. 363). The genus Abra has been found in the main glauconite, bed ( s) of the Stone City section. The shape and shell outline of the Stone City species are like those of the living Abra a/,ba (W. Wood). Among the family Tellinidae are many forms which are burrowing. Their adapta­ 4tions have been described and excellently analyzed by Yonge (1949). Tellina tenuis da Costa, for instance, burrows to a depth of up to 12 cm, although the adult animal is only about 1.6 cm long. When an animal is placed on sand the foot is soon extruded forward and downward and hooked re­peatedly under the sand until a grip is ob­tained. By contraction of. the foot the animal is then erected, and the shell glides diagonally down into the substratum through a succession of extrusions of the foot and jerks of the pedal muscle aided by some contractions of the adductor muscles. When completely buried, the ani­mal assumes a vertical attitude, and the siphons are pushed out to the surface. The whole process of burrowing, from the first extrusion of the foot to complete disap· pearance of the animal under the surface, can he completed within 30 seconds, be­cause the shell shape is very compressed, being about 5 times longer or 4 times higher than wide, and allows the animal to slide in rather easily. The siphons of Tellina are long and separate; the exhal­ant siphon is no longer than the shell, but the inhalant one can he extended up to four times the length of the shell. When the animal is feeding the inhalant siphon extends a little arched along the surface of the substratum, and the tip lies on or a little above the surface (fig. 7). Because INHALANT SIPHON SURFACE OF SEDlMENT Fie. 7. Tellina tenuis da Costa in its natural attitude in the sediment, x0.7 natural size. the siphon is rather narrow, the inhalant stream of water enters with comparatively high speed and is able to suck up organic material lying on or just above the sur­face, but not much sediment is drawn up. Tellina is buried deeply when the tide is out in order to avoid desiccation or sheets of fresh water spilling over the surface at low tide; the animal rises to normal po­sitions when the tide returns. Also as the food around its station is depleted, it has to move to another spot to begin afresh. Population densities of over 4000 living individuals per square meter have been reported for TeUtna tenuis da Costa, which is chiefly intertidal and extends only a few fathoms down. Such high population densities are apparently not unusual for smaller benthonic pelecypods. It is not necessary to enumerate other examples of burrowing, digging, or plow­ing pelecypods; many of them obviously do or did just that, and of these many are 1vell represented in the glauconite beds at Stone City. In general, pelecypods adapted to a life buried in sediment are stationary, for instance, Atrina. Hence they would have no effect on the sediment except in their immediate vicinity. However, there are others which can move about and do so on occasion or often, for instance, Tel­lina, Nucula, and Abra. In fact, plowing through sediment is probably the most common form of locomotion among the pelecypods. The depth to which the sedi­ment is plowed up or dug into is, of course, different for each species or for each ge­nus. In general it is true that the larger the pelecypod is, the deeper it can penetrate, either by burrowing or by plowing. Among those enumerated above Atrina cawcaw­ensis (Harris), Kymatox praelapidosus Stenzel &Krause, and Pholadomya petro­politana Stenzel &Twining were probably able to penetrate the deepest. An Atrina having a shell about 5 cm long must have been buried that deep approximately. Nev­ertheless, the other pelecypods capable of ogly shallow penetration, such as the Tel­linidae, Nuculidae, and Corhulidae, were very probably much more effective de­stroyers of stratification by reason of their very great abundance. Although they are not included in this investigation, the scaphopods and the deca­pod crustaceans, that is, the shrimps and crabs, must he mentioned here. Remains of a crab, Calappilia diglypta Stenzel (Stenzel, 1934) have been found in the main glauconite bed of the Stone City section. This crab, in common with all or nearly all groups related to it and belonging to the family Calappidae, has the eye sockets placed in such a fashion that they protrude above the level of the sediment when the animal buries itself shallowly in it. Although the genus Cal­appilia is extinct, it is safe to assume by reason of the position of its eye sockets that it buried itself just like its relatives do today. In addition to the pelecypods and crus­taceans there must have been present a host of other animals too soft-bodied to leave traces or remains. Among these may have been annelids, holothurians, and so forth, which live habitually buried at a deeper level than pelecypods and are better bur­rowers and for precisely that reason do not have need of any hard exoskeletons to protect them and the ref ore do not leave fossil remains. It may seem incongruous to claim that such animals were present if no traces of them can he demonstrated; and s~anding by itself that claim is in­deed incongruous. But if one can demon­strate that burrowing and digging pelecy­pods and crustaceans left their remains and were present in the sediment, it is self-evident that physical environmental conditions were favorable or at least not prohibitive for animals occupying the niche of burrowers and diggers. In other words, an abundance of remains of bur­rowing or digging pelecypods is indirect proof that other, soft-bodied burrowing or digging animals were present. The burrows themselves were general­ly not preserved as visible structures. Be­cause the material which filled them by sifting in from above was identical with the sediment into which the burrows were dug, it is now not possible to discern the burrow filling from the surrounding sed­iment. However, a few structures are pres­ent in the top of bed (s) which may be burrow fillings and which are composed of an indurated, glauconitic, fossiliferous, very impure, earthy clay-ironstone. Some of these structures are straight, others are corkscrew-shaped, vertical, and slightly flattened by early, almost syngenetic com­paction of the enclosing sediment as well as of the burrow filling (fig. 8) . They are similar to the corkscrew-shaped bodies ·from marine beds described by Mansfield ·Fie. s·. Spiral burrow filled with impure glau· conitic fossiliferous clay-ironstone from the top part of the main glauconite-marl bed (bed s) of the Stone City beds at Stone City Bluff, Texas; x0.75 natural size. (1927, 1930) and named by him Xeno­helix. While Mansfield regarded these structures as remains of some organism, likely of some marine plant, we consider them burrow fillings. .These structures have certain features which are indicative of their origin. However, description of these is certainly beyond the scope of the present paper. There is another feature of the glauco­nite beds which demonstrates the destruc­tion · of the stratification. Every grain of glauconite has an oval pellet shape, its surface is glossy as if rubbed smooth and polished, and compound grains are smoothed out to a single over-all pellet shape as if the roundish and originally separate component grains had been squeezed together and then their common outside surface rubbed smooth and pol­ished particularly well on the more ex­posed protruding convexities of the com­pound grain. The grains are very similar to the so-called mud grains described by Takahashi & Yagi (1929). Such shapes and f ea tu res are the result of ingestion by sediment-feeding animals. Every grain must have gone at least once through the intestinal tract of some animal, and many grains may have gone through more than once. In this connection observations given by Yonge ( 1949, p. 35) are significant. Abra alba (W. Wood) expels oval faecal pellets at frequent intervals, and these accumulate in piles around the cavity oc­cupied by the exhalant siphon, through which they were expelled. Abra is a de­posit-feeding bivalve which has a long, flexible inhalant siphon. The animal dis­plays quite extraordinary activity by bend­ing and twisting the narrow inhalant si­phon in all directions, while the tip inde­pendently makes smaller encircling move­ments and is never passive. The siphon of­ten arches over, and its intake opening searches the surface of the sediment, from which it actively pulls in organic debris and sediment particles. Pseudo£ aeces, that is, excess accumulations of larger sediment particles taken in and agglutinated by mu­cus, are suddenly expelled through the in­halant siphon every 2% minutes in a rapid stream for some three seconds. Sim­ilar pseudofaeces are expelled by the Telli­nas. However, the real faecal pellets are expelled through the other siphon. As to faecal pellets in the Clyde Sea, Moore (193la, p. 359) remarks: "In these muds up to 40 per cent of the fine mate­rial is often consolidated into faecal mass­es, and in extreme cases even the ·whole of the mud may he in the form of pellets." Most of the mud-dwelling species make pellets, which are surprisingly solid and resistant and can stand fairly rough han­dling. Each species produces one charac­teristic kind of pellet. The pellets of Abra a/,ba (W. Wood) described by Moore (193la, 193lb) are extremely uniform in shape, parallel-sided with rounded ends and circular cross section; their surface is smooth and regular, they are 0.25 to 0.3 mm in diameter and about 0.53 to 0.44 mm long; that is, they are strikingly simi­lar to the glauconite grains of the Stone City beds. Faecal pellets from maldanid polychaete annelid worms are also quite similar to the glauconite grains; the pel­lets from maldanid worms were found at one station to reach the approximate nwn­ber of 3,400 pellets per cubic centimeter and outnumbered all the others in the ratio of 100 to 1. In summary, stratification of the glau­conite beds was destroyed, as fast as the sediment was being laid down, through various animal activities, such as burrow­ing, digging, plowing, and sediment-feed­ing. The pace of destruction must have been equal to the rate of deposition and may even have exceeded it, that is, some parts may have been plowed up or in­gested repeatedly before they were finally placed out of reach of the animals by be­ing buried. Conversely, the rate of deposi­tion of the glauconite beds cannot have been very high at any one protracted length of time, for the moment when the rate of deposition exceeded the pace of destruction well-formed stratification planes would have been formed. It is of course well known that the rate of deposi­tion of glauconite beds is slow or at least moderate. The dark, carbonaceous or lignitic, lami­nated shales contrast with the glauconite beds as regards stratification. Their ex­cellent stratification is undisturbed by burrows or other traces of bottom-dwell­ing animals, and fossil remains of the lat­ter are lacking. In other words, bottom­dwelling animals either were unable to live on or in this sort of substratum or were so sparse that they did not affect the substratum sufficiently. SALINITY The glauconite beds contain a fairly rich fauna in which groups are well represented which can live only in sea water of normal salinity. Fairly common are remains of squids ( Belosepi,a), scaphopods ( Den,ta/,i­um and Cadul.us), bryozoa, and hexacor­als; echinoids, however, are very rare. The corals are represented by the genera Bafu­nophyUia and Turbinolia, both fairly common; EnJopachys, somewhat less com­mon; and Flabellum, Madracis, and Ocu­lina, somewhat rare. Individual remains of all these groups are of normal size and proportions except those of the compound corals Madracis and Oculina. The coral Madraci& normally is reef-forming, but the rare small colonies found in the Stone City beds are merely thin branches as are those of Oculina, having grown under unfavor­able marginal conditions. These sedentary animals, excepting the two compound cor­als, were evidently able to propagate, grow, and reach maturity normally with­out ever encountering conditions sufficient­ly adverse to kill them off or even to stunt their growth. This would mean, among other favorable conditions, that at the places where these corals grew normal salinity was maintained throughout their growth or, if salinity at these places ever sank below normal, it could not have re­mained below normal for very long nor could it have fallen very low. Minor tidal changes of salinity of this sort may have occurred at the places where the corals lived. Remains of the more mobile animals listed above, the squids, scaphopods, and echinoids, prove salinities only to the ex­tent that at least temporarily, if not per­manently, salinities were sufficiently near normal to allow these animals to migrate in from more favorable regions. The pres­ence of remains of these animals would not exclude fairly large seasonal or minor tidal fluctuations of salinity. Possibly the sedentary animal remains discussed above arc not quite uniformly distributed in the glauconite beds, thereby po$ibly indicat­ing some ftuctuations of salmity. However, this point was not investigated at the bluff. At any rate, the presence in the glauco­nite beds of remains of animals which can live only in sea water of normal salinity is a proof of salinity only insofar as at least temporarily and in some restricted locations salinities were normal. By contrast, practically no conclusion can be ·drawn about the salinity of the waters in which the dark shales were de­posited. The shales are very poor or lack­ing in remains of all significant groups of animals, be these animals restricted either to fresh or to brackish or to normal sea waters; hence the shales must have been deposited under peculiar conditions that inhibited nearly all animals from enter­ing or living in the area of shale deposi­tion. AERATION The factor of proper aeration of the waters above the sediments is of the great­est importance to the understanding of the distribution of animal remains in the Stone City beds. In this respect the difference be­tween the shales and the glauconite beds is again very large. If it is conceded that the glauconite beds were laid down under conditions fav­orable to a great many benthonic animals which were digging, burrow~ng, or plow­ing in or through the sediment, then it is also conceded that the water immediately above the sediment was well aerated most of the time, because all these animals de­rived the oxygen they breathed either from the water immediately above the surface of the sediment or from the water entering their burrows. Significant too is the fact that carbonaceous or lignitic mat­ter is practically absent from these glau­conite beds, although the dark shales above and below them contain very abun­dant carbonaceous or lignitic materials, finely divided or in larger pieces. During the time the Stone City· beds were depos­ited the supply of fragmented plant re­mains was abundant, and the areas in which glauconite beds were being depos­ited must have received their full share too. Probably deposition of the glauco­nite beds took place not only under well­aerated waters hut also at a rate slow enough to allow the admixed and mostly finely divided plant material to .be re­ moved either through oxidation or through digestion by bottom-feeding animals. The dark shales are rich in commi­nuted plant remains and in finely divided marcasite or marcasite concretions. :rhey were deposited under anaerobic conditions, and sulfate-reducing bacteria were pres-. ent. Their action reduced the sulfur en­tering the area of deposition as a soluble sulfate to produce H2S and free sulfur globules, which were stored in the bodies of the bacteria. Later the H2S or the free sulfur readily combined with iron whic~ originally had entered the area of depo­sition as a soluble sulfate or as the sol­uble Fe(C03 ) ·H2CQ3 to form iron sulfides. According to Emery & Rittenherg ( 1952, p. 791) "Little is known of the exact man­ner of formation of sedimentary iron sul­phides hut some workers bel:eve that the sequence is from hydrotroilite (FeS nH20) to melnikovite (a cryptocrystalline FeS2 ) to pyrite {cubic FeS2 ) in neutral or alka­line environments, or marcasite ( rhom­bic FeS2 ) in acid environments." Subse­quent rearrangement of the iron sulfide \\Tould result in the growth of marcasite concretions. For these reasons the surface and in­terior of the sediment, during deposition of the dark shales, was toxic to all the larger animals, and only a few stray re­mains are to he expected in the ·dark shales. The water above this sediment had some H2S in solution and may have been brackish. DEPTH Features of the bedding planes which indicate exposure to air, as for instarice, mud cracks and raindrop imprints, are comple~ely absent from the sedimentary rocks of the Stone City section, al­though the composition of most of the sed­iments would favor the making and re­tention of such features if conditions had been right. From these facts it is conclud­ed that the Stone City sediments were laid down beneath water and were never ex· po3ed to the air at Iow tide. If the sedi­ments were deposited in lagoons or es­tuaries,. the depth of deposition was suffi­ciently large to protect the sediments from expo3ure during low tide. The upper limit of dep~h there£ore was about low tide level or lower. The remains of corals in the glauconite beds probably are mo3t reliable indica­tors of the depth of deposition of these beds. The following depth ranges are giv­en by Vaughan & Wells (1943): Ba/,an­op.'iyllia, 0 to 600 fathoms; Endopachys, 20 to 330; Flabellum, 2 to 1,742 fathoms; Madracis, reefs to 350; and Oculina, 0 to 50 fathoms; Turbinolia s.s. is extinct. Among these Balanophyllia supplies the most weighty evidence, because it is the most common hexacoral of the S:one City beds. Althoug~1 the evidence does not lead to a very narrowly definable depth, shal­low depth and a limit of less than about 350 fathoms is indicated by the coral3. Depth ranges of pelecypod genera are probably in most cases not so me=in:ngful because all the species of the Stone City beds are extinct. However, some living species are so similar to those from the S:on3 City beds in size, shape, and other shell features that it is likely they occupy the same niche as their extinct relations did. The living species N otocorbula gi,bba (Olivi) is reported from below the Lami­naria zone to depths of some 80 fathoms (Yonge, 1946, p. 358) . The fossil species l\'otocorbula texana (Gabb) of the Stone City beds is very similar to the living species as far as one can tell from the shell ; it is also over 1y abundant and re­stricted to the Stone City beds. For these reasons much weight is attached to the ev· idence it furnishes. The two living species Abra nitida (Muller) and A. prismatica (Montagu) are reported by Spooner & Moore (1940, pp. 322-323) in small numbers near low water only at the seaward end of the Tam­ar estuary in southern England. The first species occurs along the edge of the West Muds and follows the main St. Johns chan­nel. The other species appears restricted to the edges of the tributary channel, at the mouth of which it mixes with other species. Both species are essentially ma· rine but evidently are able to tolerate a lowering of salinity; they are intolerant of intertidal exposure and live on soft, unstable mud of the tidal channel slopes. Anomia is a common shallow-water in­ h!lbitant, ranging from below low tide level to about 33 fathoms. Detached up· per valves are found in great numbers on tidal -flats and beaches exposed at low tide. Most of the valves of Anom"ia in the S~one City beds are detached upper valves and somewhat worn from having been shifted about. However, several shells were found which had the two valves in natural position. Anomia is very abundant in the glauconite beds. In short, Anomia is not easily interpreted in this connection, the great abundance of detached upper valves in the glauconite beds may pos­ sibly point to deposition above low tide level, but it may equally well mean that Anomias once they are dead fall apart very easily and that the lower valve is de­ stroyed more easily than the other one. At any rate, very shallow water is indicated, although the upper limit cannot be estab· lished by this evidence. The lower limit is very probably about 33 fathoms. Altogether, what evidence there is indi­ cates that the Stone City glauconite sedi­ ments were originally deposited at depths limited by low tide level at the highest at depths differing from those at which and by about 33 fathoms at the lowest. the glauconite beds were depositetl is not Whether the dark shales were deposited provable by the evidence available. WAVE AND CURRENT ACTION Water in motion has left well-recogniza­ble traces in some of the rocks of the Stone City beds. In this respect the dark shales differ again considerably from the glau­conite beds. In the glauconite beds are many layers that show the effects of working over by waves or tidal currents. A layer at the top of the main glauconite (bed (s) of the section described) is composed of mollus­can shell fragments and abundant shark teeth and fish earbones, all more or less well rounded and abraded through wear. The bony materials from which shark teeth and fish earbones are made are the hardest and most abrasion-resistant of the skeletal remains normally available in marine sediments of this sort, where usu­ally molluscan shell remains far outnum­ber skeletal remains. Their rounding, abra­sion, and relative concentration at this level is a sure sign of protracted wear and long-continued breakdown of an av­erage assembly of remains so that only the most resistant parts survived and be­came concentrated. The top layer of the main glauconite bed probably was affected by the action of waves or tidal currents more than any other layer of the Stone City beds. Elsewhere in the glauconite beds at Stone City Bluff are ill-defined lenticular layers composed of comminuted a~d abraded molluscan shells,. and many of the fossils scattered through these beds have rounded edges, worn sculpture, and abraded projections. Nearly all the valves of Anomia, a rather fragile, thin, and very light shell, are well worn at their edges, and some of the rare pelecypod species have not yet been found except as worn shells, for instance, V enericardia (Cla:i­bornicardia) trapaquara Harri~ and Dip­lodonta (Diplodonta) petropolitana Sten­zel (Pl. 14, figs. 6 to 11, and Pl. 9, figs. 3, 4). The presence of abraded shells in . near­!y all levels of the glauconite beds is a clear indication of shallow-water deposi­tion accompanied by the action of waves or tidal currents. The dark shales with their undisturbed and very fine bedding seem unaffected by water in motion; but there are many stringers of lenticular-bedded silts among them. The shale and silt beds probably represent deposition in areas not affected or only slightly affected by water in mo­tion. Certainly their deposition was not as much subject to these actions as was that of the glauconite beds. OYSTER REEFS The striking fact is that oyster beds have not been found in the Stone City beds from the Sabine River in the east to Atascosa County in the west, although everywhere along the outcrop the beds are clearly shallow-water deposits laid down in brackish to normal saline environ­ments. This lack cannot be blamed on the absence of species of oysters large enough and capable of forming typical oyster reefs. The Crassostrea frionis (Har­ris) is sufficiently large and heavy and belongs to that genus of oysters which has given rise to numerous species that are reef-forming. The species is not common at Stone City Bluff, but it cannot be termed rare for some minor fragments of the shell, usually abraded, can be collected there in many of the thicker glauconite beds. A few nearly complete valves have also been collected. But all these are abrad­ed, their frilled growth squamae are worn off, and attachment plugs of Anomias or young oysters or hryozoan colonies are grown on them on both the outside and the inside. Clearly these oyster valves have suffered from the effects of water in motion and are no longer in the place where they grew, having been transported to their present resting place as dead shells (Pl. 12, figs. 3-6, 8, 9) . Perhaps the absence of oyster reefs is best explained by the assumption that con­ ditions during the deposition of the Stone City beds were not f avorahle to their growth, because the submerged mud flats which gave rise to the dark shales of the Stone City beds had toxic surf aces too rich in H2S and the areas which produced the glauconite beds were covered by water too deep and too nearly normal in salinity to allow many oysters to grow. SYNTHESIS These observations and conclusions are too scanty to support a synthesis of the whole frame of _sedimentation during Stone City time. A good deal of the final synthesis must depend on regional strati­graphic data and conclusions. However, to evolve these here would lead too far away from the study of the pelecypods. The pre­liminary synthesis proffered below is to be judged in that light. The Stone City beds of the type locality were probably deposited in a lagoon or an estuary, chiefly near the seaward end of this body of water, where the salinity was nearly normal at times. The glauconite-rich beds may have been deposited in front of some weakly developed barrier islands in the shallow open sea. Wherever and when­ever salinity was nearly normal, the areas subject to waves or tidal currents were well aerated and could retain only a scant supply of sediment because of the effect of the water in motion; thereby the formation of glauconite was made pos­sible, and many benthonic animals were able to occupy the areas. These animals destroyed the stratification of the material as it was laid down, producing nearly uni­form structureless beds of glauconite marl or arenite enclosing many rolled and worn shells. These areas were essentially broad tidal channels or shallow shelf surf aces. Outside of the areas subject to the ac­tion of waves and tidal currents large submerged mud flats evolved, which were supplied with abundant plant debris and to which muddy rivers brought an ample sup­ply of sediment. Because of the lack of strong waves or tidal currents over these mud flats and the abundance of decaying plant remains, the mud flats evolved into toxic surfaces largely incapable of sup­porting benthonic animals. Fluctuation and shifting of the tidal channels resulted in an alternating depo­sition of dark shales and glauconite beds. Table I. Oligocene and Miocene stratigraphic units. UPPER z ~ ~ l) MIDDLE 0 ~­ LOWER UPPER z ~ ~ l) MIDDLE 0 0 ..... ~ 0 LOWER GATUN FORMATION of Panama BOWDEN FORMATION of Jamaica GURABO FORMATION of Dominican Republic CHIPOLA FORMATION of Florida At ::> .... z 0 0.. m 0.. "". 0 ..... ~ e .... ~ < ~ 0 Ul m :n .0 •rol CZ < 0 m Ul >4 ~ ..... Ul ix; iQ ~ •rol 0 ::> < ~ µ,. ~ '+-4 U) 0 re ~ s:: l) RS ...... Bucatunna clay Byram marl Glendon limestone MARIANNA FORMATION > RED .BLUFF CLAY ~ ~ ~ ~ ti1 0.. 0 0 u EUROPEAN STAGES PONTIAN SARMATIAN TORTONIAN . HELVETIAN BURDIGALIAN AQUITANIAN CHATTIAN RUPELIAN LATTORFIAN NoTE: Only the units mentioned in the text are included. Formations are printed in capital letters; members and le$er units are printed in both capital and lower-case letters. SOUTH VIRGIN!A ~ :::> AND AND EUROPEAN TEXAS LOUISIANA MI.SS1SSIPPI ALABAMA 0 NORTH MARY­ ~ STAGES l'.> CAROLINA LAND z YAZOO YAZOO LUDIAN 0 • • en .. :.:: ----------­ ~ u MOODYS Scutella bed t.:i < ~ MOODYS BRANCH ---­ ~ BARTONlAN BRANCH Dellet ~ :::> COOK Wood­ ~ <~ 0 f-4 :::> 0 z f-4 • • • AUVERSIAN Landrum u :::> stock t.:i z w u 0 w ~ >­ ..:I 0 Cl l Cl w ~ l LUTETIAN Pota­ w CUISIAN z w paco u 0 w YPRESIAN ~ w ?.t 0 ...:I SPARNACIAN AQUIA SOLOMON CR EEK HALL SUMMIT NAHEOLA NAHEOLA THANETIAN ~ Matthews Landing :.t PORTERS CREEK Cl (or WILLS POINT) PORTERS CREEK PORTERS CREEK MONTIAN ~ ~--------c ? DANIAN KINCAID Tehuacana NOTE: Only the units mentioned in the text are included. Some omitted units are indicated by asterisks. Formations are printed in capital letters; members and other lesser units are printed in both capital and lower-case letters. Gaps produced by regional disconformities are indicated by verti· cal lining. PALEONTOLOGIC PROCEDURES Some of the procedures used in this report are in need of explanation, ampli­fication, or possibly even defense. The following remarks concern these proce­dures and are recounted at random. The stratigraphic units mentioned in the text are shown on two tables (tables 1 and 2). These tables are based on published in­formation and on unpublished work done by Stenzel; see pages 36 and 37. The major classification and the ar­ rangement of the Pelecypoda used here is that proposed by the Committee on Pele­ cypoda of the Treatise on Invertebrate Paleontology. This classification and ar­ rangement are shown in a list of 148 mim­ eographed pages entitled ''Preliminary classification of the genera of the Pele­ cypoda" prepared by Dr. H. E. Vokes, which is a prodigious and very useful \vork of compilation. The endings of the scientific terms for taxa above the rank of genus have been changed deliberately from their usual form to fit the system of uniform endings proposed by Stenzel ( 1950) . For instance, the usual form of one of the superf amilies has been Nuculacea; the same superfam­ily here is called Nuculicae. The advan­tages of these new endings are that the new endings are uniform for tax a of the same rank, easy to remember, logical, and simple. If adopted by the majority of systematists, the new endings should serve to save time that is better spent on real progress than on checking of minor points of nomenclature. A list of the names aflect­ed by these new endings and contained in ·the present report is given below. If need be, the new names are to be credited to Stenzel as of the present date. The scheme of uniform endings pro­posed by Stenzel ( 1950) , leaving out those for the tribes, supertribes, and suhtribes, is briefly as follows: . superorder -1ca l neuterorder -ida . r gendersuborder -1na J superfamily -icae l feminine family -~dae J gender subfamily -1nae In these endings, the letter c denotes supertaxa, d denotes the main taxa, and n the subtaxa. Much of the work done for this report is based on topotype material. A great many Eocene and Oligocene pelecypods collected at their respective type locali­ties are available to us. Anyone familiar with the procedures of comparative pale­ontology can readily see that specimens available from well-defined type localities and identified correctly serve to protect the investigator from many pitfalls and incidental errors. Not only are topotype specimens often much easier identified, because geographic variation of the same species does not enter in the identification problem in their case, but also one is gen­erally assured of obtaining material of the same stratigraphic position as the orig­inal type material so that one can be cer­tain not to confound the particular species with its ancestor or descendant species, which are by the nature of their close re­lationships quite similar to the original species. In fact, many insufficiently de­scribed or poorly illustrated species can be identified only if the type locality was fixed so precisely that it can be recovered, and material can be collected there. Of course many species were originally de­scribed years ago before modern strati­graphic detail of the strata enclosing the species had been obtained. How·ever the ' stratigraphic position of these species can nQw be determined if the type locality is well fixed geographically. Many such de­terminations of the respective stratigraphic positions had to be made in order to make the species described long ago useful to modern work. Many of these determina­tions we owe to the extensive stratigraphic 'vork done by many geologists from about 1925 on to today, chiefly by geologists employed by the oil companies. In view of the obvious necessity to pro­vide exact type locality data in the orig­inal description of a species one is struck by the manner with which such data were treated by some species describers, even by some outstanding paleontologists. What is one to think of the foil owing published unamplified data accompanying formal descriptions of new species? "Lo­cality.-Texas" (1865) or "Eocene of Conecuh County, Alabama'' (1903) or "Clarke County, Alabama" (1933). Are undescribed species so rare that one has to describe material which was collected carelessly and is insufficiently documented as to type locality? Lack of restraint in describing new species from undocument­ed material collected by someone else or lack of care in obtaining sufficient locality data from the collector are certainly not halhnarks of outstanding work. Therefore, it is rather surprising to see that succeed­ing investigators in general have accepted as valid such poorly documented material and have spent an inordinate amount of time in straightening out such ill-£ ounded species and their type localities and strati­graphic positions. We have followed this polite trend too and have used much time on work that by rights should have been furnished by the original author of the re­spective species. For this reason we believe we are entitled to voice our criticism even where outstanding paleontologists are in­volved. The following example from Texas will suffice to illustrate the havoc wrought by insufficient locality data. Gabb described as a new species ?M eretrix yoakumii "From a brown, highly ferruginous sand­stone, (Eocene), Caddo Peak, Texas. Col­lected by Prof. Yoakum'' (1861, p. 370) and Perna texana "From a coarse brown, ·highly fossiliferous Eocene sandstone from Caddo Peak, ;fexas'' (1861, p. 371) ob­tained from Dr. Francis Moore, who was the State Geologist of Texas from 1860 to 1861. Brown ferruginous sandstones are common in the Eocene rocks of Texas so that both new species are plausibly as­sociated with the right kind of matrix. Of course Gabb had ample opportunity to ask either one of his two friends by letter w·here Caddo Peak is located. He may have even known where it is but may not have taken the trouble to enlarge upon this scanty locality information. These two fossils were listed as Eocene by Conrad (1865a, pp. 5, 10; 1866, p. 7, no. 169; p. 5, no. 94) and Heilprin ( 1891, pp. 402, 403) . Harris ( 1895b, p. 46, pl. 1, fig. 2) claimed to have found a few and imperfect specimens of Modiola texana (Gabb) [= Perna texana Gabb] in the Eocene collections of the Geological Sur­vey of Texas, gave as the stratigraphic po­sition of the species "Lower Claiborne Eo­cene," and listed the following localities: "Caddo Peak, Texas, Gabb. Two miles southwest of Campbellton, Atascosa Co.; two miles east of Arnold's ranch, Frio Co., Tex. Near Red Land, La." The speci­men figured by Harris was from the Eo­cene of Red Land, Louisiana. Dall ( 1890/1903, p. 796) too listed this species as Tertiary and expanded its stratigraphic position to "Lower Claibornian and Mid­way Eocene." Later Harris (1919, pp. 32­33, pl. 17, figs. 6, 7) confidently ref erred several other Eocene specimens to this species and also discussed (1919, pp. 150­151) the other one of the two species, but declined to refer to it any specimens of his. Palmer (1927 /29, pp. 40-41 or 248­249) discussed ?Meretrix yoakumii Gahb, placed it in Pitari.a (Lamelliconcha) al­though the hinge of the only specimen was not exposed, and listed it as Eocene. Guided by this information Stenzel had searched the Texas Coastal Plain Tertiary outcrop area for at least 15 years for a Caddo Peak without ever finding any leads. Accidentally Caddo Peak was re­discovered, so-to-say, in October 1949. It is in northern Johnson County, near the old Caddo Post Office, on the old road from Cleburne to Fort Worth; it is a prom­inent hill and is still known locally under that name. The hill is made up of the same kind of sandstone as forms the ma­trix of the type specimens of Gabb's, which are still preserved at the Academy of Natural Sciences of Philadelphia. How­ever, the sandstone is in the Woodbine group, Cenomanian Cretaceous. Of course Cretaceous paleontologists had been entirely una,vare of Gabb's spe­cies because they had always been regard­ed as Eocene. In explanation of that situa­tion it must be remembered that the fer­ruginous and fossiliferous sandstone of the Woodbine group had been regarded as Tertiary in 1859 by Francis Moore, Jr. ( 1859, p. 97), one of the collectors of this material, and in 1858 to 1861 by the Shu­mard brothers (G. G. Shumard, 1886, pp. 127-131), who were at that time the State Geologists of Texas, presumably because they thought Cretaceous formations in this region had to be chalks, limestones, or marls, and Gahb had simply followed them. .The situation was brought to the attention of L. W. Stephenson, who has discussed one of the two species involved (1953, p. 85). However, as yet no attempt has been made to collect on Caddo Peak topotype specimens of the two species described by Gahh and to compare such topotype specimens with the original types in Philadelphia. Some difficulties were encountered in measuring the lengths of the pelecypod shells. Measurements may differ consid­erably depending on how length is de­fined. Some authors define the length of a shel I as its greatest dimension, no matter how much inclined this dimension is with · reference to the hinge axis. Others define the length as the greatest dimension ob­tained by projecting the ends of the shell onto the line of the hinge axis. The latter definition is pref erred because it is mor­phologically more significant than the for­mer. However, if this definition is to he followed it is nece~ary to locate correctly the hinge axis of the shell. While the axis can he determined very easily in shells which have a straight, linear hinge pattern, for example, Arca, it is rather difficult to· ascertain in those more numerous forms which have variously curved or otherwise complex hinge patterns. Even such com­paratively simple hinges as those of Nu­cula, for instance, which are strongly arched or in the form of an inverted V, present difficult interpretations. In these latter forms the position and attitude of the ligament is the determining fac~or. Ob­viously the hinge axis must he in harmony with the functioning part of the ligament, that is, the last-grown part of the ligament. Comparison with shells of related living species which have their valves joined by the ligament and in which the ligament is still present is found to be indispensable (compare fig. 10 on p. 77). ConverseIy the height of a sh el 1 is the greatest dimension obtained by projecting the umbonal region and the ventral mar­gin on~o a line at right angles to the hinge axis and within the plane of symmetry be­tween the two valves. In itself the height. is not as significant as is the height cal­culated in percent of the length. The lat­ter figure is given in many of the follow­ing descriptions. The width of a shell is its greatest transverse dimension. Generally the width of one valve is half the width of the whole shell, if the valves are equal. However, many forms have various inter­locking devices at the valve margins and some forms have overlapping valves; in their case the width of a single valve is slightly to considerably larger than half the width of the shell. When referring to the degree of infla­tion of a valve we have tried to use more precise terms than the usual ambiguous comparative words such as much, little, strongly, etc. Inflation has been measured and calculated as the width of a single valve given in terms of percent of its height, and these measurements are given in the descriptive text. Our terminology for inflation of a valve is as follows: weak­ly inflated is 10 percent or less, moderately inflated is 10 to 30 percent, strong I y in ­flated is 30 to 50 percent, and overinflated is above 50 percent of the height of the valve. When a complete shell, having both valves, is measured the combined width is generally twice the width of a single valve, and the definitions given above must be modified by doubling the percent figures; for example, 60 to 100 percent of the height of a shell is called strongly inflated in that case. The position of the umbo can be de­fined more precisely than by the use of the words median, anterior, or posterior, if one calculates its position as a fraction of the length of the shell. Using that system and expressing the fraction in decimals, 0.50 is exactly median position, figures smaller than 0.50 are all various anterior positions, and figures larger than 0.50 are all various posterior positions. Normally, this system is precise and consistent, but the resultant calculated figures vary great­ly if the position of the hinge axis is open to reinterpretation. Because the length of a shell is obtained by projecting onto the hinge axis, slight readjustments and rein­terpretations of the direction of the hinge axis result in large errors. These errors in turn affect the calculation of the position of theumbo. Most types and figured specimens are on deposit at the Bureau of Economic Geology of The University of Texas in Austin, Texas, U.S.A. However, some additional unfigured paratypes are now available at the University of Houston, Houston, Texas. We are fortunate in having been able to figure some of the types on deposit at the Academy of Natural Sciences of Phila­delphia, Pennsylvania. LIST OF NEW NAMES NEW UNIFORM ENDINGS OF SUPERFAMILIES Nuculicae Nuculanicae Arcicae Glycymeridicae Mytilicae Pinnicae Pteriicae Pectinicae Limicae Ostreicae Anomiicae Carditicae Lucinicae Tellinicae Mactricae Venericae Laternulicae Myicae Poromyicae NEW SUBFAMILY Kymatoxinae Stenzel & Krause NEW GENERA AND SUBGENERA Nanohalus Stenzel & Twining, n. gen. Claibomicardia Stenzel &Krause, n. subgen. Kymatox Stenzel & Krause, n. gen. Vokesula Stenzel & Twining, n. gen. NEW SPECIES AND SUBSPECIES N ucula ( N ucula) smithvillensis Stenzel & Twining Ca/,orhadia (Calorhadia) praecompsa Stenzel & Krause Ca/,orhadia ( Litorhadia) petro politana Stenzel & Krause Calorhadia ( Litorhadia?) evanescentior Stenzel &Krause Arca (Arca) petropolitana Stenzel &Krause Barbatia ( Barbatia) uxorispa/,meri Stenzel & Krause Glycymeris petropolitana Stenzel &Twining Pachecoa ( Pachecoa) smithvillensis Stenzel & Twining Pachecoa ( Pachecoa) catonis Stenzel & Twining Mauricia leonia Stenzel & Krause Pteria ( Pteria) petropolitana Stenzel &Twining Lima ( Limatulella) smithvillensis Stenzel & Twining Lima (Ctenoides) bastropensis Stenzel &Twining Cubitostn~a (Cub;tostrea) sanctiaugustini Stenzel & Twining Cubitostrea ( Cubitostrea) petro politana Stenzel &Twining Diplodonta (Diplodonta) petropolitana Stenzel Abra (Abra) petropolitana Stenzel Tellina (M oerella) petro politana Stenzel & Krause Kymatox praelapidosus Stenzel &Krause Katherinella smithvillensis Stenzel & Krause Katherinella trinitati.~ Stenzel &Krause KatherineUa? texitrina Stenzel &Krause Pitar (Ca/,pitaria) petropolitanus Stenzel & Krause Pitar (Cs Creek, Charles County, Maryland. Compare Clark & Martin ( 190lb, pp. 200-201. pl. 56, figs. 9-10). (8) C. costellata (G. B. Sowerby), living on the coast of Lower California to Panama. Com­pare Hertlein & Strong (1940, pp. 398-399, pl. 2, fig;. 10) . (9) C. marella (Hertlein, Hanna, & Strong), living in the gulf of Chiriqui, Panama. Compare Hertlein & Strong ( 1940, pp. 399--400, pl. 2, figs. 12, 13). The list is probably incomplete. How· ever, we exclude from Cal,orhadia s . . s. several species which have been included by other writers. There is very consider-. able doubt whether C.? mater (Meyer) be­longs here. The Stone City species C. compsa ( Gabb) differs from the other species list­ed above by the ·very strong development of the nodes at the first rostral ray. Among the other species, C. reginajacksonis (Har­ris), C. opulenta (Conrad), C.? mater (Meyer), and C. pharcida (Dall) have the nodes at the first rostral ray either not at all stronger or slightly stronger developed than the concentric sculpture of the disk. Although C. praecompsa Stenzel &Krause, n. sp., has well-developed nodes, they are weaker than those of C. compsa (Gabb). ,The other species are not available for . comparison. . Harris (in Harris &·Palmer, 1946, pp. 5~56) discussed this group of Calorhadias and called it the "opulenta stock.'' Hence his opulenta stock . is what we call Calor­haJ,ia s. s. Harris regarded Cal,orhaJ,ia as a section but included in it other species be­sides the opulenta stock. These other spe­cies we either exclude from Calorhadia s. s. or consider them dubious member . species. We do not follow Gardner (1945, pp. .45-46) in placing C. compsa (Gabb) in the subgenus CalorhaJ,ia ( Litorhadia}, be­cause the species has none of the charac­teristics of Litorhadia and is very close to the type species of Calorhadia s. s. Type data.-Gabb's type specimen is probably at the Academy of Natural Sciences of Philadelphia, Philadelphia, Pennsylvania; however, it was not found by Stenzel in 1948 and 1953. Type locality.-Stone City Bluff. Geologic horizon.-The species is re­stricted to the Stone City beds. For dis­tribution in the individual beds of the Stone City Bluff, see table 3. CALORHADIA (CALORBADIA) PRAECOMPSA Stenzel & Krause, n. sp. Pl. 1, figs. 15-17 Description.-Shell to about 18 mm long and elongate (height is 41 percent of length). Um.bones slightly anterior (at 0.40 of length). Anterior end rounded. Posterior end acuminate, obliquely trun­cate. Base rounded with the curvature in­creasing toward the anterior. Lunule smooth and bisected by an inconspicuous raised longitudinal line. Escutcheon smooth and bisected by a raised line. Concentric threads, 3.3 per mm, evenly spaced, very narrow, separated by inter­spaces which are 4 to 6 times wider than the threads, extend from the margin of the lunule to the escutcheon. On crossing the first rostral r~y the threads turn slightly and increase in size to form a radial row of narrow and transverse nodes. A radial groove delimits the first rostral ray on the rostral side, but the threads cross it; here the threads are finer. The threads cross the rostrum increasing in size grad­ually toward the margin of the escutcheon, where they turn sharply toward the umbo. A ray extending from umbo to antero-ven­tral margin is produced by the swelling and heightening of each concentric thread. Dimensions.-The holotype has the tip of the ro3trum missing and is 15.2 mm long (original length 16.0 mm estimated), 6.5 mm high, and 1. 7 mm wide . Remarks.-This species is rare and ap­parently restricted to the W eches forma­tion, Middle Eocene. ;fhe Stone City species C. (C.) comp· sa (Gabh) is very similar but has more ornamentation on the lunule and escutch­eon, much narrower interspaces between the concentric threads, and higher and wider transverse nodes on the first rostral ray. Type data.-Holotype and 2 f ragmen­tary paratypes, all left valves, are at the Bureau of Economic Geology, The Univer­sity of Texas, Austin, Texas. Type locality.-Bluff on right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. .Geologic horizon.-The type specimens are from the Viesca member of the Weches formation, Claiborne group, Middle Eo­cene. Subgenus LITORHADIA Stewart, 1930 Author.-Stewart, R. B. (1930) Gabh's California Cretaceous and Tertiary type lamellibranchs: Acad. Nat. Sci. Philadel­phia Spec. Pub. 3, pp. 52-53. [August 9] Type species.-" 'Leda' acala Dall (1890/1903, p. 586, pl. 32, fig. 3)='Yol­dia' aldrichiana Harris (1897, p. 245, pl. 14, fig.15-Wood's Bluff)"== Calorhadia ( Litorhadia) aldrichiana (Harris). Type designation.-Original, Stewart (1930, p. 52). First description of type species.-Har­ris, G. D. (1897), The Lignitic stage, pt. 1, Stratigraphy and Pelecypoda: Bull. Am. Paleontology, vol. 2, no. 9, pp. 245-246 of vol., pl. 8, fig. 15. Type locality and horizon of type spe­cies.-Wood's Bluff, on left bank of the Tombigbee River, south half of section 10, ,T. 11 N., R. 1 E., northwestern Clarke County, Alabama, near town of Wood­bluff. Bashi marl member of Hatchetigbee formation, Wilcox group, Lower Eocene. Subgeneric description.-Vmbones con­siderably anterior (at approximately 0.36 of length). Anterior end rounded, some­what produced. Posterior end produced, without any carinae. Base arcuate but with a tendency to rectilinear toward the rostrum. Outer surface has concentric raised threads, evanescent toward anterior and posterior; rostrum without threads. Range of subgenus.-The subgenus is apparently represented in the Paleocene; compare "Leda elongatoides var.?" (Har­ris, 1896a, p. 169 of vol., pl. 4, fig. 10) from the Matthews Landing marl mem­ber of the Porters Creek formation, Mid­way group. The type species of the sub­genus is from the Wilcox group, Lower Eocene, and the species C. (L.) petropoli­tana Stenzel &Krause, n. sp., is from the Claiborne group, Middle Eocene. Remarks.-Specimens of the type spe­cies were not available for study; hence there is considerable doubt concerning the description, range, and taxonomic limits of the subgenus. CALORHADIA (LITORHADIA) PETROPOLITANA Stenzel & Krause, n. ap. Pl. 4, figs. 18-20 Description.-Sheil small, to about 10 mm long, elongate (height is about 50 percent of length). Umbones somewhat anterior, at about 0.45 of length of valve. Anterior end sharply rounded. Posterior end nasute but not truncate. Base broadly arcuate medially, nearly rectilinear be­tween middle and rostrum. Lunule almost linear, bisected hy an obsolescent ridge. Escutcheon long, shallow, bisected by a rounded ridge. On the inner surface of the valve there is a well-defined short ridge at the ros­trum, parallel to the dorsal edge of the valve and terminating abruptly less than one millimeter from the tip of the ros­trum. Pallial sinus very faint, long, rounded. Seu I pture consists of f nir I y strong, reg­ular concentric threads, 7.0 per mm, rounded in cross section, separated by in­terspaces of same size; concentric threads absent in neanic part of shell, to about 0.6 mm from umbo; the threads disappear an­teriorly halfway between anterior extrem­ity and a vertical line through the apex; they disappear also posteriorly about one millimeter from the posterior extremity. Rostrum glistening, covered with sharply and simply curved growth lines. Dimen,sions.-The following type speci­mens were measured in millimeters: WIDTH BED VALVE LENGTH HEIGHT OF VALVE (j) Left 7.0 est. 3.5 1.0 (d) Right 7.3 est. 3.7 1.1 Right 5.0 2.5 0.9 Right 5.0 est. 2.7 0.9 (c) Right 9.0 est. 4.5 1.6 (figured para type) Right 7.5 3.9 1.5 Left 6.4 3.3 1.3 (holotype) Left 6.2 3.1 1.1 Right 5.0 est. 2.8 1.3 Average 6.5 3.3 1.2 Remarks.-Although it is believed that Calorhadia (Litorhadia) petropalitana Stenzel & Krause is correctly placed in the subgenus Litorhadia, some doubt remains because the type species of the subgenus has not been seen. This is the common small nuculanid from the Stone City beds. The common small nuculanid in the Cook Mountain formation of the same area is "Leda'· houstonia Harris (Harris, 1895b, p. 47, pl. 1, fig. 5) originally described from the Hurricane lentil at the base of the Lan­drum member of the Cook Mountain for­mation of Alabama Ferry on the Trinity River, Houston County, Texas (see Sten­zel, 1940c); Bur. Econ. Geology locality no. 113-T-9. The latter is easily distin­guished, among other features, by its raised radial threads on the rostrum and the very narrow interspaces between the flat-topped concentric threads, which give an appearance of imp~lines. It is ap­parent that "Leda'' houstonia Harris is not a member of the subgenus Litorhadia. Type data.-There are a holotype and 15 paratypes altogether deposited at the Bureau of Economic Geology, The Univer­sity of Texas, Austin, Texas. Ty-pe locality.-Stone City Bluff. Geologic korizon.-The species is re­stricted to the Stone City beds. For dis­tribution in the individual beds of the Stone City Bluff, see table 3. CALORBADIA (UTORBADIA ?) BASTROPENSIS (Barri•) Pl. 4, figs. 10, 11 1895 Leda bastropensis HARRIS, G. D., New and otherwise interesting Tertiary Mollusca from Texas: Acad. Nat. Sci. Philadelphia Proc. 1895, pp. 46--47, pl. 1, fig. 3. [April 9] 1919 Leda bastropensis HARRIS, G. D., Pelecy­poda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, no. 31, p. 64, pl. 24, figs. 9, 10. 1923 ?Not Leda bastropensis Harris. TRow­BRIDGE, A. C., A geologic reconnaissance in the Gulf Coastal Plain of Texas near the Rio Grande: U.S. Geol. Survey Prof. Paper 131-D, pp. 95, 96. 1931 Not Leda bastropensis Harris. RENICK, B. C., & STENZEL, H. B., The lower Clai­borne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. 1945 ?Not Calorluzdia (Litorhadia) bastropensis (Harris). GARDNF.R, JuuA, Mollusca of the Tertiary formations of northeastern Mex­ico: Geol. Soc. America Mem. 11, p. 46. · Origi,nal. description.-General form as fig­ured; medial portions of the valves with regular, strong, concentric striae; striae obsolete on the anterior end and on the post-um.bonal slope the latter with a shallow furrow extending fro~ the umbo to near the extremity of the valve; within the valve, a raised line or ridge, emanating from the umhonal region and extending along be­neath the hinge finally terminates in the middle of the posterior end and is there slightly en­larged. This species differs from L. plicata Lea in its lack of striation over portions of the exterior, and the more central positions of the u.mbones. From L. mater Mr., bastropensis is distinguished by its want of anterior radiating sulci, its lack of post-umbonal striation, and by its form. This is readily distinguished from L. albirupina Har. since it lacks the smooth Yoldia-like aspect about the umbones so characteristic of that species. [Harris, 1895b, pp. 46-47.] Revis-ed description (based on holo­type) .-Shell originally 11.0 mm long, elongate (height is 40 percent of length). Umhones somewhat anterior, at 0.40 of length of valve. Outline of dorsal margin from umbo to tip of rostrum is concavely curved; this feature is notably different in the type species of Litorhadia. Rostrum smooth, convex in cross section. Rostral ray broadly' rounded in cross section; a shallow radial groove parallels the rostral ray on the dorsal side. Lunule not well de­fined. Escutcheon smooth and bisected by a raised line. On the inner surf ace of the valve there is a well-defined ridge at the rostrum, curved parallel with the dorsal edge of the valve, increasing in size in distal direc­tion. Sculpture consists of evenly spaced con­centric threads, 3.8 per mm, narrower than their interspaces, rounded on top, eva­nescent near anterior extremity, stopping just short of the rostral ray posteriorly. Rostral ray smooth. Dimensions.-Holotype, a right valve, has the posterior tip missing and is 10.3 mm long (original length 11.0 mm esti­mated), 4.4 mm high, and 1.5 mm wide. Remarks.-ln order to correct several misconceptions, Ca/,orhadia ( Litorhadia) bastropensis (Harris) is discussed here .. Harris (1895b, p. 47) with the original description of the species gave only two localities, neither of which is near Bas­trop or in Bastrop County: "Rio Grande at Starr-Zapata Co. line" and "Brazos River, one mile below Milam-Burleson Co. line, Tex." He later (Harris, 1919, p. 64, pl. 24, figs. 9, 10) repeated the same lo­caJities and added "Ft. Gaines, Ga.?" in the text and "Sabine River" in the expla­nation of one of the two figures. Neither of these additional localities is near Bas:rop or in Bastrop County. In both publications he figured the type; however, the earlier figure is a line drawing and not clearly identifiable. Gardner ( 1945, p. 46) stated that the type was probably lost and that the trivial name was probably a misnomer because the form figured by Harris in 1919 came from the Rio Grande emhayment. The holotype at Austin hears a red mark, such as is on nearly all Harris' type spe­cimens deposited here, and is undoubtedly the shell figured by Harris (1919, pl. 24, fig. 9) . With the type specimen is the orig­inal label, probably in Harris' handwrit­ing: "221 / Leda bastropensis / Harris / Sta 12. Smithville / Bastrop Co. Tex''. The Station 12 is indeed "Smithville'' ac­cording to the old Texas Geological Sur­vey numbering system and is in Bastrop County~ In addition, the old card index file of the Texas Geological Survey has a card "12 Smithville / . . . Leda hastrop­ens1s. I ..." The Smithville Blufl from which Har­ris collected his material exposes the Vies­ca member of the Weches formation, Clai­borne group, Middle Eocene. However, no additional material of this species has been found there in spite of extensive collect­ing. The related species C. (L.?) evanes­centior Stenzel & Krause, n. sp., from the Stone City beds, is very similar to C. (L.?) bastropensis (Harris) and was confused with it by Renick &Stenzel (1931, p. 104). We question the reference to C. (L.?) bas­tropensis (Harris) of Cook Mountain forms from the Rio Grande emhayment by Gardner (in ,Trowbridge, 1923, pp. 95, 96; Gardner, 1945, p. 46). The species is rare and apparently re­str.icted to the W eches formation. It is larger and has coarser sculpture than C. (L.?) evanescentior Stenzel & Krause from the Stone City beds. The other close­ly related species, C. (L.?) albirupina (Harris), from the Jackson group at White Bluff, Jefferson County, Arkansas, has a shorter anterior end and a straight pos­tero-ventral margin. Type data.-Holotype, a right valve, no. 221, Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Bluff on right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. Geologic horizon.-The holotype is from the Viesca member of the Weches formation, Claiborne group, Middle Eo· cene. CALORHADIA (LITORHADIA?) EVANESCENTIOR Stenzel & Krause, n. sp. Pl. 4, ti.gs. 21-25 Description.-Shell small, to about 9 mm long, elongate (height is about 35 per­cent of length). Umbones median, at about 0.50 of length of valve, inconspicu­ous. Anterior end sharply rounded, pro­duced. Posterior end nasute and slightly upturned. Outline of dorsal margin from umbo to tip of rostrum is concavely curved; this feature is notably different in the type species of Litorhadia. Base broad­ly arcuate. Lunule not well defined. Es­cutcheon long, shallow, smooth, bisected by a low rounded ridge. On the inner surface of the valve there is a well-defined ridge at the rostrum, parallel to the dorsal edge of the valve and terminating in a node near the tip of the rostrum. Sculpture consists of weak, regular, concentric threads, about 11 per millime­ter, flattened on top, separated by narrow­er interspaces, absent in neanic part of shell to about 1.5 mm from umho; the threads disappear anteriorly halfway be­tween anterior extremity and a vertical line through the umho; they disappear also posteriorly before the radial rostral ray is reached. Rostral ray smooth, very low, broadly rounded in cross section· a . ' very shallow radial groove parallels the rostral ray on its dorsal side. Rostrum smooth, glistening, convex in cross sec­tion, covered with sharply and simply curved growth lines. Dimensions.-The following type speci­mens were. measured in mil1ime~ers: WIDTH BED VALVE LENGTH HEIGHT OF VALVE (s) Right 8.2 3.2 I.I Right 7.8 3.1 0.9 (holotype) Left 7.3 est. 2.8 0.8 Right 5.8 2.2 0.7 Right 5.2 2.1 0.6 Average 6.9 2.7 0.8 Remarks.-The fragile Calorhadia (Lit­orhadia?) evanescentior is rare and ap· parently restricted to the Stone City beds. It has been found in beds ( u), (s), and ( d) of the Stone City Bluff. It is similar to C. (L.?) bastropensis (Harris) of the Weches formation but is sma~ler and smoother; the concentric threads evanesce at a slightly greater dis­tance from the rostral ray and also at a very much greater distance from the an­terior extremity; the threads are lower, wider, more crowded, and have narrower interspaces. The rostral ray and parallel groove of C. (L.?} evanescentior Stenzel & Krause, n. sp., are less pronounced. The two species are very closely related. Type data.-There are a holotype and 6 paratypes deposited at the Bureau of Economic Geology, The University of Tex­ as, Austin, Texas. Type locality.-Stone City Bluff. Geologic horizon.-Beds (s) , ( u) , and (d) of the Stone City beds, Claiborne group, Middle Eocene. Genas ORTHOYOLDIA Verrill & Bush, 1897 Author.-Verrill, A. E., &Bush, K. J. (1897) Revision of the genera of Ledidae and Nuculidae of the Atlantic Coast of the United States: Am. Jour. Sci., 4th ser., vol. 3, p. 55. Type species.-"Orthoyoldia scapina (Dall)" = Orthoyoldia scapania (Dall). The trivial name is misprinted in Verrill &Bush. Type designation.-Original, Verrill & Bush (1897, p. 55). First description of type species.-Dall, W. H. (1890) Preliminary report on the collection of Mollusca and Brachiopoda obtained in 1887-'88: U. S. Nat. Mus. Proc., vol. 12, no. 773, pp. 254-255, pl. 13, fig. 6. Type locality and horizon of type spe­ cies.-East of Rio de Janeiro, Brazil, at 59 fathoms, on mud; living. Generic description.-Shell thin, por­cellaneous, small, to about 25 mm long, oblong-ovate, moderately to strongly in­flated. Um.bones inconspicuous, hardly raised above hinge line; position of um­hones anterior to somewhat anterior, at 0.35 to 0.43 of length of valve. Both ends blunt or rounded, the posterior end slightly narrower in . some species. No rostrum or carina present. Lunule and escutcheon very narrow. Ligament pit relatively small, wide, tri­angular. Hinge consists of two series· of small chevron-shaped teeth, the posterior s~ries longer than the anterior. Pallial sinus deep, wide, broadly U-shaped. Outer surface smooth or obscurely and concentrical1y striate. Range of genus.-The genus is well .represented from the Middle Eocene to the present. The following species have been placed in this genus by various authors: ( 1) 0. scapania (Dall) living off the coast of Brazil. (2) 0. solenoides (Dall) living in the Gulf of Mexico, at 118 fathoms. ( 3) 0. serica (Conrad) from the Vicksburg group, Oligocene, of Mississippi. (4) 0. ovaUs (Gabb) from the Gurabo for­mation of the Dominican Republic and the Bowden formation uf Jamaica, Middle Mtocene. (5) 0. bocasensis (Olsson) from the Miocene of Bocas del Toro Island, Panama. (6) 0. rubamni.s tHarris) from the Jackson group, Upper Eocene, of Arkansas. (7) 0. psammotaea Dall from the Claiborne. group, Middle Eocene, of the Gulf Coastal Plain. (8) 0. claibornensis (Conrad), a dubious spe­cies; see Remarks under 0. psammotaea Dall. Remarks.-Woodring (1925, pp. 21, 22) has noted the morphological and eco­logical differences between Orthoyoldia and Yoldia s. s. The latter is boreal and slightly rostrate, has stronger sculpture, two subequal series of teeth, and a large wide resilifer, which extends far below the teeth. Orthoyoldia is characteristic of trop­ical and subtropical seas. ORTHOYOLDIA PSAMMOTAEA Dall Pl. 4, figs. 26--30 1898 Y oldia (section Orthoyoldia) psammotaea DALL, W. H., Contributions to the Tertiary fauna of Florida, etc.: Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 596, pl. 34, fig. 20. [October 15] 1919 Y oldia psammotaea Dall (part) . HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, no. 31, pp. 72-73, pl. 25, figs. 25, 27, 29, not 26, 28, 30, 31. 1931 Yoldia psammotaea Dall. RENICK, B. C., &STENZEL, H. B., The LoweF Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. 1932 ? Y oldia cf. Y. psammotea D·all. TROW· BRIDGE, A. C., Tertiary and Quaternary geology of the lower Rio Grande region, Texas: U. S. Geol. Survey Bull. 837, pl. 43, fig. 1. (questionable) 1945 Orthoyoldia psammotaea (Dall). GARDNER, JULIA, Mollusca of the Tertiary formations of northeastern Mexico: Geol. Soc. Ameri­ca Mem. 11, p. 50, pl. 4, figs. 2, 3. 1946 Y oldia ( N uculana?) psammotaea Dall. HARRIS, G. D., The mollusca of the Jackson Eocene of the Mississippi embayment (Sabine River to the Alabama River) ; section 1, Bivalves: Bull. Am. Paleontology, vol. 30, no. 117, pp. 57_.58 (part), pl. 13, fig. 20. Origi,nal description.-Claiborne sands, at Claiborne, Alabama; Burns. Shell smooth, or with faint incremental lines, inequilateral with low beaks, the dorsal and ventral margins subparallel; valves elone:ated, rounded in front and behind, the posterior part somewhat compressed and attenuated; anterior end with a moderate gape; lunule and escutcheon elongated, very narrow, almost linear. Lon. 21, alt. 9, diam. 6 mm. This species is representPd bv two specimens with the valves closed and filled with a rather hard matrix, so that the hin~e characters are in­accessible. It is clearly distinct from any of the described species of the American Eocene, and peculiar in its elo~ated solenoid form. It can­not be confounded with Y. clai:bornensis Conrad, from the same horizon. It would find a p}ace in the section Ortho1yoldia Verrill. [Dall, 1890/1903, p. 596.] Revised description.-S.hell to about 25 mm long, spatulate-elongate (height is 40 to 50 percent of length), moderately to strongly inflated (width of valve is 29 to ·37 percent of height). Umbones somewhat anterior, at 0.35 to 0.45 of length of valve. Posterior end slightly narrower than an­terior end. Ventral margin nearly straight from below umbo to near the posterior end. Gardner (1945, p. 50) counted 12 to 15 anterior and about 18 posterior teeth on material from Texas and Mexico. Tex· as specimens of this species at hand have as many as 25 anterior and 30 or more posterior teeth. A topotype right valve has 22 anterior and 24 posterior teeth. Adductor muscle imprints relatively large and irregular in outline. Pallial line ob­scure; pallial sinus deep, wide, and U­shaped. Outer surface covered with very low and overlapping lamellae, 10 to 20 per mil­limeter, evanescent toward the extremities, tending to bifurcate and coalesce again. Dimensions.-The following Stone City specimens were measured in millimeters: WIDTH BED VALVE LENGTH HEIGHT OF.VALVE (w) Left 13.5 ·5.0 1.8 Left 7.8 3.7 1.2 (u) Right . 20.5 9.0 3.0 Left 20.4 8.7 2.5 Right 14.0 5.7 2.1 Right 12.0 5.8 1.4 Left 8.7 4.3 est. 1.5 (s) Right 12.7 est. 5.3 1.7 Left 17.5 7.6 (p) Left 12.0 4.8 2.4 est. Right 9.5 4.2 1.3 (d) Right 19.1 7.8 3.0 Right 18.0 7.4 2.2 est. Right 15.5 6.2 1.9 Average 14.4 6.2 2.0 Dall's holotype as given by Dall Double 21.0 9.0 6.0 (both) Remarks.-Dall's statement that 0. psammotaea Dall came from the Claiborne sands, now known as the Gosport sand, was pointed out as incorrect by Harris (1919, p. 72). Harris indicated that it came from the St. Maurice calcareous clays at the base of Claiborne Bluff, which are now known as the Cook Mountain (or upper part of the Lisbon) formation. Gard­ner ( 1945) , p. 50) confirmed the correc­tion. The Orthoyoldias from the various stratigraphic levels of the Claiborne group are all very similar; hence the species is interpreted broadly. In addition to the Stone City locality, specimens of 0. psam­motaea Dall, sensu lato, are known from the Cook Mountain formation of the Little Brazos River, Brazos County, and from the Viesca member of the W eches formation at Smithville, Bastrop County, Texas (Bur. Econ. Geology localities 21-T-l and 11-T-2, respectively). Specimens from all three localities have a sharper antero-dor­sal corner than that shown by Dall's pen· and-ink drawing (1890/1903, pl. 34, fig. 20). Another difference is po~ibly in the sculpture: The Texas individuals have def­inite concentric impr~ed lines, but the Alabama individuals were described as smooth or with incremental lines only. However, a right valve topotype from the Venericardia densata bed at the water lev­el beneath the bridge at Claiborne, Mon­roe County, Alabama, has a sharper an­ tero-dorsal corner than that shown by Dall's drawing and also impressed concen­tric lines. The Weches form has the strong­est sculpture and the Cook Mountain form the feeblest. The Stone City individuals are intermediate as to sculpture as well as to stratigraphic position. Two so-called varieties of Orthoyoldia psammotaea Dall were described by Har­ris (1919, p. 73, pl. 25, figs. 30, 31) : var. viv'ianensis from Vivian, Caddo Parish, northwestern Louisiana, and var. orange­burgensis from 5 miles north and north­west of Orangeburg, Orangeburg County, South Carolina. According to the geologic map prepared by Wallace (1946), the following formations occur in the vicin­ity of Vivian: Wilcox group, Reklaw and Queen City formations of Claiborne group, and Quaternary deposits. Of these the Reklaw is most likely to contain fossils. The Orangeburg variety is from the McBean formation (Cook Mountain equivalent), Claiborne group, Middle Eo­cene. The "variety" orangeburgensis is like typical psammotaea except that it has concentric undulations. The "variety" viv­ianensis has much more prominent beaks and stronger sculpture than psammotaea. We are considering these two varieties as ill founded until better information is ob­tained. An apparently very similar form was described from Claiborne, Alabama, by Conrad (1848b, p. 131, pl. 14, fig. 22) under the name N ucula claibornensis Conrad. The figure drawn by Conrad is unreliable and the specimen cannot be located. Whether it came from the Gos­port sand or the Lisbon formation is un­known, although Harris (1919, p. 72) and Dall (1890/1903, p. 596) made some conjectures. In view of the lack of reliable information on Nucula claibornensis Con­rad, it is considered a dubious species. Type data.-Dall's holotype, no. 129799, in U.S. National Museum, Wash­ ington, D. C. Type locality.-Base of bluff at Clai­ borne, bluff on left hank of the Alabama River, T. 7 N ., R. 5 E., west-central Mon­ roe County, Alabama. Cook Mountain (or upper part of the Lisbon) formation, Clai · borne group, Middle Eocene. Geologic horizon.-As interpreted here the species ranges from the Viesca mem­ ber of the Weches formation to the Cook Mountain (or upper part of the Lisbon) formation, Claiborne group, Middle Eo­ cene. Class FILIBRANCHIA Order PRIONODONTIDA Superfamily ARCICAE Family ARCIDAE Subfamily ARCINAE Genus ARCA IJnne, 1758 Autkor.-Linne, Carl (1758) Systema naturae, etc., ed. 10, vol. 1, pp. 693-695. Type species.-Arca noae Linne. Type designation.-Vnder suspension of the Rules, the name Arca Linnaeus, with Arca noae Linnaeus, 1758, as the type species, was added to the Official List of Generic Names in Zoology (Opinions and declarations rendered by the Internal. Comm. Zool. Nomenclature, vol. 3, pt. 8, pp. 93-108, Opinion 189, 1945). . First description of type species.- Linne (1758, p. 693) . Compare Dodge (1952, pp. 143-144). Type locality and horizon of type spe­ cies.-Living in the Mediterranean Sea. Generic description.-Shell to about 110 mm long, elongate (height is 34 to 52 per­cent of length) , strong I y inflated (width of valve is 40 to 50 percent of height). Umbones anterior (at 0.29 to 0.36 of length of valve) , conspicuous, far apart, prosogyrate. Anterior end rounded or pro­duced into a wing. Posterior end has an alate rostrum set off by a radial groove and keel. Ventral margin arcuate but hav­ing a concavity at the position of the byssal gape of the valves. Cardinal area long, wide, triangular, bearing incised chevron-shaped ligamental grooves. Hinge long, straight, having t~o series of very many small teeth: anterior teeth almost vertical, posterior teeth be­coming larger and more oblique distally, chevron-shaped near distal end; those proximal of the chevrons consist of the lower limbs of the chevrons only, those distal of it consist of the upper limbs only. Ligament amphidetic, finely striate per­pendicular to the hinge line. Pallial line simple, well defined. Sculpture consists of radial ribs, com­monly in alternating strength, restricted to the medial part of the shell in some spe­cies or covering the whole shell. Periostra­cum prominent, partly coarsely tufted. Subgenus ARCA Linne, 1758 Subgeneric description.-Anterior end of shell not produced. Ligamental chev­ron-shaped grooves disconnected at apex; ligamental areas forming a flat horizontal surface at hinge. Range of subgenus.-Reinhart (1943, p. 11) indicates a Cretaceous to Recent range of Arca s. s.; whether it is known below the Cretaceous is not distinctly stat­ed by him. In the Tertiary of the Gulf of Mexico basin, Arca s. s. has not been re­covered from the Paleocene, and the earli­est species known is A. (A.) hatchetigbeen­ sis Harris from the Hatchetigbee f orma­tion, Wilcox group, Lower Eocene. ARCA (ARCA) PETROPOLITANA Stenzel & Krause, n. ap. Pl. 5, figs. 1-4 Description.-Shell 11.6 mm long, elongate (height is 52 percent of length) , strong I y inflated (width of valve is 50 per­cent of height). Umbo anterior, at 0.26 of length. Anterior margin rapidly swings back from hinge line in a rounded curve. Posterior end narrowly rostrate and very sharply keeled. Keel end projects farther than end of the wing. No umbonal sul­cus present. Ventral margin: broadly arcu­ate, nearly rectilinear at the byssal gape, which is not clearly indicated. Sculpture consists of numerous radial ribs covering the entire disk; ribs round­ed in cross section; where growth lines cross them the ribs are_ either beaded or have overlaps like roofing tile; the ribs on the anterior end are stronger than those at the ventral margin; at the anterior half of the ventral margin smaller secondary ribs are intercalated bet ween the larger ones; toward the end of the rib situated on the posterior keel the prominent, radially elongate nodes of that rib are bifid with the dividing groove very narrow; there are about 7 high radial ribs on the ros­trum, dorsal of the keel, and their inter­spaces are wider than the ribs. _Growth lines abundant and somewhat raised. Dimensions.-Length 11.6 mm; height 6.0 mm; width of valve 3.0 mm; height of umbo above hinge line 2.0 mm; length of hinge 10.7 mm. Remarks.-The species is very rare; only a young left valve has been found. Arca s.s. is very rare in the Eocene of the Gulf Coastal Plain; the only other species known is A. (A.) hatchetigbeensis Harris from the Hatchetigbee formation, Wilcox group, Lower Eocene, of Hatchetigbee Bluff, Washington County, Alabama. The latter species has finer ribbing than the Stone City Arca, has a clearly indi­cated byssal gape and umbonal groove, and lacks the sharp keel and posterior emarg:nation of A. (A.) petropolitana Stenzel & Krause, n. sp. During the photographing of the mono­type the posterior projection was broken off and lost, and figure 4 of Plate 5 is the only figure giving the original out­line before breakage. Typ~ data.-The monotype, a left valve, is at the Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Stone City Bluff. Geologic horizon.-The single valve is from bed (f) of the Stone City section, Claiborne group, Middle Eocene. Genus BARBATIA Gray, 1842 Author.-Gray, J. E. (1842) Synopsis of the contents of the British Museum, ed. 44, p. 81. Type sp2cies.-"A. barbata"=Barba­tia ( Barbatia) barbata (Linne). Type designati.on.-Subsequent by Gray, J. E. (184.7) A list of the genera of recent Mollusca, their synonyma and type3: Zoo I. Soc. London Proc. 184 7, pt. 15, p. 197. First description of type species.­ Linne, Carl ( 1758) Systema naturae, etc., ed. 10, vol. 1, p. 693. Compare Dodge (1952,pp. 144-145). Typ~ locality and horizon of type spe­ c;es.-Living in the Medi:erranean Sea. Generic description.-She!l to about 110 mm l3ng, elongate (height is 53 to 77 percent of length), somewhat irregular in ou~line, oval or mytiliform, moderately to strongly inflated (width of valve is 29 to 47 percent of height). Umbones consider­ably anterior (at 0.11 to 0.31 of length), not greatly conspicuous, close together, prosogyrate. Anterior end rounded. Pos­terior end rounded or angulated by a pos­terior radial keel. Ventral margin some­what irregular with one or several con­cave parts, one of which marks the narrow hyssal gape. Valve commissure commonly uneven at basal margin. Cardinal area either long, narrow, tri­angular, bearing 5 or more incised chev­ron-shaped ligamental grooves having their obtuse apices under the umbo; or the part of the area anterior of the um­bones greatly reduced and obscure, hence only the posterior halves of the ligamental grooves plainly developed. Hinge straight, having two series of teeth. The distal teeth at both ends are large, consist of only the upper limb of the chevron, and are in­clined so as to converge toward venter; teeth under umbo very short, vertical, ef­f(!ced in some aduts. Ventral margin of valves finely fluted at pallial line. Sculpture consists of narrow radial ribs, usually beaded, either covering the entire disk uniformly or wholly or partly miss­ing on postero-dorsal part above the pos­terior radial keel r 1b. Range of genus.-Jurassic to Recent according to Reinhart ( 1935, p. 21). Subgenus BARBATIA Gray, 1842 Subgeneric description.-Shell to about 110 mm long, elongate (height is 53 to 77 percent of length) , oval or mytilif orm, somewhat irregular, moderately to strong­ly inflated (width of valve is 29 to 4 7 per­cent of height). Umbones considerably an­terior (at 0.15 to 0.27 of length of valve) . Posterior end rounded and without keel. Cardinal area with well-developed chevron-shaped grooves. Sculpture nearly uniform over entire disk. Range of subgenus.-Eocene to Recent according to Reinhart ( 1935, p. 21) . Remarks.-The two subgenera Barba­tia and Cucullaearca are closely related. As understood here Cucullaearca is char­acterized by a posterior radial keel which bears a narrow, high, prominent, serrate­ly beaded rib and, in some species, by the lack or partial lack of ribs on the postero­dorsal part of the valve above the keel. The subgeneric characteristics of Cucul­laearca listed by Reinhart (1935, p. 27), namely, large byssal gape, wide grooved ligamental area which usually separates the anterior teeth widely from the pos­terior ones, widened posterior end, and fairly heavy shell, are merely signs of ad­vanced age of some individuals and in our opinion are not subgeneric distinguishing characters. The subgenus Cucullaearca was proposed by Conrad ( 1865a, p. 11) , and its type species is Barbatia ( Cucul­laearca) cuculloides (Conrad), 1833, pre­sumably from the basal bed, the Dellet glauconitic sand (Stenzel, l 9S2·b, p. 41) , of the Jackson group, Upper Eocene, of Claiborne Bluff, Alabama. BARBATIA (BARBATIA) UXORISPALMERI Stenzel & Krause, n. sp. Pl. 5:i figs. 5-10 1860 Cibota mississippiensis (Conrad). GABB, W. M., Descriptions of new species of American Tertiary and Cretaceous fossils: Acad. Nat. Sci. Philadelphia Jour., ser. 2, vol. 4, p. 387, pl. 67, fig. 58. Not Byssoarca mississip piensis Conrad, 1848. 1924 Arca ludoviciana Harris. DEUSSEN, ALEX­ANDER, Geology of the Coastal Plain of Texas west of Brazos River: U. S. Geol. Survey Prof. Paper 126, p. 67. Not Arca ludoviciana Harris, 1919. 1931 Arca (Barbatia) cuculloides Conrad var. ludoviciana Harris. RENICK, B. C., & STEN­ZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. Description.-Shell to 40 mm long, elongate (height is 57 to 71 percent of length) , moderately to strongIy inflated (width of valve is 29 to 47 percent of height). Umbones anterior, at 0.17 to 0.27 of length of valve. Anterior margin round­ed. Posterior margin rounded and vari­able, in some individuals as narrow as the anterior, in others much more extended. Ventral margin variable, in most indi­viduals as a whole fairly straight but with several concave places or in some individ, uals deeply concave. Umhonal sulcus broad and shallow, ending in a narrow byssal gape at one of the concavities of the ventral . margin. Sculpture consists of numerous radial ribs covering the entire disk; ribs round­ed in cross section; where growth lines cross them they are beaded; the 9 ribs on the anterior end are slightly larger and their interspaces are as wide or wider than the ribs; ribs on the posterior end are wider but not higher and most of them split into closely spaced ribs sep­arated by a shallow and narrow inter­space which widens and deepens gradually during growth; the interspaces of the ribs on the posterior end are wider than those of the main part of the disk but are not wider than the ribs they separate; new ribs are added in various places, particu­larly on the posterior half of the valve, by intercalation of finer ribs or splitting of larger ribs; the intercalated ribs grad­ually reach the same size as their neigh­bors. Dimensions.-The foil owing type speci­mens were measured in millimeters: WIDTH BED VALVE LENGTH HEIGHT OF VALVE (x) Left 30.0 17.5 8.5 Right 29.5 18.8 7.0 Right 28.5 19.0 5.5 (u) Right 25.7 16.6 6.5 (s) Right 40.0 25.0 10.0 Right 31.0 14.8 7.0 (holotype) Left 29.0 .20.6 6.0 Left 27.0 17.0 6.0 Left 27.0 16.0 6.4 Left 26.6 16.0 5.4 Left 26.0 16.5 5.8 Right 25.7 14.7 6.4 Left 22.5 14.5 5.5 Left 22.0 14.3 5.0 Right 21.0 14.0 4.0 Right 20.0 13.0 4.0 Right 17.0 10.7 4.0 Right 15.3 9.4 3.3 Right 13.0 8.0 2.7 Right 7.3 4.5 1.4 (d) Left 21.2 13.0 4.4 Average 24.1 14.9 5.5 Remarks.-The Stone City species Barbatia (Barbatia} uxorispalmeri Sten­zel & Krause, n. sp., has been confused with one, or possibly several, other species. It is most commonly confused with Barba­tia (Cucull (part). HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleonto1o~, vol. 6, pp. 40-41, pl. 18, fig. 14? [not pl. 18, fiQ;s. 11-13]. 1924 Trinacria pulrhra Gabb (part). DFus~EN, ALE"'rne on the Brazos River, Tex~s: Univ. Texas Bull. 3101, p. 104, nnt p. 108. 1945 Halonanus p1ilchrus (Gabb). GARDNER, JULIA, Mollusca nf the TP-rtiarv formatinns of northeastern Mexico: Geol. SO{". AmPrira Mem. 11, po. 51-52. pl. 1, figs. 2 (?), 4 ( ? ) ; pl. 7' fig. 13 ( ? ) . Original, description.-Subquadrangular; beaks small, incurved; umbonal s1ope nearly straight; anterior margin rounded, basal arcuate, posterior subangnlar; surface marked hy numerous radiat­ing and transverse lines; edge crenate within; posterior muscular scar subtriangular, anterior subrhomboidal. Dimensions.-Length .27 in., width .35 in. [ Gabh, 1860, p. 388.l Revised description.-Shell to 12 mm long, cuneate-rectangular, strongly in­flated (width of shell is 75 percent of height and 55 percent of length). Um­bones slightly anterior (at 0.45 of length). Anterior smoothly rounded, posterior sub­angular; umbonal ridge rounded, well defined, umbonal slope broad, nearly flat; postero-dorsal margin broadly arcuate; ventral margin gently convex. Anterior series of about 10 to 17 teeth, posterior series of about 8 to 15 teeth. Sculpture consisting of Iow, narrow, concentric ribs separated by broad, shal­low interspaces which are 2 to 3 times wider than the ribs; and rounded, closely­spaced radial ribs, 'vhich are slight! y stronger than the concentric ribs, devel­oped best toward the ventral margin, sep­arated by rounded interspaces of nearly equal width, and are slightly nodulated where the concentric ribs cross them. In­ner margins crenulate, crenulations ex­tending from the antero-dorsal margin to the dorsal margin at the posterior ex­tremity. Dimensions.-The following v a Ives from Stone City Bluff were measured in millimeters: POSITION WIDTH OP UMBO 01" IN PERCF.NT BED VALVE LENGTH HEIGHT VALVE OF LENGTH (x) Right 10.1 7.4 2.9 0.45 (w) Right 9.4 6.6 2.6 0.47 Left 9.2 6.5 2.5 0.43 (u) Left 9.2 6.8 2.8 0.46 Right 8.1 6.4 2.3 0.44 Left 7.0 5.2 1.6 0.46 (s) Left 7.4 5.7 2.3 0.46 Left 6.5 5.1 2.0 0.48 (d) Right 7.5 5.7 2.1 0.45 Right 5.1 4.0 1.4 0.49 Left 4.3 3.3 1.2 0.42 (c) Left 8.1 6.2 2.6 0.44 Left 7.9 5.9 2.4 0.44 Right 5.9 4.4 1.4 0.42 Average 7.5 5.7 2.2 0.45 Gabb' s types (Measured by Gabb, probably the figured 1 ectoholotype) teft 8.9 6.9 (l\ileasured by Stenzel, one of the paratypes) Left 8.4 7.3 2.1 Type data.-The types are at the Acad­emy of Natural Sciences of Philadelphia. The entry book under No. 13261 states there should be four type specimens, but Stenzel, in 1948, found only three remain­ing. The missing specimen is believed to be the left valve figured by Gabb ( 1860, pl. 67, figs. 55, 55a) and is here desig­nated the lectoholotype. Type locality.-Presumably Stone City Bluff. Geologic horizon.-Stone City beds, Claiborne group, Middle Eocene. For dis­ tribution in the individual beds of the Stone City section, see table 3. PACHECOA (PACHECOA) SABINICA (Harris) Pl. 6, figs. 17-20 1919 Trinacria pul,chra var. sabinica HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, p. 41, pl. 18, figs. 15, 16. [June 30] 1931 Trinacria declivis Conrad. RENICK, B. C., & STENZEL, H. B., The lower Claiborne on th~ Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. 1943 Halorianus pulcher (Gabb). REINHART, P. W., Mesozoic and Cenozoic Arcidae from the Pacific Slope of North America: Geol. Soc. America Spec. Paper 47, p. 79, pl. 2, figs. _ 16-18. Original, description.-On the Sabine River particularly near .the township line between 4 and 5 north, though on the Texas side, there is a marked form of pul,chra, much more carinate and cuneiform and of much smaller dimensions than typical specimens. In fact, in outline it cl?Sely approaches ledoides of Meyer. But, as will be seen by the illustrations it is really not at all closely related to that species. [Harris, 1919, p. 41.] Revised description.-Shell to 10 mm long, cuneate-triangular, strongly in­flated (width of valve is about 38 percent of height) . Umbones slightly anterior (at 0.45 of length). Anterior smoothly round­ed, posterior cuneate, postero-dorsal mar­gin nearly straight, ventral margin gently convex. Umbonal ridge well defined, rounded; umbonal slope slightly concave. Anterior series of about 10-12 hinge teeth, posterior series of about 8-10 teeth. Sculpture of low, broad, rounded, close-· ly spaced concentric ribs crossed by low, rounded, widely spaced radial ribs, which are best developed along the umbonal ridge hut are obsolescent elsewhere· ra­ dial ribs not nodulated at the intersectlons with the concentric ribs. Concentric in­ terspaces very narrow, about 1/4 to 1/3 as wide as the ribs; radial interspaces wide, about twice the width of the ribs. Inner margins smooth to crenulate, depending on the individual variation of the radial ribbing. Dimensions.-The following valves from Stone City were measured in millimeters: POSITION WIDTH OFUMBO OF IN PERCENT BED VALVE LENGTH HEIGHT VALVE OF LENGTH (c) Left 7.9 5.7 2.1 0.43 Left 6.8 5.3 2.0 0.46 (d) Right 9.0 7.0 2.6 0.48 Left 8.1 5.9 2.2 0.42 Left 7.8 5.8 2.0 0.45 Left 7.2 5.3 2.0 0.42 Right 7.0 5.3 2.0 0.4.4 Right 6.9 5.2 1.8 0.45 (p) Right 7.2 5.3 2.0 0.45 Left 6.1 4.7 1.8 0.49 (s) Right 7.9 6.0 2.1 0.44 Right 7.9 5.9 2.6 0.43 Right 6.6 5.1 1.8 0.47 Right 6.6 5.1 1.7 0.47 Left 5.9 4.4 1.7 0.46 Left 5.1 3.9 1.4 0.49 Double valve 6.4 4.9 3.5 0.47 Average 7.1 5.3 2.0 0.45 Lectotype (Harris, 1919, pl. 18, fig. 16) Left 7.0 4.6 est. Type data.-The lectotype, a ]eft valve, is at the Paleontological Research Institu­tion, Ithaca, New York. Type locality.-Harris (1919, p. 41) stated that his specimens were found ''On the Sabine River, particularly near the township line between 4 and 5 north, though on the Texas side ...." This loca­tion is quite similar to that given by Har­ris for his Glycymeris sabinensis Harris (1919, p. 51), which we have discussed previously on page 61. There are several fossiliferous localities on the Texas bank of the river in this vicinity; but only two carry P. ( P.) sabinica (Harris) , and of these two only Bur. Econ. Geology local­ity no. 201-T-15 carries a great abundance of this species. Hence we .assume that the type locality is on the right bank of the Sabine River at the west end of the long west-east reach opposite section 35, T. 5 N., R. 13 W. in Sabine Parish, Louisi­ana, 0.65 mile northwest of Crane Pond and 1.8 miles air-line distance northwest from the U. S. Geological Survey bench mark 164 at the road fork known as Co­lumbus, Louisiana. This is locality 21 of Veatch (1902, p. 129, pl. 33) and Bur. Econ. Geology locality no. 201-T-15 ·Sa­bine County, Texas. ' Geologic horizon.-Restricted to the Stone City beds, Claiborne group, Middle Eocene. For distribution in the individual beds of the Stone City Bluff, see table 3. PACHECOA (PACBECOA) SMITBVILLENSIS Stensel & Twining, n. •P• Pl. 6, figs. 7-9 1919 Trinacria pul,chra Gabb (part). HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, pp. 40-41, pl. 18, figs. 11-13. [Not pl. 18, fig. 14.] 1924 Trinacria pulchra Gabb (part). DEUSSEN, ALEXANDER, Geology of the Coastal Plain of Texas west of Brazos River: U. S. Geol. Survey Prof. Paper 126, p. 67. [Those list­under "N."] 1931 Triruzcria pul,chra Gabb (pan). RENICK, B. C., & STENZEL, H. B., The lower Clai­borne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 108. [Not p. 104.] Description.-Shell to 15 mm long, cu­neate-rectangular, strongly inflated (width of shell 75 to 80 percent of height and 55 to 60 percent of length) . Umbones median to suhmedian (at 0.48 to 0.54 of length). Anterior smoothly rounded, posterior nar­rowly rounded to subangular; umbonal ridge rounded, well defined; umbonal slope broad, nearly flat; postero-dorsal margin subangular to arcuate; ventral margin usu­ally gently convex but tending to very slightly sigmoidal in some shells as the result of the development of a broad, shallow sulcus just anterior to the um­bonal ridge. Anterior and posterior series of hinge teeth nearly equal; about 10 to 15 teeth in each series. Sculpture of concentric and radial ribs with varying patterns on different parts of the shell. In the neanic stage the con­centric ribs are broad and flat-topped leaving narrow impressed interspaces be­tween them; the radial ribs are low, nar­row, rounded, widely spaced and show up best in the impressed grooves. In the ma­ture stages the concentric ribs are low, broad, widely spaced, steeper on the um­bonal side, gently sloping toward the ven­ter; the radial ribs are still mostly con­fined to the ventral slope of the concen­tric ribs. Near the valve margins the con­centric ribs become more closely spaced, narrower, and more rounded; the radial ribs are stronger, and a well-defined retic­ulate pattern is produced. In the final growth stages of senile shells the concen­tric sculpture is reduced to simple growth lines, but the radial ribs continue to the margin. Inner margins crenulate. Dimensions.-The following types were measured in millimeters. All are double-valved individuals with the excep­tion of two single valves as indicated: POSITION WIDTH OFUMBO OF IN PERCENT VALVE LENGTH HEIGHT VALVE OF LENGTH Right 12.9 9.6 4.4 0.50 (holotype) Left 14.1 10.5 5.5 0.50 (senile) Double 14.7 10.9 9.8 0.49 13.1 9.4 8.2 0.50 12.5 9.5 7.5 0.49 12.2 9.6 6.6 0.50 12.2 9.3 6.9 0.49 12.1 9.2 8.0 0.50 11.0 8.4 6.6 0.51 10.2 7.9 5.9 0.50 10.2 7.7 5.6 0.50 9.9 7.7 5.1 0.05 9.8 7.7 5.4 0.50 9.8 7.3 5.6 0.49 9.5 7.2 5.3 0.48 9.5 6.9 5.0 0.48 9.2 7.2 5.7 0.53 9.1 7.1 5.3 0.53 9.0 7.6 5.7 0.53 8.9 6.8 4.7 0.50 8.7 6.8 5.2 0.52 8.0 6.5 4.9 0.49 8.0 6.2 5.3 0.54 Average 10.4 7.9 6.1 0.50 Type data.-Holotype (right valve) and 617 paratypes ( 297 right valves, 297 left valves, and 23 double-valved individuals) are at the Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Blu:ff on right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. Geologic horizon.-The types are from the Viesca member of the W eches f orma­tion, Claiborne group, Middle Eocene. PACHECOA (PACHECOA) CATONIS SteDJtel & Twining, n. •P• Pl. 6, figs. 12-14 Description.-Shell to about 15 mm long, cuneate-rectangular, nearly as big~ as long, strongly inflated (width of valve is 35 percent oi height and 55 percent of length). Umbones nearly median (at 0.48 of length). Anterior smoothly rounded, posterior subangular; umbonal ridge rounded, not prominent, umbonal slope broad; postero-dorsal margin subangular, ventral margin gently convex. Hinge _broad, smoothly arcuate, ante­rior series of about 14 to 16 teeth, poste­rior series of about 12 to 14 teeth. Sculpture consisting of fine, narrow concentric threads separated by broad, shallow interspaces, which are 2 to 3 times wider than the threads, and very fine and narrow radial threads, slightly finer than the concentric ones and spaced about the same as the concentric threads, produc­ing a fine reticulate patt~rn over the main part of the disk. The radial threads are slightly stronger on the posterior slope. In the adult stage a very fine secondary radial thread is intercalated between each pair of primary radial threads. This secondary radial thread is commonly short and re­stricted to the dorsal slope of the concen­tric threads and evanesces in the inter­space; hence each secondary ray shows as a series of discontinuous threadlets. The radial sculpture is slightly stronger and wider spaced on the part of the shell pos­terior of the umbonal ridge. Inner mar­gins smooth. Dimensions.-The following types were measured in millimeters: POSITION WIDTH OFUMBO 01-· IN PERCENT VALVE LENGTH HEIGHT VALVE OF LENGTH Rio-ht 12.7 10.8 3.8 0.47 (holotype) Right 12.0 10.6 3.3 0.49 Left 7.9 6.7 2.1 0.47 Right 7.2 5.6 1.7 0.49 Rio-ht 5.2 4.4 1.4 0.48 ~ Right 5.0 4.1 1.2 0.46 Average 8.3 7.0 2.3 0.48 Type data.-Holotype (right valve) and 6 paratypes (one broken and 4 complete right valves and one left valve) are at the Bureau of Economic Geology, The Uni­versity of Texas, Austin, Texas. Type locality.-Caton's B!ufl, low bluff on left bank of Conecuh River, about 1,000 feet from Country Club road, that is, the road leading from Andalusia past_the Country Club to Prestwood Bridge, section 14, T. 4 N., R. 15 E., about 0.2 mile from Prestwood Bridge and about 3 miles west­northwest of Andalusia, Covington Coun­ty, Alabama. Geologic horizon.-The types are from the uppermost bed of the Tallahatta for­mation, Claiborne group, Middle Eocene. They are associated with Cubitostrea per­plicata (Dall) and Lopha johnsoni (Al­drich). Remarks.-The family Noetiidae is well represented in the Eocene of the Gulf and Atlantic Coastal Plain, by genera as well as by species. However, several species have been described from inadequate ma­terial and are in need of revision. P achecoa ( Pachecoa} microcancellata (Barry) in Barry & LeBlanc (1942, pp. 48-49, pl. 2, figs. 15-18) from the Sabine­town marl, Wilcox group, Lower Eocene, of Sabinetown, Sabine County, Texas, is apparently a Pachecoa of cuneate outline; its umbones are somewhat posterior in po­sition, and the nearly straight postero­dorsal and postero-ventral margins meet at an acute angle at the sharp umbonal ridge. Pachecoa (Pachecoa) catonis Stenzel & Twining is related to P. ( P.) declivis (Con­rad) and P. ( P .) decisa (Conrad) , but the · latter is more elongate and P. ( P.) declivis (Conrad) is usually more clearly cuneate. The radial ribs of P. ( P.) catonis Stenzel & Twining cover the entire valve and, al­though equally as fine, are sharper and better defined than those of P. (P.) declivis (Conrad) , which do not cover the median part of the valve. Very probably P. (P.) catonis Stenzel & Twining is the ancestor of P. (P.) declivis (Conrad) and perhaps also of P. (P.) decisa (Conrad). Pachecoa (Pachecoa} adamsi (Palmer) in Price & Palmer (1928, p. 25, pl. 7, figs. 1, 2, 5) is from the upper Queen City for­ 1.0ation, Claiborne group, Middle Eocene, at the mouth of Gazley Creek in Smith­ville, Bastrop County, Texas, Bur. Econ. Geology locality no. ll-T-38; it is ovate­rectangular and its umbones are situated far anterior, at 0.65 of the length; the umbonal ridge is rounded off, but parallel to it and above it is a sulcus; hence the posterior extremity is obliquely truncate with a more or less well-developed indenta­tion; the inner margins are not crenulated. This species has a very long but feebly de­fined escutcheon (Pl. 6, figs. 10, 11). Not­withstanding the statements by Price & Palmer (19~8) and by Plummer ( 1933, pp. 640, 644) the beds which contain these fossils are now known to he the uppermost part of the Queen City formation (com­pare Stenzel in Stenzel & Turner, 1940c, p. 75). Pachecoa (Pachecoa} smithvillensis Stenzel & Twining is most closely related to P. (P.) pulchra (Gabb), hut differs from the latter by its larger size, slightly greater inflation, slightly sharper umbonal ridge, more prominent concentric ribs and less prominent radial ribs. The two species are so closely related that it is highly prob­able P. ( P.) smithvillensis Stenzel & Twin­ing is the ancestor of P. (P.) pulchra (Gabh). Pachecoa ( Pachecoa} pulchra (Gabb) can be readily separated from P.(P.)sabin­ica (Harris), with which it is associated, by the more cuneate outline, the more nearly straight postero-dorsal margin, the lower and broader concentric ribs, and the much less well-developed, lower, and more widely spaced radial ribs of the lat­ter species. Also, most individuals of P. (P.) sabinica (Harris) have smooth in­terior valve margins, because the radial ribs are weak. In contrast, all valves of P. (P.) pulchra (Gabb) have crenulated interior margins. Pachecoa (Pachecoa} sabinica (Harris) ·is most closely related to P. (P.) smith­villensis Stenzel & Twining and P. ( P.) pulchra (Gabb) . Pachecoa (Pachecoa} decisa (Conrad) (1833b, p. 39; 1860, p. 297) from the Cook Mountain formation, Claiborne group, Middle Eocene, of Claiborne Bluff, JVIonroe County, Alabama, is one of the largest species of the genus, to 25 mm long, and has elongately ovate-cuneate out­line; the posterior margin is nearly straight and slopes steeply to the terminus of the well-defined umbonal ridge; the broadly arcuate hinge carries small teeth, the an­terior series of teeth is longer than the posterior one; the sculpture is of low, nar­row, rounded, widely spaced concentric ribs and widely spaced radial ribs, which are interrupted where they are crossed by the concentric ribs; the inner margins are devoid of crenulations. Here probably be­longs the "Trinacria decisa Conrad, var. abbreviata Harris" ( 1919, p. 41, pl. 18, fig. 19), and the varietal name appears to be unnecessary. Pachecoa ( Pachecoa} declivis (Conrad) ( 1833b, p. 39; 1860, p. 297' pl. 4 7' fig. 12) from the Cook Mountain formation, Claiborne group, Middle Eocene, of Clai­borne Bluff, Monroe County, Alabama, is a large species, to 25 mm long; its outline is cuneate-rectangular tv subtrigonal, near­ly as high as long, the postero-dorsal mar­gin is straight and slopes steeply, the hinge is strongly arched and has a strong curve in the anterior series of teeth; the sculpture is of fine, closely spaced concentric ribs and iii -defined radial ribs, which are con­fined to the posterior part of the shell ; the inner margins are devoid of crenulations. Pachecoa ? (Subgenus?) lisbonensis (Harris) ( 1919, p. 45, pl. 19, figs. 16, 17) from the Lisbon formation, Claiborne group, Middle Eocene, of Lisbon Bluff, Monroe County, Alabama, has nearly cir­cular outline and is almost as high as it is long. Pachecoa {Subgenus?} ovalis (Harris) ( 1919, p. 43, pl. 19, figs. 9, 9a) from the Cook Mountain formation, Claiborne group, Middle Eocene, of Claiborne Bluff, Monroe County, Alabama, has an ovate outline and is nearly equilateral; all mar­gins are broadly rounded, the long hinge is smoothly arcuate; the sculpture is of very fine and closely spaced radial ribs and more prominent concentric growth lines. The "Trinacria decisa Conrad, var. carolina Harris" ( 1919, p. 41, pl. 19, figs. 18, 18a) remains ill understood. It is re­corded from "Three miles and six miles W. N. W. of Orangeburg, S. C." from the Mc­Bean formation, Claiborne group, Middle Eocene. Pachecoa (Stenzelia} ellipsis (Lea) ( 1833, p. 78, pl. 3, fig. 56) from the Gos­port sand, Claiborne group, Middle Eo­cene, of Claiborne Bluff, Monroe County, Alabama, has a regular oval outline and very .feeble sculpture; the umbones are only slightly anterior in position; all mar­gins are broadly _and well rounded; the sculpture is of faint, rounded, closely spaced concentric and radial ribs distribu­ted over the entire disk but better devel­oped at both ends; the inner margins are devoid of crenulations. The species is the most common of the Noetiidae in the Gos­port sand. Pachecoa (StenzeUa) perplana (Con­rad) has been discussed under Remarks to the subgenus Pachecoa. Pachecoa (Pachecoa?} led o ides :. (Meyer) ( 1886a, p. 79, pl. 1, fig. 20) from the Gosport sand, Claiborne group, Middle Eocene, of Claiborne Bluff, Monroe Coun­ty, Alabama, was inadequately described, and the solitary type valve is a ju~enile. Whether the revised description of this species given by Cossmann (1893, pp. 15­16) is really based on specimens of this species is open to question. The same ap­plies to the interpretation and figures given by Harris (1919, pp. 31-33, pl. 18, figs. 10, lOa). Pachecoa? (Pachecoa?) pectuncularis (Lea) (1833, pp. 81-82, pl. 3, fig. 60) from the Gosport sand, Claiborne group, Middle Eocene, of Claiborne Bluff, Mon­roe County, Alabama, was also described from a single juvenile valve only about 3 mm long. Whether the adults ascribed to this species by Harris (1919, pp. 42-43, pl. 19, figs. 7-8) are correctly placed is open to question. Cossmann (1893, p. 17) was convinced he had.'received a small valve of this species and that it was an Arca, sensu lato. "Pectunculus" corbuloides C o n r a d ( 1833b, p. 40; 1860, p. 297) from Clai· borne Bluff, Monroe County, Alabama, may be based on a Pachecoa, but it re­mains unfigured and unrecognizable, so indefinite is Conrad's description. Harris (1919, p. 39) seemed to believe on the basis of some labels in the Philadelphia Academy that this name applied to Pache-. coa (Pachecoa} declivis (Conrad), 1833, which has page priority in the same pub­lication. Nanohalus cossmanni (Dall) from the Gosport sand, Claiborne group, Middle Eocene, of Claiborne Bluff, Monroe Cm the Wal­nut(?) f ormati.on, Fredericksburg group, Lower Cretaceous (Middle Albian) , at the base of the bluff at the mouth of Santa Elena Canyon on the left bank of the Rio Grande, Big Bend National Park, Brewster County, Texas; closely related to (3) • Woods (1900, p. 100) regarded the fol­lowing species-/. flagellifera (Forbes), I. pUcata (J. Sowerby), I. perpl,icata (Etal­lon) , I. medus (D'Orbigny) , and I. icaun­ensis (De Loriol)-as well known repre­sentatives of this group, which he, how­ever, considered a special section of Mo­diola. He also intimated that I. gillieroni· (Pictet & Campiche), I. baini (Sharpe), I. ebrayi (De Loriol), and /. siliqua (Ma­theron) might belong here. The latter had already been referred to lnoperna by Con­rad (1875). However, some of the names given above may turn out to be synonyms as intimated by some of the authors cited. Therefore it is apparent that the genus Inoperna is not rich in species. The range of lnoperna is Whitbian to Maastrichtian. A later synonym of lnop­ erna is Pharomytilus Rollier (1914, p. 338) , the type species of which is Modiola pl,icata J. Sowerby (1819, p. 87, pl. 248, fig. 1) =Mitylus sowerbianus D'Orbigny (1850/52, vol. 1, p. 282) =Mitylus sower­ byanus D'Orbigny (1850/52, vol. I, p. 312) = lnoperna plkata (J. Sowerby), which is listed above. Conrad regarded his genus lnoperna as near allied to lnoceramus as shown by the name he gave. Stephenson placed the genus in the Mytilidae separate from Mo­dwlus, Crenella, and Lithophaga. Wade placed the genus under "Family?" under the superfamily Pteriacea, where he also placed the family Pernidae with the genus l~oceramus. Popenoe placed the genus, as did Stephenson, in the family Mytilidae. Cox ( 1940, pp. 70-71) in his discussion of this group placed lnoperna as a sub­genus under Modiolus. We regard Ino­ perna as closely related to Mauricia, be­cause it is so similar in shape and sculp­ture and possibly in hinge features. If these similarities are to be trusted Maur­ . . ' icia may wel1 be the last dwindling de­scendant of lnoperna. In that case one ought to consider M auricia as a subgenus ?f lnoperna. However, in view of the gaps in our knowledge of the hinge features of the latter we prefer to let Mauricia provi­sionally stand as a genus. . M?uricia and lnoperna are very sim­ilar in general shape and outline, position of the umbones, presence of an umbonal r!dge an? its shape, and in the corruga­tions which are restricted to the area be­tween dorsal margin and umbonal ridge. However, the two genera differ in that the Jurassic members of lnoperna have very many and comparatively fine corrugations, and the Upper Cretaceous members of that genus have fewer and somewhat broader corrugations, whereas Mauricia has still fewer and still broader corruga­ti_ons than even the Upper Cretaceous spe­cies of lnoperna. Also in lnoperna the cor­rugations clearly either bifurcate or trifur­cate or multiply by intercalation about halfway between the dorsal margin and the ~mbonal ridge; in Mauricia most corruga­tions do not seem to multiply in any way, but a very few do have slight indications of splitting before they flatten out near the ~mbonal ridge, noticeable only when specially searched for. The Jurassic spe­c~es of lnoperna, the Upper Cretaceous spe­cies of lnoperna, and the Eocene species of M auricia seem to form a progressive evolutionary morphological series. At no ti.me did the two genera have many spe­cies, and nearly all the species were un­common as to individuals. MAURICIA HOUSTONIA (Harris) Pl. 7, figs. 2-8 1895 M odiola houston.ia HARRIS, G. D., New and otherwise interesting Tertiary Mollusca from Texas: Acad. Nat. Sci. Philadelphia, P~oc. 1895, p. 46, pl. l, fig. 1. [April 9] 1898 Lithophaga? houstonia (Harris). DALL W. H., ~ontributions to the Tertiary faun~ of Flonda, etc. : Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, pp. 798, 801. 1919 Modiolus (Mauricia) houstonius Harris. HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, no. 31, p. 32, pl. 17, figs. 5, Sa. 1931 M odiolus houstonius Harris. RENICK, B. C., & STENZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. Original description.-General form of shell as floured· thin showin () concentric lines of growth 0 ' ' 0 h on the area below th~ umbonal ridge; above t e same with broad concentric undulations, becom­ ing ~ore nun1erous towards the umbones; an­ terior, radially striate. Localities.-Three miles northeast of Crockett, Houston Co.• Tex.; also five miles northwest of Orangeburg, S. C. Geological horizon.-Lower Claiborne Eocene. Type.-In Texas State Museum. [Harris, 1895b, p. 46.] Revised description (based on holotype and 2 other individuals) .-Shell to about 40 mm long, elongate (height is 40 to 53 percent of length), moderately to strongly inflated (width of double valves is 56 to 82 percent of height); umbonal ridge pro­nounced. Position of umbones far anterior, at 0.09 to 0.11 of length of valve; umbones tumid, prosogyrate, well developed but not rising much above hinge line. Posterior end well rounded and produced postero-vent­rally. Postero-dorsal margin gen:ly convex from the hinge line to posterior end. Dor­sal margin posterior of the umbo nearly straight, very long, and very finely crenu­late. Ventral margin almost straight, faint­ly concave at the posterior one-third. In­terior unknown. One of the three individuals is decorti­cated along the hinge; hence the seat of the ligament is visible on the internal mold. Ligament long (about 55 percent of length of valve), subinternal, situated in a narrow dorsal groove just below the dorsal margin of the valves. The broad concentric undulations stop at the margin of this groove; hence they fail to reach the dorsal margin of the valve by the width ( 1 mm) of the narrow dorsal groove in which the ligament is situated (see Pl. 7, fig. 8). Sculpture consists of broad concentric undulations, fine radial riblets, and growth lines. The broad, heavy concentric undula­tions foilow the growth lines from the hinge line to the umbonal ridge, where they flatten out rapidly and disappear without crossing the ridge. The radial rib-. lets are very fine, divaricating, headed slightly where growth lines cross them, and restricted to the anterior end ; they begin at a vertical line through the umbo. Another group of these riblets extends from the umbo along the umbonal ridge; these rib lets are obsolescent and fade out about 7 mm from the umbo. The crenula­tions of the dorsal margin posterior of the umbo are the ends of very short obso­lescent radial riblets, restricted to a band 1 millimeter wide and parallel to the dorsal . margin. Dimensions.-The following double. valve shells were measured in millimeters (compare fig. 10): LOCALITY LENGTH HEIGHT WIDTH Hurricane Bayou 27.0 11.5 9.5 (holotype) Stone City Bluff 40.0 est. 21.0 est. 11.8 36.3 14.7 10.8 Average 34.4 15.7 10.7 Remarks.-The most characteristic fea­ture of Mauricia houstonia (Harris) is its solenif orm outline produced by the nearly parallel dorsal and ventral margins, which are diverging at only a very slight angle. This species is very rare. All three in­dividuals are internal molds of the double valves \vith varying amounts of the shell adhering. The two individuals from Stone City may be from either the Stone City beds or the Wheelock member of the Cook Mountain formation. They were collected at Stone City Bluff before the section was divided by Stenzel (1936, p. 277) into the two formations. Type data.-Holotype, double valves, no. 145, Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Hurricane or Three-Mile Bayou, bluff on right bank, 0.3 mile up­stream from bridge on Crockett-Rusk county road, or Mail Route 1, 3.35 miles from courthouse at Crockett, in southeast corner of Young-Murchison 5531h-acre tract and H. F. Craddock 277.4-acre tract, southeast comer of Newell C. Hodge sur· ,-ey, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-2. Geologic horizon.-Hurricane lentil at base of Landrum member of Cook Moun­ tain formation, 30 to 50 feet above base of the formation, Claiborne group, Middle Eocene. The species occurs also in the Stone City beds questionably or the Whee­ lock member of the Cook Mountain forma­ tion of the same group. MAURICIA LEONIA Stenzel & Krause, n. sp. Pl. 7, fi~. i liquely elongate (height is 62 percent of length; oblique height is 48 percent of oblique length; see fig. 10), moderately in­ flated (width of one valve is 29 percent of height) ; um.bona} ridge very broadly rounded and much less pronounced than in M. houstonia (Harris). Position of um· ho far anterior, at 0.12 of length of valve. Posterior end broadly rounded and pro­ duced postero-ventrally. Postero-dorsal margin gently convex from hinge line to posterior end, considerably longer than in M. houstonia (Harris) resulting in a higher posterior half of the valve and an outline much more like Volsella than M. houstonia (Harris) has. Ventral margin almost straight, faintly concave at the pos­ terior one-third. Dorsal margin posterior of the umho straight, very long, not crenu­ late. Dorsal and ventral margins diverge at 22 degrees. Hinge edentulous. Ligamental groove ill defined, if at all present. Sculpture consisting of broad concen­tric undulations, fine radial riblets, and growth lines. The broad, heavy undula­tions are parallel with the growth lines, but restricted to the area between hinge and umbonal ridge as in M. houstonia (Harris). Radial riblets very fine, divar­icating, slightly stronger than in Af. hous­. toni4 (Harris) , and restricted to anterior .end as in the other species. The radial rib­lets extending from umho along the wn­bonal ridge as in the other species, but hardly noticeable. A few faint short curv­ing, divaricate riblets at the place where the straight dorsal margin bends down into the postero-dorsal margin. Dimensions.-The monotype, a single right valve, is 32.5 mm long, 20.3 mm high, and 5.9 mm wide; obliquely it is 34.7 mm long and 16. 7 mm high (com­pare fig. 10). .,.____Length---___.. Fie. 10. Outline of Mauricia, showing the length, height, oblique length (or greatest dimen­sion), and oblique height, xl.2 natural size. Remarks.-The new species Mauricia leonia Stenzel & Krause differs from M. houstonia (Harris) chiefly in its outline, which is more like that of V olsella, that is, the dorsal and ventral margins of the shell diverge at a larger angle toward the pos­terior. In addition the umbonal ridge is less conspicuous, being more broadly rounded. The one valve available has an irregu­lar break extending to near the umbo. This break was apparently acquired in life, be­cause it is healed over and shows only as a sort of step. Type data.-The monotype, a right valve, is at the Bureau of Economic Geol­ogy, The University of Texas, Austin, Texas. Type loca/,ity.-Middleton-Sulphur Springs School county road, right bank of dry north-flowing branch, being a right tributary of Boggy Creek, in woods about 200 feet below fence and tank and about 0.55 mile north of county road. Above­mentioned fence probably is the west line of the survey; in south corner of F. C. Wilson 100-acre tract, A. Richardson sur­ Bureau of Economic Geology, The University of Texas vey, Leon County, Texas; Bur. Econ. Geology locality no. 145-T-80 (compare Stenzel, 1939, pp. 269-270). Geologic horizon.-From a glauconitic shell breccia with clay-ironstone matrix in the Mount Tabor member of the Cook Mountain formation, Claiborne group, Middle Eocene. Order ISODO·NTIDA Superfamily PINNICAE Family PINNIDAE Genus ATRINA Gray, 1842 Author.-Gray, J. E. (1842) Synopsis of the contents of the British Museum, ed. 44, p . . 83. [Not seen.] Compare Iredale, 1913, p. 303. Type species.-"P. nigra" = Pinna nigra Dillwyn, 1817 = Pinna vexillum. Born 1780 =Atrina vexillum (Born). ' Type designation.-Subsequent by Gray, J. E. (1847) A list of the genera of recent Mollusca, their synonyma and types: Zool. Soc. London Proc. 184 7, pt. 15, p. 199. First description of type species.-Born, Ignatius (1780) Testacea Musei Caesarei Vindobonensis, p. 134, pl. 7, fig. 8. [not seen] Type locmity and horizon of type spe­ cies.-Living from the Red Sea to New Caledonia. Generic description.-Shell thin, fragile, composed of only two layers, an outer prismatic layer and an inner nacreous layer, large (to about 260 mm long), out­ line cuneate, moderately inflated, equi­ valve, very inequilateral, gaping narrowly at the posterior and venter; the byssal gape at the venter narrow and elongate. Umbones anterior and terminal. Anterior end cuneate, posterior end broadly round­ ed, dorsal margin straight or only slightly curved, ventral margin sigmoidal. Hinge straight, edentulous. Ligament external, narrow long (extending one­ half to two-thirds the length of the dorsal shell margin). Anterior adductor muscle imprint small, occupying nearly the entire narrow anterior point of the shell; pos­ terior adductor muscle imprint la~ge and confluent with that of the pedal retractor, about halfway between the ends of the shell and slightly nearer to the dorsal than to the ventral margin. Sculpture consists of low, rounded ra· dial ribs on which the growth squamae produce hollow squamous spines; concen· tric growth lamellae which are squamous where they cross the radial ribs; and low, broad concentric undulations, especially on the ventral .slope. Inner margins smooth. Range of genus.-Middle Eocene to Re­cent. Remarks.-Atrina differs from Pinna by the absence of the internal groove extend­ing from the anterior extremity of the shell to the base of the posterior adductor muscle imprint and dividing the nacreous layer of Pinna into two parts. Winckworth ( 1929, p. 280) states that this groove " ... is due to the point of attachment of the mantle, which is immediately ven­tral to the adductor muscle, and which does not secrete nacre at this point." In Atrina, which lacks this groove, the nacreous layer is entire. In Pinna the ventral margin is generally straight or only slightly curved, resulting in an acutely triangular outline, and the shell is angulated at the internal groove, resulting in a distinctly angular, rhomboi­dal cross section. In Atrina the antero­ventral margin is sinuous, having a con­cavity at the byssal gape, and the shell is smoothly curved from dorsum to venter, resulting in a lanceolate cross section. ATRINA CAWCAWENSIS (Harris) Pl. 7, fig. 9, and text fig. 11 1919 Pinna cawcawensis HARRIS, G. D., Pelecy· poda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, p. 31, pl. 16, figs. 12, 13, and pl. 17, figs. 1, 2. [June 30] Origi,rud description.-General shape and size indicated by fig. I ; surf ace of the valves ~ith numerous radii above, well defined; below with concentric undulations upon which are super­ imposed even more radiating costae than above, but they are less distinct. Zigzag bases of fi.m­ briate folds upon the ribs precisely as in the living squamosissima Phil., or sem'inuda Lam. (pl. 16, figs. 12--13). . In outline this is like jacksoniana Dall, or argentea Con. The Claiborne sand, Jackson and Vicksburg specimens, however, so far as our specimens show, ha (j) c 0 l-~ LARGEST TRANSVERSE VALVE DIMENSION DIMENSION Left 55.l 32.2 (holotype) Left 54.2 35.8 54.1 25.5 51.4 24.6 49.5 26.7 47.1 24.6 47.0 33.8 43.8 26.0 43.7 21.5 42.5 26.8 42.3 21.4 42.1 21.8 37.5 23.8 35.6 20.9 34.6 21.1 34.4 18.3 32.1 16.8 31.5 18.0 28.5 14.8 25.0 15.5 Average 41.6 23.5 (left valves) or 56.5 percent of largest dimension Right 53.6 31.0 47.9 26.0 47.2 22.6 43.4 25.9 40.6 23.4 39.3 22.2 38.5 22.1 32.2 15.8 30.5 28.3 29.7 18.0 29.7 lS.8 29.4 16.5 29.1 15.9 22.3 14.4 Average 36.7 21.3 (right valves) or 58.0 percent of largest dimension Type data.--Holotype (left valve) and 42 paratypes (23 left and 19 right valves) are at the Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Excavation east of the intersection of South Liberty and East Planters streets, 3 blocks east and 3 blocks south of southeast corner of the court­house square, 0.4 mile air-line distance southeast of courthouse in the town of San Augustine, San Augustine County, Texas; Bur. Econ. Geology locality no. 202-T-8. Geologic horizon.-T y us member, Weches formation, Claiborne group, Middle Eocene. In zone of Cubitostrea lisbonensis (Harris) . · CUBITOSTREA (CUBITOSTREA) PETROPOLITANA Stenzel & Twining, n. sp. Pl. 11, figs. 5-12 1931 Ostrea sellaeformis Conrad var. I (part). RENICK, B. C., & STENZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. Description.-Shell small {largest di­mension to 35 mm) , thin ( thicknes.s of ­shell wall at mid·point of left valve about 1.5 mm), curved, broad, and semicircular to paddle-shaped; nearly all individuals without ·posterior auricle. Posterior end slightly produced and hroadly to very broadly rounded. Radial ribs of left valve bifurcate only along the obscure keel ; a few individuals have one or two short intercalated ribs near the antero-ventral margin. Ribs low, mostly broad, and evenly rounded in cross section. Interspaces evenly rounded con­cave and one-half as wide as the ribs in most individuals. Attachment area on nearly all individuals very large, occupy­ing from 1/3 to 5/6 of the valve; hence most left valves are somewhat distorted. Dimensions.-The following types were measured in millimeters (see fig. 13 for method of measurement) : LARGEST TRANSVERSE VALVE DIMENSION DIMENSION Left 32.1 19.7 28.0 19.6 29.6 18.5 33.5 26.3 22.2 12.8 Average 29.1 19.4 (left valves) or 66.7 percent of largest dimension Right 31.9 21.5 29.4 16.2 24.0 14.6 Average 28.4 17.4 (right valves) or 61.3 percent of largest dimension Type data.-Holotype (left valve) and 74 paratypes (26 left and 48 right valves) are at the Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.--Stone City Bluff. Geologic horizon.-Stone City ·beds, Claiborne group, Middle Eocene. For dis­ tribution in the individual beds of the Stone City section, see table 3. Remarks.-Four species comprise the subgenus Cubitostrea {Cubitostrea} in the Gulf Coastal Plain: perplicata (Dall) from the up·per Tallahatta of Alabama, sanctiaugustini Stenzel &Twining, n. sp., from the lower Weches of Texas, petro­politana Stenzel & Twining, n. sp., from the Stone City beds of Texas, and divari­cata (Lea) from the Cook Mountain for­mation of Alabama. Of these four species, C. (C.) perplicata (Dall) is distinguished by its nearly tri­angular outline and thick-walled shell; C. (C.) sanctiaugustini Stenzel & Twining has semicircular outline and broadly rounded posterior margin; C. (C.) petro­politana Stenzel & Twining is paddle­shaped and very broad; C. (C.) divaricata (Lea) is crescentically curved and is strongly 1produced and very narrow pos­teriorly. Gen118 CRASSOSTREA Sacco, 1897 Author.-Sacco, Federico (1897) I molluschi dei terreni terziarii del Pie­monte e della Liguria, pt. 23, p. 15. [June] Type species.-"C. virgi,niana (Gmel.)" = Ostrea virgi,nica Gmelin, 1791 = Crass­ostrea virginica (Gmelin). Type designation.--Original. First description of type species.­Gmelin, J. F. (1791) Caroli a Linne sys­tema naturae, etc., ed. 13, vol. 1, pt. 6, p. 3336. Type locality and horizon of type species.-Living on east and south coast of North America from Canada to Mexico. Generic description.-Shell large (to about 45 cm), outline highly variable but nevertheless mostly narrowly elongate to elongate-ovate, no auricles present on either valve. Fossil representatives show a short series of weak denticles on the mar­gins to either side of and just below the hinge' line; these denticles are not present in the type species and its living relatives. Left valve capacious, slightly to strongly convex, right valve nearly flat to slightly convex. Anterior and posterior margins straight to very broadly curved, ventral margin broadly rounded. Ligament area broadly to narrowly tri­angular, in some individuals much higher than long; consisting of a central, deeply excavate subarea, the resilifer, bordered on each side by a narrow, convex subarea in the left valve; a strongly convex resili­fer bordered on each side by a nearly flat subarea in the right valve. The single posterior adductor muscle imprint large, renif orm, shall ow, well defined, a pproxi­mately median between hinge line and ventral extremity of shell; the muscle im­print of living species has a purple color. Sculpture of left valve consisting of low, broadly rounded, poorly defined radial folds and concentric, imbricating growth lamellae, which are regularly spaced and have upturned margins in some species or are irregularly spaced and appressed in other species. Sculpture of right valve similar to that of left, except that radial folds are weaker or absent. Range of genus.-The exact range of Crassostrea is not yet known. Ostrea soleniscus Meek is a Crassostrea from the Woodbine group, Cenomanian, of Texas. The genus is represented today by the common Crassostrea virginica (Gmelin) of the east coast of North America, which is the type species of the genus. CRASSOSTREA FRIONIS (Harris) Pl. 12, ~s. 3-10 1919 Ostrea alabamiensis var. frionis HARRIS, G. D., Pelecypoda of the St. Maurice and Claiborne stages: Bull. Am. Paleontology, vol. 6, no. 31, p. 9, pl. 5, fig. 1. [June 30] 1931 Ostrea cf. alabamiensis Lea. RENICK, B. C., & STENZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas· Bull. 3101, p. 104. 1945 Ostrea /rionis Harris. GARDNER, JULIA, Mollusca of the Tertiary formatio-ns of no-nheastern Mexico: Geol. Soc. America Mem. 11, p. 82. Original descri ption.-Harris gave an extremely short description hy stating of this supposed "variety" of Ostrea ala­bamiensis Lea: "exteriorly . . . highly foliated (var. frionis pl. 5, fig. 1; •.." (Harris, 1919, p. 9). Revised description.-SheII large (to about 15 cm) , chiefly elongate-ovate, rarely narrowly elongate, built up of many well-defined laminae beginning at an early growth stage. Between the laminae are many hollow spaces, so-called chambers; many valves are somewhat crushed by compaction and their cham­bers have collapsed resulting in sunken and crushed portions visible in the in­terior of the valve. A series of small (10 to 12 per cm), regularly spaced denticles on the margins of the valves starts just below the hinge line and extends ventrally about one­fourth the distance to the ventral margin. On ·some individuals the denticles start well above the hinge line and continue ventrally to form a long series; this is the result of the cumulative effect of con­tinued growth and the preservation of previous growth stages. Sculpture of left valve consisting of low, broad, irregularly spaced radial folds, about 3 to 5 mm wide and 2 to 3 mm high, and fairly regularly spaced con­centric growth lamellae, which have free edges which turn away from the body of the valve. Sculpture of right valve similar to that of left except that the radial folds are very weak to absent. Remarks.-All individuals from the Stone City beds at Stone City are wave worn so that the beaks, valve margins, and most projecting edges of the lamellae are worn off smoothly. This condition ac­counts for the difference in appearance between the Stone City specimens and those from the general type area in south Texas, which have well-preserved lamellae and frilled edgeAS. (Compare PI. 12, figs. 3-10.) Dimensions.-The following specimens were measured in millimeters : LOCALITY VALVE HEIGHT LENGTH Stone City Bluff Left 148.0 est. 93.0 Left 117.0 63.0 .Right 86.8 38.8 'Riahtc 62.5 31.1 Atascosa County, Texas "On road below Pleasanton" (Bur. Econ. Geol. locality no. 7-T-l) Right Right ~ight 84.0 est. 71.0 66.0 40.0 46.0 53.0 Right 66.0 est. 40.0 Sabine County, Texas Rh?;ht bank of Sabine River (Bur. Econ. Geol. locality no. 201-T-5) Left 100.0 54.0 Right 80.0 est. 40.0 Harris' holotype (as measured from figure) Unknown 105.0 60.0 Average 89.7 50.8 or 56.6 percent of height Type data.-The holotype, according to Harris (1919., p. 206, explanation to fig. l, pl. 5), is ''Texas State Museum, No .. 1710."; however, the specimen cannot be located in Austin. Type locality.--"San Miguel Cr., S. E. corner of Frio Co . ., Tex., below De Viller's ranch" (Harris, 1919, p. 206, explanation to fig. 1, pl. 5). The type locality is unknown to us and its exact position geographically and stratigraphically remains to he found. The report on the geology of Frio County (Lonsdale, 1935) gives the best available information on the area but does not mention either the ranch or the fossil oyster. Geologic horizon.-The geologic ho­rizon of the holotype is unknown; it is either the Stone City beds or the Cook Mountain formation. We know this species occurs definitely in the Stone City beds at Stone City Bluff and on the Texas side of the Sabine River (Bur. Econ. Geology locality no. 201-T-5). We have not seen it at any exposures definitely identified as Cook Mountain. Locality 201-T-5 is in Sabine County, Texas, on the right bank of Sabine River near the center of the long west-east reach of Harper's Bend opposite section 36, T. 5 N., R. 13 W. of Sabine Parish, Louisiana, 0.30 mile northeast of Crane Pond and 1.0 mile air-line distance northwest from U. S. Geological Survey bench mark 164 at the road fork known as Columbus Loui­ ' siana. This is locality 23 of Veatch, ( 1902, p. 130, pl. 33) ; compare also Negreet quadrangle, 1/62,500, U. S. Geol. Survey, 1944. The material was collected by C. L. Baker, Rio B:cavo Oil Company Col­lection. Remarks.-Many of the fossil oysters described from the Gulf Coastal Plain probably belong to the genus Crassostrea, but most have not been sufficiently studied and are in need of revision. The following species represent only a small part of the group. Crassostrea alabamiensis (Lea) (1833, p. 91, pl. 3, fig. 71) from the Gosport sand, Claiborne group, Middle Eocene, of Claiborne Bluff, Monroe County, Ala­bama, is relatively small, fragile, and thin shelled, has very thin laminae, which are fewer in number and show only slight reg­ularity of spacing, and lacks radial folds on either valve, but it has low, narrow rounded radial threads on the early growth stages of the shell ; the threads in­crease in number by intercalation and bi­furcation and are visible only on undecor­ticated shells. Crassostrea amichel (Gardner) ( 1945, pp. 81-82, pl. 3, figs. l, 2) from 1.5 miles north of the crossing of U. S. Highway 81 (Laredo-Cotulla road) over Dolores Creek or 28 miles north of Laredo, Webb County, Texas, is large, thick shelled, and has many fairly regularly spaced la­minae; the edges of the growth lamellae are not frilled, and radial folds are lack­ing on both valves. The exact geologic horizon of Crassos­trea amichel (Gardner) is not known, be­cause the Yegua-Cook Mountain boundary in southwestern Texas has not yet been definitely traced from the type area of the Yegua in central Texas. If the interpreta­tion of Lonsdale & Day (1937) is fol­lowed, the oyster locality falls into the Cook Mountain formation, but if the in­terpretation of Patterson (1942) is u~ed, it is probably in the "La Perla oyster shal~'' of the basal Yegua formation. Crassostrea gigantissima (Finch) (1824, p. 40) [=Ostrea georgiana Con­rad, 1834, p. 156; compare Howe, 1937) from the Jackson group, Upper Eocene, of Shell Bluff, Burke County, Georgia, is very large (to at least 20 inches) , thick shelled, very narrowly elongate, and straight except for curved umbones, and has many closely spaced growth lamellae, but lacks radial folds on either valve. Superfami1y ANOMIICAE Family ANOMIIDAE Genus ANO MIA Linne, 1758 Author.-Linn~, Carl (1758) Systema naturae, etc., ed. l 0, vol. I, pp. 700-703. Type species.-"Anomia ephippium" = Anomia ephippium Linne. T y p e designation.-Subsequent by Schmidt, F. C. (1818) Versuch iiber die beste Einrichtung, etc., Gotha, Justus Per­thes, pp. 71, 177, ] 95. First description of type species.­ Linne (1758, p. 701). Compare Dodge (1952,pp.198-200). Type locality and horizon of type spe­ cies.-Living off Europe from Iceland and the Shetland Islands to the north coast of Africa and throughout the Mediterranean. Generic description.-Shell translu­cent, to 50 mm long, thin, subcircular or oblong, irregular, adherent and conform­ing to substratum, highly inequivalve. Left valve nacreous, larger and convex; right valve thinner, smaller, flat or con­cave, near umbo deeply emarginate to provide a circular or vertically oblong byssal f oramen. Animal attached to sub· stratum; the right valve is next to sub­stratum and the left valve is cupped over the right. Two pedal retractor muscles and a byssal muscle extend from their at­tachment on left valve to the foot and the root of the calcified byssus which passes through the for amen of the right valve. Byssus a thick, short cylindrical, calcified plug free from the edge of foramen but grown onto substratum. Hinge short, edentulous; an internal resilium attached to umbonal cavity of left valve and to chondrophore on pos­tero-dorsal side of for amen on right valve. Hinge margin of left valve incurved and thickened. Left valve has a subcentral group of 4 muscle imprints: the most ven­trally placed one is that of the adductor; obliquely next to it, toward dorsum and anterior, is that of the posterior pedal re­tractor; next to the hinge is the combined imprint of the anterior pedal retractor and the byssal n1uscle. Right valve has only the adductor muscle imprint ventral of the f oramen (compare detailed descrip­tion of anatomy given by Jackson, 1890, pp. 354-362) . Pallial line simple. Sculpture ribbed, pustulate, or concen­trically lamellar. Range of genus.-Zittel (1881/85, vol. 2, p. 22) stated that the oldest species is found in the Liassic. The genus is cosmo­politan today from low-water mark to about 100 fathoms. ANOMIA EPHIPPIOIDES Gabb Pl. 8, figs. 3, 6, 7, 9-12; Pl. 9, figs. 1, 2 ; Pl. 11, fig. 7; and text figs. 14, 15 1860 Anomia ephippioides GABB, W. M., De­scriptions of new species of American Tertiary and Cretaceous fossils: Acad. Nat. Sci. Philadelphia J our., 2d ser., vol. 4, pt. 4, p. 388, pl. 67, fig. 59. [December 11] 1865 Anomia ephippioides Gabb. CONRAD, T. A., Catalogue of the Eocene and Oligocene Testacea of the United States: Am. Jour. Conchology, vol. 1, no. 1, p. 15. 1898 Anomia ephippioides Gabb. DALL, W. H., Contributions to the Tertiary fauna of Florida, etc.: Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 782. 1914 Anomia ephippioides Gabb. DEUSSEN, ALEXANDER, Geology and underground waters of the southeastern part of the Texas Coastal Plain: U. S. Geol. Survey Water­Supply Paper 335, p. 59, pl. 5, figs. 2, 2a. 1919 Anomia ephi,ppioides Gabb. HARRIS, G. D., Pelecypoda of the St. Maurice and Clai­borne stages: Bull. Am. Paleontology, vol. 6, no. 31, p. 16, pl. 11, fiV-s. 1-3. 1923 Anomia ephippoides Gabb. TROWBRIDGE, · A. C., A geologic reconnaissance in· the Gulf Coastal Plain of Texas near the Rio Grande: U. S. Geol. Survey Prof. Paper 131-D, p. 95. [error for ephippioides] 1924 Anomia ephippoides Gabb. DEUSSEN, ALEX­ANDER, Geology of the Coastal Plain of Texas west of Brazos River: U. S. Geol. Survey Prof. Paper 126, p. 67, pl. 22, figs. 6, 6a. [error for ephippioides] 1931 Anomia ephippoides Gabb. RENICK, B. C., & STENZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104. [error for ephippioides] 1932 Anomia epippoides Gabb. TROWBRIDGE, A. C., Tertiary and Quaternary geolo'~ of the lower Rio Grande region, Texas: U. S, Geol. Survey Bull. 837, pl.·43, fig. 2. [error for ephippioides] 1945 Anomia ephippioides Gabb. GARDNER, JULIA, Mollusca of the Tertiary formations of northeastern Mexico: Geol. Soc. America Mem. 11, pp. 73-74, pl. 1, fi6s. 16, 18. Origi,nal description.-Very irregularly sub· quadrate, sometimes nearly circular, sometimes almost triangular; convex, occasionally marked by longitudinal rugae, and always by distinct lines of p:rowth; lower valve, the muscular for· amen large; ligament margin thickened. Size of largest specimen.-Length 1.5 in., width 1.3 in. Common. ('Gabb, 1860b, p. 388.] Revised description.-Shell irregular, subcircular, to 45 mm long. Sculpture consisting of distinct lamel­lar growth lines and many pustules on both valves. On young shells the pustules are minute; older shells have coarser pus­tules, which are either round or slightly radially elongate, producing a stubbly ef · feet. Many, though not all, left valves have a superimposed allomorphic sculp­ture, inherited from their substrata, con­sisting of subparallel, slightly divergent, flat-topped ribs separated by narrower in­terspaces, which are di:fferentl y oriented on different individuals (figs. 14 and 15). Al lomorphic sculpture Shell of Venericordlo (Venericor) p/orJlcosla densola (Conrad) Growing margin Fie. 14. Diagram showing how allomorphic sculpture is acquired by an Anomia growing on a, Vencricardia substratum, x2.9 natural size. Fie. 15. A young Anomia ephippioides Gabb with allomorphic sculpture growing attached to Yenericardia (Yenericor) planicosta densata (Conrad) ; a reconstruction, xl.75 natural size. Byssal foramen large {height is 18 to 30 percent of height of valve; length is 13 tQ 23 percent of length of valve) , cir­cular or oblong, generally conforming to outline of valve~ in some individuals shut off dorsally by the overlapping of the two horns of the valve, with the horn bearing the chondrophore proximal and the other distal. Byssus plug a very low small cone; the larger base elongate and oval in outline; the small top flat, pyriform, slanting down toward its narrower end; the slopes ris­ing gently from the base but very steep or slightly overhanging at top; grown onto various other shells by its base. Top surface of byssus plug is densely striate. Dimensions.-The following topotypes were measured in millimeters: LENGTH HEIGHT OF OF FORA-FORA­ LENGTR HEIGHT WIDTH MEN MEN Double valves 43.0 36.5 14.5 5.5 12.8 33.7 31.7 9.7 5.9 6.0 33.4 30.6 7.7 7.7 6.1 Single left valve (the largest valve at hand) 41.4 45.7 est. 8.7 __ _ Gabb's figured type, a left valve measured by Stenzel in 1948 ' 20.l 24.2 All the byssal plugs of Anomia ephip­pioides Gabb found were measured a to­ ' tal of 94. Most of these were from bed (s) of the ~tone City section. The largest plug found is attached to the inside surface of a fragment of the shell of a nautiloid ' probably Aturia {Brazaturia} brazoensis Stenzel; it measures 8.4 mm long, 5.0 mm wide, and 1.4 mm high from surface of sub~tratum to top of plug (Pl. 8, fig. 7) . The highest plug found is attached to the outside surface of a left valve of Crassos­trea Jrionis (Harris) ; it measures 6.1 mm long, 5.0 mm wide, and 2.0 mm high. Average ~ize of 56 plugs is 4.5 mm long, 2.9 mm wide, and 0.6 mm high. Remarks.-Left valves are much more common than right valves. This is gener­al~y true of fossil Tertiary species of Arw­mia, because the right valve is thinner and more fragile than the left. Of the 584 valve.s collected, 578 or 99 percent are left valves. The diagnostic specific feature is the pustules, not shown by the smooth A. lisbonensis Aldrich from the Cook Moun­tain formation. The ribbed allomorphic sculpture, copied from the substratum on which the animal grew, is characteristic although not diagnostic (text figs. 14 and 15 and Pl. 8, figs, 6 and 9) . Of the 578 left valyes collected, 154 or 27 percent have this sculpture; the others either do not have it or were attached to smooth substrata, hence have a smooth allomor­phic sculpture hardly recognizable as such. The ribbed allomorphic sculpture is clearly derived from a substratum that had flat-topped, slightly divergent ribs with narrower interspaces, and that sub­stratum can have been only Venericardia (Venericor) planicosta densata (Conrad) which is a common associate of Anomi~ ephippioides Gabb at Stone City Bluff and on which we have found byssal plugs pre­served. However, no Anomia has been found directly in contact with or still at­tached to this Venericardia, but neither has it been found still attached to any other shell. Byssal plugs have been found attached to many shells. The following table sum­marizes the data. NUMBER ATTACHED TO PLACEMENT 0.F ~LUGS Anomia ephippioides Gabb outside of 32 left valves 39 inside of I left valve · 1 on right valves 0 Aturia (Bra:aturia) brazoensis Stenzel (?) inside of 1 shell 2 Barbatia ( Barbatia) uxorispa/,meri Stenzel & Krause outside of 4 left valves 4 outside of 1 right valve 1 inside of valves 0 Callocardia fragment inside of 1 right valve 2 outside of same right valve 1 ?C erithium outside of 1 shell 2 Cubitostrea petropolitana Stenzel &Twining inside of 2 left valves 2 Crassostrea frionis (Harris) outside of 3 left valves 15 outside of 3 right valves 6 inside of same right valves 5 outside of 4 fragments 4 inside of 1 fragment 1 V enericardia (Venericor) planicosta densata (Conrad) out1;:ide of I left valve 1 inside of I left valve 1 outside of 2 ri~ht valves 2 inside of 1 right valve I The fact that almost all the plugs found attached to an Anornia ephippioides Gabb are on the convex outsides of left valves indicates that the plugs and the animals making the plugs were probably attached while the substratum was alive. It is sim­ilar with the attachment of plvgs to the valves of Barba!ia ( Barbatia) uxoris pal,­meri Stenzel & Krause, n. sp. The oysters, however, have many byssal plugs attached to both the inside and outside surfaces of the valves. The oyster valves are also well worn. It must be concluded, therefore, that the oysters 'vere dead at the time the individuals of Anomia attached them­selves. The nautiloid certainly is a frag­ment of a shell, and the breaks delimit­ing the fragment are naturally worn and not accidental recent breaks. This frag­ment probably rested with the convex side down on the sediment at the bottom of the water. The genus Arwmia is fairly well repre­sented in the Gulf and Atlantic Coastal Plain Eocene and Paleocene as is shown by the species discussed below. Anomia ru/a Barry (Barry &Le Blanc, 1942, pp. 55-56, pl. 3, fig. 9; pl. 6, figs. 1, 2) from the Ilall Summit formation, upper Midway group, Paleocene,-of a road cut in the center of section 12, T. 8 N., R. 14 W., about 6 miles southwest of z,volle, Sabine Parish, Louisiana, resem­bles A. lisbonensis Aldrich except that it is smaller, more regular, and has more pointed umbones. Anomia malinchae Gardner (1945, p. 72, pl. 5, figs. 1, 2) from the lower part of the Wilcox group of the vicinity of Cerralvo, Nuevo Leon, Mexico, is large, smooth, and nearlv. circular. Aldrich ( 1898, p. 97; 1903, p. 99, pl. 4, figs. 13, 14) described a long narrow rhell from the Bashi marl member, Hatchetig­bee formation, ~7ilcox group, Lower Eo­cene, of Wood's Bluff, Alabama, as Ano­mia navicelloides. The shell is conical, and the beak is not marginal. Anomia sellardsi Stenzel in Renick & Stenzel (1931, p. 90, pl. 6, figs. 3, 4) re­mains a nomen nudum but indicates the presence of the genus in th~ Weches for­mation. From the. Woodstock member of the Nanjemoy formation of Pope's Creek, Charles County, Maryland, an Anomia marylandica W. B. Clark & G. C. Martin (190la and b, pp. 79, 187, pl. 41, figs. 2, 2a, 3) has been described; its surface is marked by fine raised radiating threads. On the other hand, Anomia mcgeei W. B. Clark (1895, p. 5) seems to be highly questionable; compare Clark & Martin (190lb,pp.187-188). Anomia hammetti Harris (1919, p. 18, pl. 11, fig3. 4, 5; pl. 12, figs. 1, 2) from the Cook Mountain formation, Claiborne group, Middle Eocene, of Hammett's Branch, Bienville Parish, Louisiana, is vertically oblong, finely costate, and dif­fers from A. ephippioides Gabb in having a heavy shell, a more regular oval outline, and continuous radial costae rather than irregular pustules. Anomia l~sbonensis Aldrich (1886, p. 41, pl. 4, fig~ 6) from the Cook Mountain formation of Lisbon Bluff and Claiborne Bluff, Monroe County, Alabama, is larger than A. ephippioides Gabb, has rather full umbones, and is devoid of pustules. It is widely distributed in the Cook Mountain formation of the Gulf Coastal Plain. Conrad (1843, p. 310; 1846a, p. 22, pl. 1, apparently fig. 15, not fig. 14 as stated in text) described Anomia jitgosa, from the "white limestone of S. Carolina.'' This species has been listed from the Cooper marl by Tuomey (1848, pp. 163, 166, 167) and Cooke (1936, p. 85). Cooke & MacNeil (1952, p. 27) questionably place the Cooper marl in the Lower Oligo· cene. The A. jugosa Conrad differs from A. ephippioides Gabb in having broad, rounded, irregular, widely spaced, scale­bearing radial ribs. The type specimen has been refigured by us on Plate 8, figure 8. Type data.-There are 9 syntype valves in the Philadelphia collection; of these only two have the ribbed allomorphic sculpture, and one of these, with some imagination, can be matched with Gabb's type figure. The figured type, height 24.2 mm, length 20.1 mm, is cracked and de­formed. There are two ink labels in Gabb's handwriting: "Anomia ephi ppioides / Gabb / Dupl. types / Eocene / Texas / Smiths'n Inst." and "Specime / figured I Anomia ephippioides Gabb. / Types / Jour. Acad. 2, s. v. 4, pl. 67, £. 59 / Eocene / Wheelock / Texas / W. M. G." (Stenzel notes, 1948). Number 2719 Academy of Natural Sciences of Phila­delphia, Philadelphia, Pennsylvania. Type locality.--Presumably Stone City Bluff. Geologic horizon.-The species is com· mon in and restricted to the Stone City beds, for which it is a diagnostic guide fossil. At Stone City Bluff it is particular­ly abundant in bed ( s) . In the Cook Mountain formation Anomia lisbonensis is equally as conunon. Class EULAMELLIBRANCHIA Order HETERODONTIDA Suborder LUCININA Superfamily CARDITICAE Family CARDITIDAE Genus VENERICARDIA Lamarck, 1801 Author.--Lamarck, J. B. (1801) Sy­steme des animaux sans vertebres, etc., ed. 1, Paris, p. 123. Type species.-"Venus imbricata" = Venus imbricata Gmelin, 1791 = Veneri­cardia imbricata (Gmelin). T y p e designation.-Subsequent by Schmidt, F. C. (1818) Versuch iiber die beste Einrichtung, etc., Gotha, Justus Per­thes, pp. 57, 176. First description of type species.­Gmelin, J. F. (1791) Caroli a Linne Sys· tema Naturae per regna tria naturae, etc., ed. 13, vol. 1, pt. 6, p. 3277. Type locality and horizon of type spe· cies.-"Habitat in Campania Gallorum" ( Gmelin, 1791, p. 3277) ; "fossile de Courtagnon et de Grignon" (Lamarck, 1801, p. 123) ; Grignon, west of Paris, Departement de Seine et Oise, France; from the Calcaire grossier, Middle Eo­cene. Generic description.-Shell nonbyssiferous, closed, rounded, trigonal, or cordate. Umbones anterior, prosogyrate. Lunule small hut deep. Escutcheon narrow and elongate. Sculpture dominantly radial. Ligament external, opistho­detic, parivincular. Hin~e dentition in the right valve consisting of three oblique cardinals; in the left valve of two: laterals of both valves absent or very feeble. Muscle impressions strongly de­fined. Pallial line entire. Inner margins crenate. [Gardner, 1945, p. 92.] A more detailed description and dis­cussion are given by Gardner & Bowles {1939,pp.167-168). Subgenus VENERICOR Stewart, 1930 Author.-Stewart, R. B. (1930) Gabb's California Cretaceous and Tertiary type lamellibranchs: Acad. Nat. Sci. Philadel­phia Special Pub. 3, pp. 153-158. [Au­gust 9] Bureau of Economic Geology, The University of Texas Type species.-"Venericardia planicos­ta Lamarck" == f'enericardia (Venericor) planicosta Lamarck. Refigured by us from topotype material; see text figure 16. Type designation.-Original, Stewart, ( 1930, p. 153). First description of type species.­Lamarck, J. B. (1801) Systeme des ani­maux sans vertebres, etc., ed. 1, Paris, p. 123. Type locality and horizon of type spe­ cies.-"Fossile des env. de Paris" (La­marck, 1801, p. 123) ; Paris Basin, France; from the Calcaire grossier, Middle Eo­ cene. sists of about 17 to 39 radial ribs, which begin narrow, sharply crested, and finely nodulated, but grow into simple and flat­topped ribs, separated by slightly nar­rower ·u-shaped channels; overrun by the incrementals toward the margins. A m.ore detailed description and dis­cussion are found in Gardner & Bowles (1939, p. 168). Range of subgenus.-In North Amer­ica, where it is well developed, the sub­genus is found from the lowermost part of the local Paleocene to the end of the upper Eocene inclusive. In Europe the subgenus occurs at the type locality of FIG. 16. Hinge features of V enericardia (Venericor) planicosta planicosta Lamarck, 1801, from the Calcaire grossier, Lutetian, of Grignon, Departement Seine et Oise, France; xO.75 natural size. Topotypes of the type species of Venericor Stewart, 1930. Subgeneric description.-Shell large, to 117 mm long, heavy, trigonocordate. Umbones inflated. Anterior end short, ob­liquely rounded. Posterior lateral margin obscurely truncate. Lunule narrow and deep. Ligament deeply inset, marginal, mount­ed .on heavy nymphs. Hinge plate high, trigonal. Three cardinal teeth in the right valve, two in the left (fig. 16). Pallial line rather far removed from the crenate inner margins. Sculpture con-the Montian (V. (V.) duponti Cossmann) and is represented in the succeeding Eo­cene beds to the Auversian of the Paris Basin, but it is absent in the overlying Bartonian. Apparently it survived a little longer in North America than in western Europe. Rutsch (1936a, pp. 154-156) mentions two possible supposedly Upper Creta­ceous forerunners of the subgenus, V. weg· eneri Rutsch from the Plateau of Tenidah in the Libyan desert 4nd V. baronneti Munier-Chalmas from Tunisia. We are not sufficiently familiar with the two fossils involved, their type localities, and the stratigraphic succession and correlation at these places to venture a criticism hut regard the stratigraphic position of V. wegeneri Rutsch, which is based on very · early pioneering work in North Africa, much too insecure. VENERICARDIA (VENERICOR) PLANICOSTA DENSATA (Conrad) Pl. 8, fig. 10, and Pl. 11, figs. 1-4, 13, 14 1845 Cardita densata CONRAD, T. A., Descriptions of eight new fossil shells of the United States: Acad. Nat. Sci. Philadelphia Proc., vol. 2, p. 173. [February] 1867 Yenericardia Mooreana CONRAD, T. A., Notes on fossil shells and descriptions of new species: Am. J our. Conchology, vol. 3, p. 190. [September 5] 1939 Y enericardi.a (Venericor) densata Conrad. GARDNER, JULIA, & BOWLES, EoGAR, The Yenericardi,a planicosta group in the Gulf Province: U. S. Geol. Survey Prof. Paper 189-F, pp. 189-192, pl. 37, fig. 7; pl. 45, figs. 1-11, 14. 1945 Y enericardi,a (Yenericor) densata Conrad. GARDNER, JULIA, Mollusca of the Tertiary formations of northeastern Mexico: Geol. Soc. America Mem. 11, p. 36. 1946 Yenericardia ptanicosta, var. densata Con­rad. HARRIS, G. D., The Mollusca of the Jackson Eocene of the Mississippi embay­ment (Sabine River to the Alabama River) ; pt. 1, Bivalves: Bull. Am. Paleon­tology, vol. 30, no. 117, pp. 65-66. Origin:al. description. -Obliquely cordate, ventricose, thick, with about twenty-five flattened costae, obsolete towards the base, narrow, pro­found, elevated and crenulated on the umbo; umbo very prominent at the apex; anterior basal margin obliquely subtruncated; posterior ex­tremity truncated, direct; cardinal area very thick and dilated, the teeth oblique. Height 1 5/8 inch. Length the same. Locality.-Claibome, Alabama. This pretty species abounds in entire speci­mens in the argillaceous stratum near low water mark in the Claiborne Bluff. I found none in the upper beds. Compared with C. planicosta, it is much smaller, comparatively shorter, thicker, and may always be readily distinguished by the crenulated ribs on the umbo. [Conrad, 1845, p. 173.] . The following is the original descrip­tion of Venerkardia mooreana Conrad: Description.~ordate, thick, ventricose; ribs 27 or 28, flattened on the back, prominent, square, broader on the back than beneath, or the interstices are narrowed at the surface by a slight lateral carination of the ribs; ribs prominent to the ventral margin; narrow, close and prominent on the anterior and posterior slopes ; crenulated on the beak and umbo. Length 1 % inch. Loca/,ity.-Texas. Dr. Francis Moore. Eocene. Distinguished from planicosta and densata by its size, by the prominence of the ribs on the margin of the valves, and on the anterior and posterior slopes, and by the interior marginal teeth which are not carinated on the margins. [Conrad, 1867b, p. 190.] Dimensions.-T he following valves from Stone City Bluff were measured in millimeters: WIDTH BED VALVE LENGTH HEIGHT OF VALVE (x) Right 22.0 21.0 est. 8.0 Right 15.8 14.8 5.2 Left 12.7 12.5 4.5 Left 10.3 10.0 3.4 Right 9.6 9.7 3.3 (w) Right 37.0 35.6 12.9 . Left 19.3 18.8 7.4 Right 18.4 17.8 7 .0 Right 16.4 15.3 5.8 (u) Right 38.6 36.7 13.7 Right 35.7 36.1 11.8 Left 30.0 30.0 11.4 Right 28.5 29.8 11.7 Right 26.9 27.2 10.0 Left 26.4 25.1 10.2 Right 25.6 25.4 9.6 Right 25.0 23.5 9.0 Left 19.0 18.5 8.2 Left 13.7 13.4 5.0 Right 8.0 8.1 4.9 (s) Right 35.1 33.5 est. 12.1 Right 28.5 26.8 10.5 Left 25.1 24.3 10.0 Left 22.l 22.1 8.4 Left 19.6 18.8 7.6 Right 19.0 18.0 7.4 Left 18.3 17.4 7.2 Left 17.9 17.4 7.0 Right 16.8 16.8 6.0 Left 16.8 16.2 5.8 Right 16.6 16.1 5.8 Right 15.8 15.3 5.9 Ri~ht 15.5 15.2 5.9 Right 14.1 14.1 4.6 Right 14.0 13.8 5.3 Left l;l.1 12.8 4.7 Left 13.0 12.7 4.8 ( r) Left 26.0 est. 25.3 10.0 (d) Left 7.1 7.4 2.5 Average 20.3 19.8 6.5 Conrad's holotvpe of Ven.ericardia mooreana measured by Sten7.el in 1948 Left 24.5 22.4 9.1 Remarks.-The species is fully de­scribed by Gardner & Bowles (1939, pp. 189-192) who also give a complete syn­onymy to 1939. Although we are following Gardner & Bowles in combining V. mooreana Con­rad with V. densata (Conrad), we seri­ously doubt that these two ought to be combined as there are obvious and con­stant differences between them. These dif­ferences are no less significant than those between other subspecies of Venericardia (Venericor) planicosta Lamarck. Type da/n,.-The types of Cardita den­sata Conrad are presumably at the Acad­emy of Natural Sciences of Philadelphia, Philadelphia, Pennsylvania. The types of Venericard'ia mooreana Conrad, catalog no. 13243, are at the Academy of Natural Sciences of Philadel­phia. The entry hook of the Academy states as follows: "Venericardia moore­ana Conrad/ Wheelock? /Texas/ T. A. Conrad donor, holotype and paratype." The card label in Angelo Heilprin's hand­writing states: "Cardita Mooreana.. Con. / = C. planicosta, De Blainv. / Texas." The types consist of 2 left valves, one of which is broken; both have written on them on their inside in Conrad's hand­writing: "Mooreana / Texas." They ap­pear to have been collected at Stone City Bluff. [Notes made by Stenzel, 1948.] Type loca/,ity.-The type locality of V. (V.) planicosta densata (Conrad) is base of bluff at Claiborne, on left bank of the Alabama River, T. 7 N., R. 5 E., west­central Monroe County, Alabama. Cook Mountain (or Upper Lisbon) formation, Claiborne group, Middle Eocene. Geologic horizon.-T he Venericardia from Stone City Bluff is very similar to that from the Weches formation of Texas and both are included in V. (V.) plani­costa densata (Conrad), following Gard­ner &Bowles. In the same area, the Cook Mountain formation, which overlies the Stone City beds, contains a distinctly dif­ . f erent form, referred by Gardner &Bowles to V. (V.) claiboplata Gardner & Bowles. Subgenus CLAIBORNICARDIA SteDMI A Krause, a. sahgen. Authors.-Stenzel, H. B., & Krause, E. Type species.--Cardita a/,ticosta/4 Con­rad, 1833 = Venericardia (Claibornicar­dia) al,ticostat,a (Conrad) • Refigured by us from to potype material on Plate 13, fig­ures 1-9; Plate 14, figure 5; and text figure 17. Type designation.-Herewith, that is, original. First description of 'y p e species.­Conrad, T. A. (1333a) On some new fos­sil and recent shells of the United States: Am. Jour. Sci., ser. 1, vol. 23, p. 342. Type locality and horizon of type spe­ cies.--Claiborne Bluff on left hank of the Alabama River, T. 7 N., R. 5 E., west­central Monroe County, Alabama. Gos­port sand, Claiborne group, ~iddle Eo­cene. Subgeneric descripiion.-Shell wall medium to thick; shell to about 70 mm long, tending to elo·ngate outlines (height is 73 to 100 percent of length),· trapezoi­ dal to suhrectangular to suhovate, strong­ 1y inflat~ (width of valve is 34 to 50 per­ cent of height). Umhones anterior (at 0.11 to 0.34 of length of valve)-, tumid, prosogyrate. Anterior end short and rounded. Posterior end truncate and in some species produced; hence the poste­rior margin is either almost vertical or inclined postero-ventrally. ·Ventral mar­gin convex to gently convex to nearly straight. Lunule very small (about 1.0 to 3.5 mm wide·and 1.7 to 2.5 mm long), convex, slightly wider in the right valve than in the left, deeply inserted between umbones and antero-dorsal margins; the anterior end of the lunule is sunk in to form a narrow cleft in front of the hinge teeth; the posterior end is covered up by the umbo. Escutcheon very long and nar­row (up to 3mm). Hinge of right valve consists of three teeth: a minute thin oblique anterior car­dinal tooth (3a) rising from the anterior margin of the anterior one {2') of the two sockets, present as a rudiment in some species hut absent in others; a long, nar­row, curved median cardinal tooth {3b); K,. in Stenzel, H. B., Krause, E. K., & · and a very long and thin; curved posterior Twining, J. T. (1956). cardinal tooth (Sh) fused to the posterior ____.------/igoment; --./unule 4b Fie. 17. ·Hinge features of V enericardia ( C lai,bormcardia) alticostata (Conrad) , 1833, from the Gosport sand, Claiborne group, Middle Eocene, of Claiborne Bluff, Monroe County, Alabama; xl.5 natural size. Topotypes of the type species of Claibornicardia Stenzel & Krause, n. subgen. nymph. Hinge of left valve consists of two cardinal teeth: a short, heavy, triangular or transversely elongate anterior cardinal tooth (2), and a long, slender, curved pos­ terior cardinal tooth ( 4b) , the anterior tip of which touches the posterior end of the lunule from below. Immediately ventral to the cleft made by the anterior margin of the lunule in the left valve is a small raised area that may he regarded as an obscure anterior lateral tooth and fits into a slight depre.ssion in the right valve. Ligament groove rather long (about 40 to 50 percent of length of valve) , curved, opisthodetic, deeply inset. Adductor mus­ cle imprints large; the anterior one sub­ elliptical, the posterior one rounded-pen­ tagonal. Anterior pedal retractor muscle imprint small, situated between the an­ terior adductor muscle imprint and the cleft of the lunule. Posterior retractor muscle imprint j9ined to the posterior adductor muscle imprint and fonning a tail-like dorsal extension to the latter. Pal­ lial line simple. Inner margin crenate in harmony with the costae. Sculpture consists of 25 to 32 com­ pound costae. T h e anterior compound costae are clearly tripartite, and each con­sists of a large dominant median rib, rounded and nodulated on top, surmount­ing a rounded and nodulated lower later­al. rib on either side. In some species the lower lateral ribs are overhanging so that the interspaces between the compound costae are narrow and cleft-like, but in others the interspaces are about one-half the width of the compound costae. To­ward the umbonal ridge the lateral ribs on either side of the compound costae become smaller or even obsolesce to form a large triangular base, from the center of which rises the narrow dominant me­dian rib; here the inters.paces have broad V-shaped or U-shaped channels. The post­umhonal slope has 8 to 9 simplified costae of sharp triangular cross section; the fourth one from the posterodorsal margin is higher than the others. Range of subgenus.-All th e known species of Claibornicardia are from the Weches, Stone City, Cook Mountain, and Gosport formations of the Claiborne group, Middle Eocene, and the Calcaire grossier, Middle Eocene, of France. Venericardia hesperia Gardner from the Midway group, Paleocene, of Texas (Gardner, 1923, pp. 112-113, pl. 32, figs. 1, 2; and Trowbridge, 1932, pl. 31, figs. 1, 2) has been regarded by Gardner & Bowles ( 1939, p. 195, pl. 46, figs. 4, 5) as "undoubtedly much more closely al­lied with the V. alticostata group . . . it seems to be related to the earlier members of the planicosta group." Indeed, Vener­icardia hesperia Gardner is very closely related to V. rtheastern Mexico: Geol. Soc. America Mem. 11, p. 106 . Original description.-Wide, flattened, nearly equilateral; beaks small, inclined internally; hinge line in advance of the beaks, straight, posterior slightly curved: surface smooth, or covered only by obsolete lines of fY'rowth. Dimensions.-Length .5 in., width .9 in., thick­ness .2 in. LocaUty.-Caldwcll Co. 0TlP. specimen, in my collection. [ Gahb, 1860h, p. 337.] Revised description.-Shell thin a n d fragile, to about 35 mm long, elongately ovate (height is about 58 percent of the greatest length) , compressed (width is about 13 percent of height). Umbones very slightly posterior (at about 0.53 of greatest length of valve) ; umbones and dorsal margins form an obtuse angle of about 135 degrees. Anterior end well rounded. Posterior end becomes progres­sively more acuminate during the growth of the shell; at about 33 mm length the posterior end is a rounded angle of 123 degrees; ·a second rounded angle of 164 degrees is located on the postero-dorsal margin 2 mm from the posterior extrem­ity; a third rounded very obtuse angle develops where the postero-dorsal mar­gin begins to fold over inward. Ventral margin broadly rounded, tending to be­come straight slightly posterior of its middle; the emargination at its posterior end is short and hardly noticeable. Sig­moid fold of valve commissure very slight; posterior tip of left valve turns inward slightly. At a length of 33 mm of the shell, the anterior lateral hinge tooth is 4.5 mm from the umbo and the posterior lateral tooth is 8.8 mm from the umho. In the left valve the anterior lateral tooth is elon­gate, triangular, and compressed; the posterior lateral tooth is slightly heavier than the anterior one. Pallial line and muscle imprints obscure. The pallial si­nus appears to approach the posterior adductor muscle imprint by one milli­meter. Rostrum not defined by any ridge, showing merely by the change in direc­tion of the growth lines. Surface of valve essentially smooth and glossy. Sculpture consists of very fine, fairly regular, sharp­ly impressed concentric lines, about 6.2 per millimeter, restricted to the anterior two-thirds of the valve; toward the pos­terior these impressed lines fade out rath­er quickly, and the posterior one-third of the valve is free of them; glossy smooth growth wrinkles occupy the region be­tween the fade-out of the impressed lines and the rostral area; the rostral area has crowded, sharply defined growth lines. Dimensions.-The monotype and th e following topotypes were measured in mil­limeters: HEIGHT VERTICAL TO GREATEST GREATEST WIDTH BED VALVE LENGTH LENGTH OF VALVE Monotype; measured by Stenzel Double 18.7 12.7 5.45 (both) (w) Left 18.4 11.2 2.3 (u) Right 16.7 10.0 2.2 (s) Left 32.3 18.8 est. 2.4 est. (p) Right 13.0 8.2 est. 1.4 Average 19.8 12.2 2.2 Remarks.-Length and width seem to he transposed in Gabb's original descrip­tion. Gabb's monotype, preserved in Phil­adelphia, is a double-valved individual fille.d with rust-brown clay-ironstone, hut it has the posterior end missing as is also shown on Gabb's original figure of the monotype. When seen from the dorsum it shows a slightly bent J>QSterior end, which is so characteristic of the Tellinidae. The disk is smooth and porcelaneous, but to· ward the margin there are thin, impressed concentric lines. The hinges of these shells are rarely recovered so fragile is the shell. Most ma­terial collected falls apart along numer­ous hair-line cracks and defies reassembly. The preservation of Gahb's monotype is unique; it has kept the shell very effec­tively from falling to pieces. Dall (1890/1903, p. 1015) united Tel­lina mooreana Gabb with T. papyria Conrad (1833b, p. 41) and placed the species questionably in the section Pero­nidia. Harris (1919, pp. 159-160) too placed T. mooreana Gabb in the synony­my of T. papyria Conrad but retained the species in Tellina s.l. Miss Julia Gardner (1945, p. 106) regarded the two as sep­arate, but synchronous, closely related species of Tellina s.l. and suggested re­taining the name mooreana for the west­ern Gulf f onn. However, if the respective type locali­ties may be considered as characteristic of the stratigraphic levels the species oc­cupy, it is clear that T. papyria Conrad from the Cook Mountain fonnation at Claiborne Bluff in Alabama is strati­graphically higher than Tellina (Eurytelli­na} mooreana Gabh from the Stone City beds of Stone City Bluff in Texas. Besides the difference in stratigraphical level there are also some distinctions in sculp­ture and outline. Tellina (Eurytellina} panria Conrad lacks impressed concen­tric lines, and its posterior extremity is not angulate; its posterior end is vertical­ly subtruncate and rounded. The last­mentioned species is figured for compari­son; see Plate 15, figures 7 ,8. Type data.-Monotype, double-valved individual, no. 13260, Academy of Natur­al Sciences of Philadelphia. The accom­panying label in Gabb's handwriting is as follows: "Type/ Tellina Mooreana Gabb/Jour. Acad. 2. s. v. 4. pl 67. f. 58/ Eocene/ Caldwell Co/ Texas/ W M G." (Note made by Stenzel in 1948.) Type locality.-Presumably Stone City Bluff; compare discussion under "Loca­tion" (pp. 10-11). Geologic horizon.-The species occurs in the Viesca member of the Weches for­mation, the Stone City beds, and ques­tionably in the Wheelock member of the Cook Mountain formation, Claiborne group, Middle Eocene. Subgenus MOERELLA Flseher, 1887 Autkor.-Fischer, P. H. (1887) Man­uel Je conchyliologie et de paleontologie conchyliologique, etc., Paris, F. Savy, p. 1147. [June 15] Type species.-"T. donacina, Linne'' == Tellina (Moerella) donacina Linne. Type designation.-Monotypic. First description of type species.-Lin­ ne, Carl ( 1758) Systema naturae, etc., ed. 10, vol. 1, p. 676. Compare Dodge (1952, p. 48). Type loca/,ity and horizon of type spe­ cU!s.-Living in European seas from the Hebrides to the Azores and into the Med­iterranean and Black Seas. Subgeneric description.-Shell highly inequilateral, slightly inequivalve; ovate in outline (height is 45 to 62 percent of greatest length). Umhones greatly pos­terior (at about 0.61 of greatest length of valve) and inconspicuous. Anterior end much produced, well rounded; posterior end acuminate and rostrate; the rostrum defined by a rounded, obtuse riqge. Ven­tral margin broadly rounded; dorsal mar­gin anterior of the umho is very long and straight. Right lateral hinge teeth strong, the anterior one closer to the umbo; left later­al teeth weak, the anterior one the weak­er of the two. Sculpture consists of weak growth lines or sublamellate concentric threads. Range of subgenus.-Not known satis­factorily. Known in the Gulf Coastal Plain from the Middle Eocene Stone City bed~ at least; living today. TELLINA (MOERELLA) PETROPOLITANA Stenzel & Krause, n. sp. Pl. 22, figs. 10, 11 Description.-Shell very thin and frag­ile, to about 30 mm long, elongately ovate (height is about 49 percent of the greatest length), compressed (width is about 17 percent of height). Umhones greatly posterior (at about 0.61 of great­est length of valve) and quite inconspic­uous; um.bones and dorsal margins form an obtuse angle of about 154 degrees. The antero-dorsal margin very long and nearly straight. Anterior end much pro­duce(} and well rounded. Ventral margin broadly and evenly rounded. Posterior end rostrate; the rounded angle of the extremity is about 106 degrees. From the posterior extremity the margin curves rapidly and fairly evenly into the short, gently sigrnoidal postero-dorsal margin. The posterior tip of the right valve is bent outward slightly; the sigmoid fold of the valve commissure is very slight. In the right valve the posterior lateral hinge tooth is long and very narrow and projects only very slightly; it is about 3.8 mm from the umho. Pallial sinus con­nected to the posterior adductor muscle imprint by a glossy line, 1.6 mm long. Rostrum defined by a rounded, very obtuse ridge. Surface of valve glossy and smooth; growth wrinkles low and glossy over the entire disk inclusive of the rostral . region. Dimensions.-The monotype is broken at the anterior end, so the greatest length is estimated. Greatest length, 27.4 mm est.; height perpendicular to greatest length, 13.4 mm; width of valve, 2.3 mm. Remarks.-This species differs from Tellina (Eurytellina} nworeana Gahb by its inconspicuous umbones, the much more produced anterior part, the presence of a rostral ridge, and the absence of impressed concentric lines. Type data.-The monotype is a soli­tary right valve, deposited at the Bureau of Economic Geology, The University of Texas, Austin, Texas. Type locality.-Stone City Bluff. Geologic horizon.-T h e monotype is from bed ( s) of the section exposed at Stone City Bluff; Stone City beds, Clai­borne group, Middle Eocene. Superf amily l\·IACTRICAE Familv J\tlACTRIDAE Subfamily KYM.ia\TOXINAE, new subfamily Genus KYMATOX Stenzel & Krause, n. gen. Authors.-Stenzel, H. B., & Krause, E. K., in Stenzel, H. B., Krause, E. K., & Twining, J. T. (1956). Type species.-Kymatox praelapidosus Stenzel & Krause, n. sp. (Pl. 15, figs. 15, 16, and text fig. 20). broad and shallow radial depression ly­ing anterior to a thin, raised, somewhat uneven radial thread. Rostral area, pos­tero-dorsal of the thread, is flat to gently convex. Antero-dorsal margin nearly straight and gently sloping; postero-dor­sal margin convexly arched. Lunule unde­fined or faintly defined by a slight ridge, elongately cordiform in outline, about 17 mm long and 10 mm wide in adults. Hinge plate thin, oblique, that is slop· ing upward and outward so that it is at­tached at some distance beneath the dor­sal edges of the valve and the whole hinge armature is sunken or excavate (fig. 20). Resilifer shallow, high-triangular, in­ Type designation.-Herewith, that is, original. See also page 180. Type locality and horizon of type spe­ cies.-Stone City Bluff. Stone City beds, Claiborne group, Middle Eocene. Generic description.-Shell thin and fragile, to about 70 mm long, equivalve, ovate (height is 71 to 85 percent of length), moderately to strongly inflated (width of double valves is 48 to 69 percent of height) , gaping narrowly at the posterior end. Umhones anterior to slightly anterior (at 0.33 to 0.43 of length of valve) , pro­sogyrate, tumid, but rising only slightly above the dorsal margins of the valves. Anterior end short and well rounded; ventral margin broadly rounded; poste­rior end produced, rounded, and rostrate. Rostrum delimited antero-ventrally by a clined downward and to the posterior. Hinge teeth thin, blade-like. Anterior to its resilifer the left valve has: a very thin vertical posterior cardinal tooth ( 4b) , forming a limiting wall at the anterior margin .of the resilifer; a thicker and more projecting, inverted L-shaped anterior cardinal tooth (2a and 2b) , the vertical limb (2b) of which is separated from the posterior cardinal tooth ( 4b) by merely a narrow cleft and the horizontal limb (2a) of which is separated from the dorsal valve margin by a narrow gap; and an oblique, comparatively short anterior lateral hinge tooth (LAii), the posterior end of which touches the horizontal limb (2a) from be­low and the anterior end of which runs into the hinge plate margin. Posterior to its resilifer the left valve has a long, ob .. lique posterior lateral hinge tooth (LPII) extending from the umho to the vcn~ral margin of the hinge plate and increasing in height toward the posterior. The tooth is slightly curved over toward the wide gap between it and the postero-dorsal shell margin; its anterior end is covered over and connected with the postero-dor­sal shell margin by the narrow-triangular nymph of the external ligament which curves down into the resilifer without be­ing separated from it by a shelly septum. Anterior to its resilifer the right valve has: a median cardinal tooth ( 3a and 3b), of the shape of an inverted L, the vertical limb (3b) of which is a wall at the anterior margin of the resilifer and the horizontal limb (3a) of which is sep­arated from the dorsal valve margin by a narrow gap; and an oblique, compara­tively short anterior lateral tooth (LAI), the posterior end of which touches the horizontal limb (3a) from below and the anterior end of which runs into the ven­tral hinge plate margin. Posterior to its resilifer the right valve has a long, ob­lique posterior lateral hinge tooth (LPI), similar to that of the left valve (LPII), and a shorter posterior lateral hinge tooth (LPill), which is half as long and dorsal of and slightly divergent from the former, but which is distinctly separate from, though next to, the postero-dorsal valve margin. Of the two adductor muscle im­prints the anterior one is the smaller, ver­tically elongate, and about t'-vice as high as it is long; the posterior one is sub­pentagonal and occupies about twice the area of the other one. Pallial sinus long and narrow, produced almost to the an­terior adductor muscle imprint. Sculpture consists of fine low concen­tric threads superimposed on broader concentric undulations, rounded on top. The fine threads t:xtend also over rostral area and lunule; but the undulations dis­appear either at the radial rostral thread or at the anterior margin of the shallow radial depression, also at the margin of the lunule in early growth stages and a good distance from that margin in the later growth stages. Only one of the species has vermiculate sculpture, that is, fine un­even and discontinuous radial threads which run over the concentric undulations. Range of genus.-The genus is re­stricted to the Weches, Stone City, Cook Mountain, and Gosport formations of the Claiborne group, Middle Eocene, and their local equivalents. Remarks.-The generic name Kymatox is of masculine gender, is derived from the Greek adjective kymatias meaning billowy, and refers to the concentric un­dulations. See also page 180. This new genus is generally known under the name Pteropsis Conrad (1860, p. 296). Inasmuch as the name Pteropsis 'vas used earlier for a genus of coelen­terates (Rafinesque, C. S., 1814, Defini­zioni di 36 nuovi generi di animali marini della Sicilia: Specchio delle scienze o giornale enciclopedico di Sicilia, etc., vol. 2, no. 12, p. 166, December I; seen ·and checked by Stenzel) , it is necessary to re­name the pelecypod genus Pteropsis Conrad, 1860. On purpose we are not merely substituting a new name, but we are establishing an entirely new genus with another type species and a modern generic definition, because Conrad's Pteropsis was based on a species the re· mains of which are exceedingly rare and fragmentary, whereas the new type species can he collected more readily in suf­ficiently well-preserved individuals. In view of these facts we are giving here pertinent data on Pteropsis Conrad, 1860. Author.-Conrad, T. A. (1860) Descrip­tions of new species of Cretaceous and Eocene fossils of Mississippi and Ala­bama: Acad. Nat. Sci. Philadelphia Jour., ser. 2, vol. 4, pt. 3, p. 296. Type species.­"Pteropsis papyria, ( Lutraria.} Conrad." = Lutraria papyria Conrad = Kymatox papyria (Conrad). Type designation.­Monotypic. First description of type species.--Conrad, T. A. (1833b) Fossil shells of the Tertiary formations of North America, Philadelphia, vol. l, no. 4, p. 41 [November 26, 1833]; and pl. 19, fig. 7 of the Harris reprint (1893) [plate 19 was apparently omitted from original publi­cation]. Described as Lutraria papyria Conrad. Type locality and horizon of type species.-Claibome Bluff on left bank of the Alabama River, T. 7 N., R. 5 E., west­central Monroe County, Alabama. Gos­ port sand, Claiborne group, Middle Eocene. Nearly all fossil individuals of this genus have their two valves closed, so tightly are the hinge teeth interlocked. They are generally preserved as the in­ternal molds of the closed shell and have no shell wall material left. Distortion caused by the compaction of the enclosing sediment has produced diversely shaped molds. These internal molds have curious deep incisions on the dorsum which are the imprints left by the thin, laminar hinge plate and teeth; see Plate 15, figures 11-14. . Cox (1931, pp. 183-184) proposed the genus Blagrave'ia for one shell and several internal molds from India and Somali­land and placed the genus questionably in the family Veneridae. The description and figures indicate it is very similar to, but apparently not identical with, Kyma­tox Stenzel & Krause. The two species of Blagraveia figured by Cox (1931, pl. 21, figs. 3, 5-11 ) differ from K ymatox in having a truncate posterior end, a deep escutcheon, and sculpture which continues to the edge of the escutcheon because there is no radial rostral ridge or thread. The sculpture of Kymatox stops at the radial rostral ridge and does not reach the dorsal margin. The dentition of Blagraveia is known only from impressions on internal molds, and the interior is unknown. Cox (1931, p. 183) stated that there are ap­parently two cardinal teeth in each valve, "the right anterior prominent, hut nar­row, the right posterior widely divergent, the left anterior strong and bifid, fitting between the two teeth of the other valve, the left posterior inconspicuous. True lat.era! teeth absent." Cox also noted on the interior molds of the shells, on each side anterior to the umho, a deep, narrow, elongate slit which corresponds in po­sition to the groove circumscribing the lunule. He concluded that the groove round the lunule is represented inside the shell by a thin, projecting lamina, which gives rise to the deep slit on the internal mold. Internal molds of Kymatox show such a pair of deep grooves too, and the shells themselves demonstrate that the grooves are caused by a thin projecting lamina, which is the hinge plate, the at­tachment of which coincides with the groove circumscribing the lunule. Hence we are led to believe that BlagraveUJ. is a member of the family Mactridae. KYMATOX LAPIDOSUS (Conrad) Pl. 15, figs. 11-14 1834 Lutraria lapidosa Conrad. CONRAD, T. ·A., Catalogue of the fossil shells of the Tertiary formations of the United States, etc., in MoRTON, S. G. (1834) Synopsis of the or­ganic remains of the Cretaceous group of the United States, Philadelphia, Key & Biddle, p. 8 of appendix. [ nomen nudum] 1846 Lutraria lapUlosa CONRAD,-T. A., Observa­tions on the Eocene formation of the United States, with descriptions of species of shells, &c. occurring in it: Am. Jour. Sci., ser. 2, vol. 1, no. 2. pp. 215-216, pl. 2 [not pl. 1 as stated in text], fig. 7. [May] 1848 Lutraria petrosa Conrad + Lutraria lapi­dosa Conrad. TuoMEY, MICHAEL, Report on the geology of South Carolina, Co­lumbia, pp. 148, 151, 153, 157, 159, 161, 168. 1848 Lutraria petrosa. CONRAD, T. A., Observa­tions on the ·Eocene formation. and descrip­tions of one hundred and five new fossils of that period, from the vicinity of Vicks· burg, Mississippi, with an Appendix: Acad. NaL Sci. Philadelphia Proc. 1847, vol 3, no. 11, p. 298. 1863 Astarte Conradi DANA, J. D., Manual of geology, etc., ed. 1, pp. 516, 517, fig. 800. [no description, figure only; also in eds. 2. 3, and 4.] 1865 Pteropsis lapidosa CONRAD, T. A., Cata­logue of the Eocene and Oligocene Testacea of the United States: Am. Jour. Con­chology, vol. 1, no. 1, p. 4. 1884 "Astarte Conradi (= young of Crassatella a/,uz)" HEILPRIN, ANGELO, The Tertiary geology of the eastern. and southern United States: Acad. Nat. Sci. Philadelphia Jour., ser. 2, vol 9, pt. 1, p. 152. 1886 Lutraria Conradi Dana. ALDRICH, T. H., Preliminary report on the Tertiary fossils of Alabama and Mississippi: Alabama Geol. Survey Bull. 1, p. 39. pl. 4, fig. 7. 1894 Ptero psis Conradi Dana + Ptero psis lapi­dosa Co11;rad. DANA, J. D., Manual of geol­ogy, etc., ed. 4, pp. 897, 916, fig. 1483. [no description, figure only.] 1896 Pteropsis conradi Dana. VAUGHAN, T. W., A brief contribution to the geology and paleontology of northwestern Louisiana : U. S. Geol. Survey Bull. 142, pp. 20, 48. 1898 Ptero psis lapidosa Conrad. DALL, W. H., Contributions to the Tertiary fauna of Florida, etc.: Wagner Free Inst. Sci. Trans., vol. 3, pt. 4, p. 881. 1919 Pteropsis lapidosa Conrad. HARRIS, G. D., Pelecypoda of the St. Maurice and Clai­borne stages: Bull. Am. Paleontology, vol. 6, no. 31, pp. 178--179, pl. 54, figs. 14, 15. 1921 Pteropsis harrisi VAN WINKLE, K. E. H., Illustrations and descriptions of foEsil Mollusca contained in the paleontological collections at Cornell University: Bull. Am. Paleontology, vol. 8, no. 36, p. 355 of volume, pl. 15 of volume, figs. 12, 13. 1931 Astarte ? RENICK, B. C., & 'STENZEL, H. B., The lower Claiborne on the Brazos River, Texas: Univ. Texas Bull. 3101, p. 104, no. 19 (part; locality 4 only). 1936 Pteropsis lapidosa (Conrad). COOKE, C. W., Geology of the Coastal Plain of South Carolina: U. S. Geol. Survey Bull. 867, pp. 58, 64, 65. 1945 Pteropsis lapidosa Conrad + lncertae sedis. GARDNER, JULIA, Mollusca of the Tertiary formations of northeastern Mex­ico: Geol. Soc. AmeriGa Mem. 11, pp. 112-113, pl. 9, figs. 30, 32. 1952 Pteropsis lapidosa Conrad. CooKE, C. W., & MACNEIL, F. S., Tertiary stratigraphy of South Carolina: U. S. Geol. Survey Prof. Paper 243-B, p. 24. Original description.-Obliquely ovate, convex, with rather distinct large concentric sulci, ob­solete towards the base; summits very elevated, from which the anterior and posterior dorsal margins decline very obliquely; anterior ex­tremity angulated; posterior side cuneiform to­wards the end margin, which is acutely rounded or suoangulated; anterior basal margin very obli'lue, s11btrunr.ated. (Plate I, fig. 7.) Orangeburg, S. C. I have hut one specimen, a cast in indurated clay, without a trace of the original shell re­maining upon it. [Conrad, 1846b, pp. 215-216.] Revised description.-Shell to about 50 mm long, ovate (height is 75 to 85 per­cent of length), moderately to strongly in­flated (width of double valves is 55 to 66 percent of height). Umbones anterior, at 0.25 to 0.41 of length of valve. Lunule shal­low, to 17 mm long and 10 mm wide, de­fined by a gentle obtuse marginal ridge, which is crossed by the concentric threads but not by the undulations. In the early growth stages the concen­tric undulations are regular, closely spaced (about 10.8 per centimeter), and slope more st.eeply on the dorsal than on the ventral side; later they become less regular, more widely spaced (about 4.6 per centimeter), unevenly elevated, and finally obsolete near the ventral margin. The concentric undulations disappear at the radial rostral thread in early growth stages; later they disappear progressively more anteriorly, and in adults they disap­pear at the anterior margin of the broad shallow depression which lies anterior to the radial rostral thread. Dimensions.-The following appar­ent! y undistorted double-valve individuals were measured in miltimeters. However, nearly all measurements of the length of the shell are vitiated somewhat, because the very narro'v posterior extremity is amiss on nearly all individuals. LOCALITY LENGTH HEIGHT WIDTH Vance's Ferry, South Carolina; Coll. of Acad. Nat. Sci. Philadelphia; Dr. Blanding-mono­type *44.0 33.5 18.6 Same lot * 39.0 est. 30.0 17.0 *39.5 est. 30.6 18.4 Vance's Ferry, South Carolina; Coll. of Acad. Nat. Sci. Philadelphia; Dr. Morton *47.8 39.0 25.1 Claiborne, Alabama; Coll. of Acad. Nat. Sci. Philadelphia, no. 9105 33.4 27.3 17.0 Claiborne Bluff, Alabama · • 3~.o 24.6 13.4 27.0 est. 23.9 13.4 Hurricane Bayou, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-2 *39.5 est. 31.4 20.7 *16.7 est. 13.3 7.9 NOTE: Those marked by an asterisk are interior molds without remains of the shell itself. Remarks.-Conrad (1848a, p. 298) and Tuomey (1848, p. 148) listed, but did not describe, a Lutraria petrosa Conrad. This nomen nudum is probably the result of a confusion of languages for the Greek petrosunded ribs. According to the figures and description the shell outline is sub-quad­rangular. Until exact data as to locality and stratigraphic position of this species are obtained, its usefulness will remain impaired. Type data.-V. S. National Museum, catalog no. 369240. Type locality.-Stone City Bluff. Geologic horizon.-The geologic hori­ zon given by Miss Gardner was deter­mined before it was known that two for­mations are exposed at the type locality; hence it is now uncertain from which one of the two the soecies was collected. Not a single valve of any V erticordia has been found by us in either the Stone City beds or the Cook Mountain formation at Stone City Bluff; hence it cannot be irrefutably decided from which of the two formations V. (T.) satex Gardner came. However, nowhere has any V erticordia been · found in exposures of the Stone City beds from the Sabine River to the Colorado River in Texas. On the other hand, Verticord"ia (Trigonulina} satex Gardner has been col­lected from other exposures of the Cook Mountain formation. Hence, the species was very probably collected from the Cook Mountain formation exposed at the upper part of Stone City Bluff. Also, the gen­eral facies of the Stone City beds makes it highly unlikely that they would contain a deep-water form such as Verticordia. Material at hand and believed to be referable to this species is from the f oi­l owing localities: Cook Mountain formation, Claiborne group, Middle Eocene, of St. Maurice, Winn , Parish, Louisiana; Bur. Econ. Geology locality no. La.· 15. Cook Mountain formation, Claiborne group, Middle Eocene, in gullies north of the old Quit­man-Liberty Hill road and west of Madden Creek, 3.6 miles west on road from Quitman railroad crossing, section 15, T. 16 N., R. 3 W., Jackson Parish, Louisiana; Bur. Econ. Geology locality no. La.-7. While our publication was in page proof, a short article was published by H. E. Vokes in which a new name Pteropsella was proposed for Pteropsis Conrad, 1860, with Lutraria papyria Conrad, 1833, = Pteropsis papyr"ia (Conrad), 1860, as the type species. The new name Pteropsella therefore has publication priority over the name Kymatox Stenzel & Krause, proposed in the present publication on pages 124-­ 126. Whether or not Pteropsella has been used elsewhere before 1956 and is therefore preoccupied, we have not endeavored to check. If it is not preoccupied, it will have to be used in place of Kymatox. The reference is Vokes, H. E. (1956) Notes on, and rectifications of, pelecypod nomenclature: Jour. Paleontology, vol. 30, no. 3, p. 763. [July] Table 3. Distribution of the Pelecypoda of the Stone City beds at Stone City Bluff. ~z zQ ABUNDANT => r­ .. z RELATIVE 0 <{ -::2:::2: COMMON -a::: ABUNDANCE: ~o 0 LL FREQUENT 0 (.) RARE I. Nucula (N.) mauricensis Harris----------­ 2. Calorhadia (C.) compsa (Gabb)----------­ 3. C. (Litorhadia) petropolitana S. & K.-------­ 4. C. (L?) evanescentior S. & K. ----------­ 5. Orthoyoldia psammotaea Dall----------­ 6. Arca (A.) petropolitana S. & K . ----------_ 7. Barbatia (B.) uxorispalmeri S. & K.-------­ 8. Glycymeris petropolitana s, & T. -·-------­ 9. Pachecoa {P.) pulchra (Gabb)----------­ 10 . P . (P.) sabinica (Harris)-----------­ 18. Anemia ephippioides Gabb-------""----­ 19. Venericardia (Venericor) planicosta densata (Conrad)­ 20. V. (Claibornicardia) trapaquara Harris-----­ 21. Diplodonta (D.) petropolitana Stenzel-------­ 22. Abra (A.) petropolitana Stenzel--------­ 23. Tellina (Euryte!lina) mooreana Gabb------­ 24. T . (Moerella) petropolitana S. & K.---~---­ 25. Kymatox praelapidosus S. & K.---------­ 26. Katherine!la smithvillensis S. & K.-------­ 27. Pitar (Calpitaria) petropolitanus S. & K.------­ 28. P . (C .) texibrazus S. & K.------------­ 30. Pholadomya petropolitana S. & T.,--------­ 31. Caryocorbula deusseni (Gardner)--------­ 32. Notocorbula texana (Gabb)-----------­ 33. Vokesula smithvillensis petropolitana S. & T .---­ -? ? -? STONE CITY BLUFF l.J.j _J SPARTA STONE CITY BEDS CD 0 60 50 45 40 35 11 . Mauricia houstonia (Harris)-----------••I--+ 12. Atrina cawcawensi~ (Harris)----------­ 13. Pteria (P.) petropolitana S. & T.---------­ 14. Eburneopecten scintillatus Conrad--------­ 15. Lima (Limatulella) petropolitana S. & T.-----­ 16 . C.ubitostrea (C .) petropolitana S. & T.-------­ 17. Crassostrea frionis (Harris)-------------? 34. Verticordia (Trigonulina) satex Gardner-----_....,_,.__,.._ 1 Number of species per bed--------------3 10 l21 I 17 I 22 4 07 0 0 0 0 4 5 4 STATISTICAL ANALYSIS OF VOKESULA SlVIITHVILLENSIS (HARRIS) John T. Twining In comparing V okesula smithvillensis (Harris) from the Stone City beds with specimens from ·the type locality in the Weches formation it was noted that, in ad­dition to being smaller, the Stone City forms have finer concentric ribs. These differences are not readily recognizable on single individuals but are readily demonstrable by statistical methods ap­ . plied to a series of individuals. Five separate samples were selected. Each sample consisted of the right valves of 50 individuals. The stratigraphic ho­rizons and localities of the samples were as follows: LOCALITY SAMPLE NO. STRATIGRAPHIC POSITION (BUR.ECON.GEOLOGY LOCALITY NO.) (5) Cook Mountain formation, Hurricane lentil Hurricane Bayou, Houston County, Texas ( 113-T-2) (4) Cook Moun tain formation, Wheelock member, bed (ad) Stone City Bluff, Burleson County, Texas (26-T-1) (3) Stone City beds, bed (w) Stone City Bluff, Burleson County, Texas (26-T-l) (2) Stone City beds, bed (u) Stone City Bluff, Burleson County, Texas (26-T-1) (1) Weches formation, Viesca member Smithville, Bastrop County, Texas (11-T-2) The height and length of all valves were measured, and a "rib count'' was made on 25 valves from each sample. The "rib count" is the number of concentric ribs in a specific unit of length, oriented nor­mal to the hinge line and measured at a distance of 2 mm below the top of the valve as seen when one looks straight down on the valve at right angles to the plane of the valve commissure. This number gives a measure of the relative size and crowding of the ribs at a comparative, al­though arbitrarily selected, growth stage. The measuring was done under a micro­scope using a micrometer ocular; after­ wards the rib count was recalculated to number of ribs per 2 mm as the specific unit of length. The averages of the meas­urements are given below. AVERAGES NUMBER SAMPLE HEIGHT OF LENGTH OF OF RIBS NO. RIGHT VALVE RIGHT VALVE PER 2 MM (5) 5.29 5.83 8.0 (4) 5.04 5.42 8.0 (3) 5.11 5.37 8.0 (2) 6.95 7.26 7.5 (1) 8.16 9.67 6.0 A scattergram was constructed by plot­ting the rib count as the ordinate against the height of the right valve as the ab­scissa {fig. 28) . This scatter gram shows two distinct groups, that is, the Weches sample ( 1) and the uppermost Stone City and two Cook Mountain samples ( 3) , { 4) , and (5) , while the sample ( 2) from the bed { u) of the Stone City beds shows as an intermediate form. A very similar arrange­ment is obtained by plotting a set of f re­quency curves (fig. 29). Here the number of individuals with rib counts falling with­in designated class ranges ( 6.8-7.2; 7.3­ 7.7; 7.8--8.2, etc.) was plotted against the midpoint of the corresponding class range. Again the result is a definite separation of sample (1) from samples (3), (4), and (5), and sample (2) lies in an intermedi­ ate position. Statistical calculations based on the rib count data substantiate these findings. The calculations were made in accordance with the methods and formulae given by Simp­ son & Roe (1939) and Burma (1948). The results of the calculations are given in table 4. The standard deviation ( u) is a meas­ure of the tendency of the individuals of the sample to group themselves about a mean and gives an indication of the vari­ability of the population; or, the smaller the value of the standard deviation the less variable is the sample, and the larger its value the greater is the variability. A com­parison of the values obtained as shown 10 .0 - 2 0 ('IJ en .0 a: -0 5 .0 /~\ I I I I \ I VA--·A· I ;-\ I \ \ \ / \ \ I I \ I 1xx \•xx\ / I \ \ I I \ \ I \ I I ~ \ \ I AA' \ I II xx .,·8 8x"-, • ,\ •f8 "'-'I .........._ 'I I J ''I\ I v ~A x A x:x I......: ...... 1 I , r ~••. ~i~ \ I I \ ,' \ I I i ,. 't8AAA x xx& d /• A \I/ I\ ' I f I I' Ill. ' ~ ll.J<'\A.Xx& ~.h '-~''/ \ .. ~ --\ ,~~11 \ \ __.;:;;;.,"' ........_ \ ~7 "'-~/ ~ \ \ ' ' -~ Sample Points and Stratigraphic ~ Number Circumference Position tiS Q:'. /8-.... 5 --·--Hurricane Lentil } -~ I I ', ' 4 ---x---Wheelock Member, ~ I ' bed ad § I ' ' d\ 3 --8----Stone City Beds, ~ bed w ~ \ __,_, --[!)----­ \ 2 Stone City Beds, a bed u\ ---0---Viesca Member of \ Weches Formation \ I I tj I I I I o II I I I l 8 8 \ \ \ \ \ \ \ \ \ 8 8~8 .i;lki--------0-----~ l!J ,,.. I 7 ,,/ I I ,,/ I ( / I • I 0 00 q0000 0 0 (.) \ l \ I \ I \ ' I / _______,,_ I ' ~ ~.... '\.0% Qg 0 0 0 0 Q ..., /' ................................ ,/"' "0 0 0 9/ \ / \ I /b/'// / 5.0 10.0 __ Heioht of Right Valve in Mi I Ii meters Fie. 28. Scattergram of five samples of populations of subspecies of Vokesula smithvillensis (Harris) taken front different stratigraphic levels in the Claiborne group of Texas. The samples are numbered beginning with the stratigraphically lowest and ending with the stratigraphically highest population. Stone Cjty Pelecypoda 5.0 10.0 Height of Right Valve in Millimeters 50 -c Cl> u ~ Cl> a.. c V> .g 0 25 > "O c 0 - .... .8 E ::J z A Sample :'\ Number Stratigraphic Position I \ 5 • Hurricane Lentil }Cook Mountain ! \ 4 x Wheelock Member, bed ad Formation I \ A 3 Stone City Beds, bed w 0 f \ 2 Stone City Beds, bed u I \ 0 Viesca Member of Weches Formation : I I\ I X I c:J / \ I \ I " I/ \' /I ,\ I I \ \ I \ ~ I ~\ I \ I I \ I \ : \ ~ ', II \ 1'\ I \ I \ I \ l I \ / \ : \ I \ I I ~ I I I \ ~ \ \ / I I 1 \ ' •l I I \ I \ ~ I II o, ' \ C!>------d "' I \ \ I "o I I I \ ~, I '\ , A' ........ \ \ ~,..~ ~ \ \ x' we can assume that each sample repre­sents only one species (fig. 30). Since the mean of any sample collected at random cannot be expected to be iden­tical with the mean of the entire popula­tion, direct comparisons of the means of individual samples are of little value. If some multiple of the standard error of the mean is added to and subtracted from the mean of the sample, a range is obtained within which the mean of the corresp::>nd­ing population may be expected to fall. By using three times the standard error of the mean (M -3aM and M + 30M) a range is obtained within which the mean of the population may be expected to fall 99.7 percent of the time. A com­parison of the ranges thus obtained will give a close approximation to a direct com­parison of the various populations. If the mean of one sample falls within the range of another the two samples could not be ' ­ separated on this basis alone, because this situation would indicate that the means of the two populations from which the sam­ples were taken might be equal or nearly so. On the other hand, if the mea:µ of the first sample does not fall within the ex;. pected limits of the other, the means of the corresponding populations cannot be the same and the samples have to be re­garded as representing two different forms. The calculated ranges of the means of the five samples used in this study are tabulated in table 4 and presented graphi­cally in figure 3 la. It is seen that the mean of sample (1) does not fall within the ranges of any of the other samples, and there£ ore it must be regarded as repre­senting a distinct form. The means of samples ( 2) , (3) , ( 4) , and { 5) all fall within the ranges of each other, and on this basis all these samples are representa­tives of the same form. According to Burma (1948, p. 731) a more accurate range of the means is obtained by using the formula M + 3y'2uM2• This formula results in. a very similar situation to that shown in figure 3la. The one main difference lies in table 4 shows that the Weches sample (1) is the least variable, while sample ( 2) from bed ( u) of the Stone City beds is the most variable. If some multiple of the standard devia­tion be added to and subtracted from the mean (M) of the sample, the expected limits of variability of the population may be obtained to any degree of accuracy de­sirable. The value most generally used is three times the standard deviation (M -3u and M + 3n) , which results in lim­its that include 99. 7 percent of the pop­ulation. This means that not more than 3 individuals in 1,000 may be expected to fall outside these limits. All the measure­ments made in this study fall within the limits of their respective samples; thus 2 3 4 5 Sample Number 2 FIG. 30. Expected limits of the variability in the number of ribs per 2.0 millimeters in sub­species of V okesula smithvillensis (Harris) . The arithmetic mean of each of the five samples of the population is shown by a <;:ymbol, and the calculated expected limits by a bar. The samples and the individuals measured are the same as those of figure 28. 10 M+3o­ 9 8 - :.?! - en c '­ 0 Q,) Q) ~ E -.~ ·­ 7 G> E :? = ._ CD z 4 3 M-3o­ x II 10 9 (/) '­ a... 7 (/) ..0 a: 0 6 '­ t seen] MACNEIL, F. S. (1937) The systematic position of the pelecypod genus Trinacria: Washington Acad. Sci. Jour., vol. 27, no. 11, pp. 452-458, 1 fig. [November 15] (1944) Oligocene stratigraphy of southeastern United States: Am. Assoc. Pe­troleum Geologists Bull., vol. 28 no. 9, pp. 1313-1354, 1 text fig. [September] (1951) Nucula austinclarki, n. sp., a concentrically sculptured Nucu/,a from the Lisbon formation of Alabama: Washington Acad. Sci. Jour., vol. 41, no. 1, pp. 12-14, 2 figs. [January 18] ( 1954) Stenzelia, new name for Trinacriella MacNeil: Jour. Paleontology, vol. 28, no. 2, p. 217. [May 11 MANSFIELD, w. c. (1927) Some peculiar fossil forms from Maryland: U. S. Nat. Mus. Proc., vol. 71, no. 2688, art. 16, pp. 1-9, pis. 1-5. (1930) Some peculiar spiral fossil forms from California and Mexico: ibidem, vol. 77, no. 2836, art. 13, pp. 1-3, pis. 1, 2. MAYER, C. ( 1868) Catalogue systematique et descri ptif des fossiles des terrains tertiaires que se trouvent au Musee Federal de Zurich, vol. 3. [not seen1 MEEK, F. B. (1864) Check list of the inverte­brate fossils of North America. Cretaceous and Jur8.$iC: Smithsonian Misc. Coll., vol. 7, no. 177, art. 8, 40 pp. [April] MEYER, OTTO ( 1885) The genealogy and the age of the species in the southern Old-tertiary [3 pts.]: Am. Jour. Sci. ser. 3, vol. 29, no. 174, art. 59, pp. 457-468 [June]; vol. 30, no. 175, art. 10, pp. 60-72, 1 text fi~. [July]; vol. 30, no. 180, art. 53, pp. 421-435, 1 text fig. [December]. ----(1886a) Contributions to the Eocene paleontology of Alabama and Mississippi: Alabama Geol. Survey Bull. 1, pt. 2, pp. 61­85, pls. 1-3. ( 1886b) Observations on the Terti­ary and Grand Gulf of Mississippi: Am. Jour. Sci., ser. 3, vol. ~2 (or 132), no. 187, art. 3, pp. 20-25. [July] ( 1887) Beitra~ zur Kenntnis der Fauna des Alttertiiirs von Mississippi und Ala­bama: Senckenberg. naturf. Gesell. Ber., 1887, pt. 2, Vortrage und Abhandlungen, pp. 3-22, pls. I, 2. MEYER, OTTO, &ALDRICH, T. H. (1886) The Ter­tiary fauna of Newton and Wautuhbee, Mi~.: Cincinnati Soc. Nat. History J our., vol. 9, no. 2, pp. 40-50, pl. 2 [June or July] MoNTAGU, GEORGE (1803) Testacea Britannica; or, Natural history of British shells, etc., pt. 2, 606 pp., 16 pls., London, J. White. ( 1808) Supplement to Testacea Britannica with additional plates, 183 pp., pis. 17-30, London, J. White. MORCH, 0. A. L. ( 1853) Catalo~us conchyliorum . quae reliquit D. Alphonso d'Aguirra & Gadea Comes de Yoldi, etc .• fasc. 2 (Acephala, An­nulata, Cirripedia, Echinodermata), 74 pp., Copenhae.;e~ Ludvig Klein. [April] MooRE, FRANCIS, JR. (1859) Geological sketch of Texas, pp. 91-99, in The Texas Almanac for 1860, 3d no., 314 pp., Galveston, Richard­son & Co. MooRE, H. B. ( l 93la) The specific identification of faecal pellets: Marine Biol. Assoc. United Kingdom J our., new ser., vol. 17, pp. 359-365, 6 text figs. (I93lb) The systematic value of a study of molluscan faeces: Malacological Soc. London Proc., vol. 19, pt. 6, pp. 281-290, pis. 30-33. [November] MORRIS, JOHN, & LYCETT, JoHN (1853) A mono­graph of the Mollusca from the Great Oolite, chiefly from Minchinhampton and the coast of Yorkshire; pt. 2, Bivalves: Paleontographi­cal Soc., vol. 7, pp. 1-80, pis. 1-8. [December] MORTON, S. G. (1833) Supplement to the "Syn­opsis of the organic remains of the ferruginous sand formation of the United States": Am. Jour. Sci., ser. 1, vol. 24, art. 11, pp. 128-132, pis. 9-10. 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(1928) A new fauna from the Cook Mountain Eocene near Smithville, Bastrop County, Texas: ibidem, vol. 2, no. 1, pp. 20--31, 1 text fig., pis. 6, 7. [March] QuENSTEDT, WERNER (1930) Die Anpassung an die grabende Lebensweise in der Geschichte der Solenomyiden und Nuculaceen: Geol. und Pal. Abh., Neue Folge, Bd. 18 (22), Heft I, pp. 1-120, 1 text fig., 3 pis. [October 3] RATHBUN, M. J. (1935) Fossil Crustacea of the Atlantic and Gulf Coastal Plain: Geol. Soc. ·America Spec. Paper 2, 160 pp., 2 text figs., 26 pis. REEVE, L. A. (1843/78) Conchologia Iconica; or, Illustrations of the shells of molluscous ani· m.als, 20 vols., London, Lovell Reeve. [not seen] REINHART, P. W. (1935) Oassification of the pelecypod family Arcidae: Mus. royal histoire nat. Belgique Bull., vol. 11, no. 13, 68 pp., 5 pls. [August] ( 1943) Mesozoic and Cenozoic Arcidae from the Pacific slope of North America: Geol. Soc. America Spec. Paper 47, 117 pp., 3 text figs., 15 pls., 3 tables [June 16] RENICK, B. C., & STENZEL, H. B. (1931) The lower Claiborne on the Brazos River, Texas: . Univ. Texas Bull. 3101, pp. 73-108, text figs. 9-11, pis. 6-7, tables 1, 2 [October] RICHARDS, H. G. (1948) Tertiary invertebrate fossils from newly discovered localities in North and South Carolina; pt. 1 : Acad. Nat. Sci. Philadelphia Notulae Naturae 207, 11 pp., 4 pls. [April 14] ROEMER, FERDINAND (1848) Contributions to the geol'>gy of Texas: Am. Jour. Sci., ser. 2, vol. 6, no. 16, art. 2, pp. 21-28. [July] (1849) Texas, 464 pp., map, Bonn, Adolph Marcus. ( 1852) Die Kreidebildungen von Texas und ihre organischen Einschliisse, 100 pp., 11 pis., Bonn, Adolph Marcus. ----(1935) Texas, 301 pp., copy of map, San Antonio, Standard Printing Co. (Trans­lated by Oswald Mueller from the German edition of 1849.) RoLLIER, Louis (1914) Fossiles nouveaux ou pen connus des terrains secondaires ( Meso­zoiques) du Jura et des con trees environ­nantes, pt. 4: Schweizer. palaont. Gesell. 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ScHUCHERT, CHARLES, & OTHERS (1905) Cata­logue of the type and figured specimens of fossils, minerals, rocks and ores in the De­partment of Geology, United States National Museum; pt. l, Fossil Invertebrates: U. S. NaL Mus. Bull. 53, pt. 1, 704 pp. sceuuE, F. E., KuKENTHAL, w., HEID~ K., & HESSE, R. ( 1927 /29) Nomenclator animalium generum et subgenerum, Bd. 2 C-E: Preuss. Akad. Wiss. Berlin, pp. 477-1298. [p. 853 is dated February 29, 1928] ScHUMACHER, C. F. ( 1817) Essai d'un nouveau systeme des habitations des vers testaces, 287 pp., 22 pls., Copenhagen, Schultz. SeoPOLI, J. A. ( 1777) lntroductio ad historiam naturalem sistens genera lapidum, plantarum et animalium, etc., Prague. [not seen] SHELDON, P. G. (1916) The Atlantic slope areas: Palaeontographics Americana, vol. 1, no. 1, 101 pp., 16 pis. SHERBORN, C. D. (1902) Index animalium, etc.; sect. 1, 1758-1800, 1195 pp., Cambridge Univ. Press. (192:l/33) Index animalium, etc.; sect. 2, 1801-1850, 33 pts., 7056 pp., and sup­plement of 1098 PP·~ British Mus. Nat. History. SHUMARD, G. G. ( 1886) A partial report on the geology of western Texas consisting of a gen­eral geological report and etc., 145 pp., 23 figs., Austin, State Printing Office. SIMPSON, G. G., & RoE, ANNE ( 1939) Quantita­tive zoology; numerical concepts and methods in the study of recent and fossil animals, 414 pp., 52 figs., New York, McGraw-Hill Book Co. SOWERBY, JAMES, & SOWERBY, G. B. (I) ( 1820/34) The genera of recent and fossil shells, for the use of students in conchology and geology, 42 pts., London. Reprinted 1875 by Bernard Quaritch, London, with an added index of viii pp. and the plates numbered. [For dates of various parts, see SHERBORN ( 19'22/33, pL I, p. cxvii) .] SowERBY, JAM~, & SowERBY, J. DEC. (1812/46) 'Mineral conchology of Great Britain; or, Col· oured figures and descriptions of those remains of testaceous animals or shells, etc., 7 vols. in 113 pts. of 648 pls., 1295 pp~, London. [For dates of various parts, see SYKES ( 1906) and SHERBORN (1922/33, pt. 1, p. cxvii) .] SPOONER, G. M., & MooRE, H. B. ( 1940) The ecology of the Tamar estuary: VI. An account of the macrofauna of the intertidal muds: Marine Biol. Assoc. United Kingdom Jour., vol 24, no. 1, pp. 283-330, 12 text figs. [Janu­ary] STENZEL, H. B. ( 1934) Decapod crustaceans from the Middle Eocene of Texas: Jour. Pale­ontology, vol. ~ no. I, pp. 38--56, pis. 6, 7. [March] ( 1935) N autiloids of the genus A.turia from the Eocene of Texas and Ala­bama: ibidem, vol. 9, no. 7, pp. 551-562, pis. 63, 64. [October 24] ----(1936) A new formation in the Oai­borne group: Univ. Texas Bull. 3501, Jan. I, 1935, pp. 267-279., text figs. 34, 35. 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Geology, Rept. Inv. 3. ( 1950) Proposed uniform endings for names of higher categories in zoological systematics: Science, new ser., vol. 112, no. 2899, p. 94. [July 21] (1952a) Notes on surface correla­tion chart and Correlation chart of Eocene at outcrop in eastern Texas, Mississippi, and western Alabama: Mississippi Geol. Soc., Guidebook, 9th field trip, Claiborne of West­em Alabama and eastern Mississippi, p. 32, charL [September 25] ----(1952b) Transgr~ion of the Jack­son group: ibid.em., pp. 36-41. [September 25] STENZEL, H. B., & TURNER, F. E. (1940a) The gastropod genera Cryptochorda and Lap-paria in the Eocene·of the Gulf Coastal Plain: Univ. Stone City Pelecypoda Texas Pub. 3945, Dec. 1, 1939, pp. 795-828", text fig. 128, pls. 43-45. [June] ----, , (19'Wb) Turritellidae from the Paleocene and Eocene of the Gulf Coast: ibidem, pp. 829-846, pls. 46, 47. [June] ----, , (1940c) Lower Terti­ary of the Colorad3 River: Geol. Soc. America, 53d Ann. Meeting, Austin, Texas, Excursions, pp. 66-77, 3 text figs. [December] STEPHENSON, L. W. (1923) Invertebrate fossils of the Upper Cretaceous formations: North Carolina Geol. and Econ. Survey Bull., vol. 5, pt. 1, pp. 1-402, 409--592, 597-604, 6 text figs., pis. 1~100. ----(1953) Larger invertebrate fossils of the Woodbine formation ( Cenomanian) of Texas: U.S. Geol. Survey Prof. Paper 242, 226 pp., 8 text figs., 59 pis. [December 16, 1953; not 1952 as stated on title page] STEWART, R. B. (1930) Gabb's California Creta­ceous and Tertiary type lamellibranchs: Acad. Nat. Sci. Philadelphia Spec. Pub. 3, 314 pp., 5 text figs., 17 pls. [August 9] SToLICZKA, FERDINAND ( 1870/71) Cretaceous fauna of southern India. Vol. 3, The Pele­cypoda, with a review of all known genera of this class, fossil and recent: India Geol. Sur­vey Mem., Palaeontologia lndica, ser. 6, vol. 3, 13 pts., xxii and 537 pp., 50 pis. 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Afrique Occidentale Fran~aise, Direction des Mines Bull. 14, tome 2, pt. 3, Paleontologie, pp. 283-570, pls. 15-40. ToURTELOT, H. A. (1944) Quitman fault zone, Clarke and Wayne counties, Mississippi, Choc­taw County, Alabama: U. S. Geol. Survey Oil and Gas Investigations Prelim. Map 6. TREMLETT, W. E. ( 1953) English Eocene and Oligocene Veneridae: Malacological Soc. Lon­don Proc., vol. 30, pts. 1 & 2, pp. l-21, pls.-1-4, and pt. 3, pp. 55-71, pls. 9-13. [May 21 and September 2, respectively] TROWBRIDGE, A. C. (19'25) A geologic recon­ naissance in the Gulf Coastal Plain of Texas, near the Rio Grande: U. S. Geol. Survey Prof. Paper 131-D, pp. 85-107, pl. 28. [February 12] (1932) Tertiary and Quaternary geology of the lower Rio Grande region, Texas: U. S. Geol. Survey Bull. 837, 260 pp., 76 text figs., 45 pis. TUCKER-ROWLAND, H. I. (1938) The Atlantic and Gulf Coast Tertiary Pectinidae of the United States; sect. 3, Systematic descrip­tions: Mus. royal histoire nat. Belgique Mem., ser. 2, fasc. 13, 76 pp., 6 pis. [July 31] TuoMEY, MICHAEL ( 1848) Report on the geology of South Carolina, 293 pp., 47 text figs., 3 pis., 6 tables, Columbia, A. S. Johnston. TURNER, F. E. (1938) Stratigraphy and Mollusca of the Eocene of western Oregon: Geol. Soc. America Spec. Paper 10, 130 pp., 7 text figs., 22 pis. [June l] VAN WINKLE, K. E. H. (1921) Illustrations and descriptions of fossil Mollusca contained in the paleontological collections at Cornell Uni­versity: Bull. Am. Paleontology, vol. 8, no. 36, pp. 347-358, pl. 15. [March I] VAUGHAN, T. W. (1895) The stratigraphy of northwestern Louisiana: Am. Geologist, vol. 15, no. 4, pp. 205-229, pl. 9. [April] ( 1896) A brief contribution to the geology and paleontology of northwestern Louisiana: U. S. Geol. Survey Bull. 142, 65 pp., 4 pis. VAUGHAN, T. W., & WELLS, J. W. (1943) Revision of the suborders, families, and genera of the Scleractinia: Geol. America Spec. Paper 44, 363 pp., 39 text figs., 51 pls. [March 12] VEATCH, A. C. (1902) The geography and geology of the Sabine River: Louisiana Geol. Survey Re pt. for 1902, pt. 6, special re pt. 3, pp. 101-148, text figs. 10-13, pls. 24-37. VERASTEGUI, PEDRO (1953) The pelecypod genus V enericardia in the Paleoeene and Eocene of western North America: Palaeontographica Americana, vol. 3, no. 25, 514 pp., 22 pis. [Sep­tember 7] VERRILL, A. E., & BusH, K. J. ( 1897) Revision of the genera of Ledidae and Nuculidae of the Atlantic Coast of the United States: Am. Jour. Sci., ser. 4, vol. 3, no. 13, art. 5, pp. 51~3, 22 text figs. [January] ( 1896) Revision of the deep-water Mollusca of the Atlantic Coast of North Americ~ with descriptions of new genera and species; pt. 1, Bivalvia: U. S. Nat. Mus. Proc., vol. 20, no. 1139, pp. 775-901, pls. 71-97. VINCENT, EMILE ( 1897) Observations sur les af­fi.nites de quelques peignes Eocenes: Soc. royale malacologique Belgique Bull., vol. 32, pp. 1-3. [February 13] VOKES, H. E. (1945) Supraspecific groups of the pelecypod family Corbulidae: Am. Mus. Nat. History Bull., vol. 86, art. 1, pp. 1-32, pls. 1-4. [October 10] (1951) Preliminary classification of the genera of the Pelecypoda, 109 mimeo­graphed pp. ( 1956) Notes on, and rectifications of, pelecypod nomenclature: J our. Pal eon· tology, vol. 30, no. 3, pp. 760-761. [July] WADE, BRucE (1926) The fauna of the Ripley formation on Coon Creek, Tennessee: U. S. Geol. Survey Prof. Paper 137, 272 pp., 2 text figs., 72 pis. WALLACE, W. E., JR. (1946) Geologic map of Louisiana, scale I :500,000, Shreveport Geo]. Soc. Bureau of Economic Geology, The Univers"ity of Texas WEAVER, C. E. (1916) Tertiary faunal horizons of western Washington: Washington Univ. [Seattle] Pubs. in Geol, vol. 1, no. I, 67 pp. (1931) Paleontology of the Jurassic and Cretaceous of west central Argentina: ibidem, Mem., vol. I, 594 pp., 62· pls. ( 1943) Paleontology of the marine Tertiary f ormatious of Oregon and Washing­ton: ibidem, Pubs. in Geology, vol. 5, 3 pts., 790 pp., 104 pls. [December 31, 1943, is the date given on the fly leaf.] WINCKWORTH, R. (1929) Marine Mollusca from South India and Ceylon. III: Pinna. With an index to· the recent species of Pinna: Malaco· logical Soc. London Proc., vol. 18, pt. 6, pp. 27f>-..297, 5 text figs. [November 15] ( 1930) Notes on nomenclature ­ 6. Lima and allied genera: ibidem, vol. 19, pt. 3, pp. 115-116. [November 14] (1944) Schmidt's Versuch, 1818: ibidem, vol. 26, pt. I, pp. 23-34. [May 4] W ooo, S. V. ( 1861) A monograph of the Eocene Mollusca; or, Descriptions of shells from the older Tertiaries of England, pt. 1, Bivalves : Palaeontographical Soc., vol. 13, no. 3, 74 pp., 13 pls. WOODRING, W. P. (1925) Miocene mollusks from Bowden, Jamaica: Pelecypods and sea phopods: Carnegie Inst. Washington Pub. 366, 222 pp., 28 pis. [May 20] ----(1938) Lower Pliocene mollusks and echinoids from the ·Los Angeles Basin Cali­fornia, etc.: U. S. Geol. Survey Prof. 'Paper 190, 67 pp., 2 text figs., 9 pls. Woods, HENRY (1900) A monograph of the Cretaceous Lamellibranchia of England. Pt. 2 : Palaeontographical Soc. Mon., vol. for 1900, vol. 54, pp. 7~112, pis. 15-19. [De­cember] YONGE, C. M. (1946) On the habits and adapta­tions o.f Aloidis ( Corbula) gi,bba: Marine Biol. Assoc. United Kingdom Jour., vol. 26, no. 3, pp. 358-376, 14 text figs. [July] (1948) Cleansing mechanism and the function of the fourth pallial aperture · in S pisula subtruncata (De Costa) and Lutraria lutraria (L.) : ibidem, vol. 37, no. 3, pp. 585­596, 8 text figs. ----(1949) On the structure and adapta­tions of the Tellinacea, deposit-feeding Eu­lamellibranchia: Royal Soc. London Philos. Trans., ser. B, no. 609, vol. 23, pp. 29-76, 29 text figs. [September 5] 7JTTEL, K. A. VON (1881/85) Handbuch der Palaeontologie, vol. 2, 893 pp., 1109 text figs., many tables, Miinchen und Leipzig, R. Olden­burg. Stone City Peleoypoda Plate 3 The flat surface formed by the basal conglomerate of the Wheelock member of the Cook Mountain formation seen obliquely from above. Each knob is a small boulder composed of fossiliferous glauconlte arenite, freed from the surrounding matrix but still firmly attached at its bottom. Note the bedding within the vari­ous boulders, indicated by fossiliferous streaks. This bedding stands at various attitudes In the boulders and may even be vertical. The cannon-ball concretions of bed (I) of the Stone City beds at the bluff. The surface has been wetted down. Sto e City Pelecypoda Plate 4 FtGURES­1-4. 5-7. 8,9,12-14. 10,11. 15-17. 18-20. 21-25. 26--30. Plate 4 PAGE Nucu/,a ( N ucula) mauricensis Harris ________________ ----------------------------___ ---------------------------------------43 1,2. Outside and inside views of a left valve, a topotype, x21h, from the Cook Mountain formation at Orell's Crossing of Elm Creek; bluff, 20 feet high, on right bank at first large horseshoe bend upstream from bridge and about 700 feet from Giddings-Manheim road, 5.6 miles by road west-northwest from Giddings courthouse, west-central Lee County, Texas; Bur. Econ. Geology locality no. 144-T-5. 3,4. Outside and inside views of a right valve, x4, from bed (s) of the Stone City beds at Stone City Bluff. Nucu/,a (Nucula) smithvi,llensis Stenzel & Twining, n.sp., x4 ------------------------------------------44 5. Outside view of a right valve, a paratype. 6,7. Inside and outside views of a right valve, holotype. From the Viesca member of the Weches formation of the bluff on right hank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. Calorhadia ( Calorhadia) compsa (Gabb) ·-----------------------------------------------------------------________ __ 47 8,9,12. Inside and two outside views of a right valve, xl1h except for fig. 12 which is x21h. 13,14. Inside and outside views of a left valve, xl:th. Both are topotypes from bed (u) of the Stone City beds at Stone City Bluff. The low crater-like object on figs. 9 and 12 is the attached base of an alcyonarian coral, probably of the order Gorgonacea. The track-like imprints were made by bryozoan branch colonies attached to the shell. Calorhadia (Litorhadia?) bastropensis (Harris), x21h -------------------------------------------------------51 Outside and inside views of a right valve, the holotype, probably from the Viesca member of the Weches formation of the bluff on the right hank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2; Texas Geol. Survey coll. no. 221, station no. 12. Calorhadia (Calorhadia) praecompsa Stenzel & Krause, n.sp., xl% and 2% --------------. 49 Inside and two outside views of a left valve, the holotype, from the Viesca member of the Weches formation at the bluff on the right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. Of the two attached objects one is a very young oyster, probably Cubitostrea smithvillensis (Harris) , the other a hexacoral. Calorhadia (Litorhadia) petropolitana Stenzel & Krause, n.sp., xl%, 2%, and 21h--------50 Two outside views of a left valve, the holotype, and inside view of a right valve, a paratype, from bed (c) of the Stone City beds at Stone City Bluff. Calorhadia (Litorhadia?) evanescentior Stenzel & Krause, n.sp.______________________________________ 52 21,22. Outside and inside views of a right valve, a paratype, x2%. 23. Outside view of a right valve, the holotype, xl%. 24,25. Outside and inside views of a left valve, a paratype, x21h. FrGm the Stone City beds at Stone City Bluff; the first two specimens are from bed (s). Orthoyoldia psammotaea,Dall, xl% ---------------------------------------------------------------------------------------54 26,27. Outside and inside views of a right valve from bed (u) of the Stone City beds at Stone City Bluff. 28,29. Outside and inside views of a left valve, from the Stone City beds of J. D. Creek, Bastrop County, Texas, J. T. Twining collector. 30. Outside view of a left valve, from bed (s) of the Stone City beds at Stone City Bluff. Bureau of Economic Geology, The University of Texas Plate 5 FIGURES-PAGE 1-4. Arca (Arca) petropolitana Stenzel &Krause, n.sp., x2% and l %· -------~·----·---·---·-··---·--------56 Dorsal, inside, outside, and inside views of the single left valve, the monotype, from bed (£) of the Stone City beds at Stone City Bluff. Figure 4 shows the valve before damage and the true original valve outline. 5-10. Barbatia (Barbatia) uxorispalmeri Stenzel & Krause, n.sp., xl%---·--------------------·--·-·--------5.8 5,6. Inside and outside views of a right valve, the holotype. 7,8. Inside and outside views of a right valve, a para-type. 9,10. Outside and inside views of a left valve, a paratype. All from bed (s) of the Stone City beds at Stone City Bluff. 11-13. Glycymeris trigonella Conrad, x4·-----------·-···--·-------·-····-···------·--------··--·-··-····-·········--·····--·-····-··· 60 Outside and two inside views of three topotype valves, from the ·Gosport sand of Claiborne Bluff, Monroe County, Alabama. 14-16. Glycymeris wautubbeana Harris, x4..·-·-·-····-·----·--·-··-·-·-------·---·-·-··------···-----····-···············--------60 Outside view of a valve, a topotype, and outside and inside views of another valve, also a topotype, from the Archusa marl member of the Cook Mountain formation (or Wautubbee formation) of the railroad cut about 1 mile north of the . depot at W autubbee or about 0.4 mile north of the overpass of U.S. Highway 11 (Meridian-Laurel road) over the Southern Railroad, northwestern Clarke County, Mississippi. 17-18. Glycymeris sabinensis Harris, x4·-·-·-·····-·····----··-----···--·····--·-··------------------------------------~------· -·· ·--60 Inside and outside views of two topotype valves, from the Cook Mountain formation on the right bank of the Sabine River, on the long west-east reach of the river opposite section 35, T. 5 N., R. 13 W., Sabine Parish, Louisiana, 0.4 mile northwest of Crane Pond and 1.4 miles air-line distance northwest of U. S. Geological Survey bench mark 164 at the road fork known as Columbus, Louisiana, in eastern Sabine County, Texas (Veatch's locality 22); Bur. Econ. Geology locality no. 201-T-20. 19-22. Glycymeris petropolitana Stenzel & Twining, n.sp., x4·--·-·------------·-·--·---·--·------·------------------60 19,22. Outside and inside views of a valve, the holotype. 20,21. Outside and inside views of a valve, a paratype. Both from bed ( w) of the Stone City beds at Stone City Bluff. Stone City Pelecypoda Plate 5 Plate 6 Stone City Pelecypoda Plate 6 FIG~RES­ PACE 1-4. Pachecoa (Pachecoa) cainei Harris, x--L . . . ___ .. ... _ 63 1,2. Inside and outside vie,,s of a right valve. 3,4. Outside and inside ,-iews of another right vah·e. Both from the :\leBean formation of the fir:-;t deep road cut at Rattle­snake Hill on the new Orangehuq!-Columhia highway (U. S. Hidn,av 31), immediately south of Turkey Hill Bran('h and -1.0:2 miles b~· roa~f north of the railroad depot in ea~tern Orangelmrg or 1.91 miles b~· road north of the highwa~ f01~k of U. S. Highway 178 By-pass (Orang~burg­North road) and U. ~. Highway 21, Orangeburg County, South Carolina. Both vah·es are silicified. 5,6. Pachecoa (Pachecoa) pulchra (Gabb), x4 _ ·-------·----___________ ______ --·· ___..... . 65 Outside and inside views of a left valve, topotype, from bed (u) of the Stone City heds at Stone City BlufT. 7-9. Pachecoa (Pachecoa) smithvillensis Stenzel & Twining, n.sp., x4 677. Dorsal view of complete she11, a paratype. 8,9. Inside and out~ide views of a right valve, the holotype. From the Viesca member of the Werhes formation from a hlufT on the right bank of the Colorado River in Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71 (Bastrop-Smitln·ille road), built in 1950; Bur. E<'on. Geology locality no. 11-T-2. 10,11. Pachecoa (Pachecoa) adamsi (Palmer), x-t ______ ---·-·------··--·. _____ ........... _ 68 Inside and outside views of a right vah·e, a topotype, from the upper Queen City formation at the mouth of Gazlev Creek into Colorado RiYer, at Smithville, Bastrop County, Texas, up~tream from the new bridge of State Highway 71, built in 1950: Bur. Econ. Geology locality no. l l-T-38. 12-14. Pachecoa (Pachecoa) catonis Stenzel &Twining, n.sp. _____ ____ _. __.. . .. ..... __ __ ... _ _... ..... . 68 12,13. Inside and outside views of a right vah·e, the holotype, x-L 14. Enlarged detail of sculpture from holotype, x71;~. From the uppermost part of the Tallahatta formation at Caton·s Bluff, a low bluff on the left bank of the Conecuh River, about 1.000 feet north of the Country Club Road. that i~, the road leading from Andalusia past the country club to Pre:'twood Bridge, :-1ection 1-t T. -! N.• R. 15 E., about 0.2 mile from Prestwood Bridge and about 3 miles ,,-e~t-northwest of Andalusia, Covington County. Alabama. 15,16,21,22. Nanohalus cossmanni (Dal}), x-1 _ .. ..... ----·--____ . ___ ____ _........ _... . . -·-······-·· -··· --· 72 15,16. Outside and inside views of a left vah·e, a topotype. 21,22. Inside and outside Yiews of another left valve, a topotype. From the Gosport sand at Claiborne Bluff, :\lonroe County, Alabama. 17-20. Pachecoa (Pachecoa) sabinica (Harris), x4 ___ ___ _ ___ ___. _ 66 17,18. Outside and inside views of a left vah-e from bed (d l of the Stone City beds at Stone City Bluff. 19,20. Inside and outside ,:iew~ of a right vah-e, a topotype. From the Stone City beds on the right hank of the Sahinf> RiYer at the west end of the long west-east reach of the river, opposite ~ef'tion .35, T. 5 N., R. 13 W.. in Sabine Parish, Louisiana. 0.65 mile northwest of Crane Pond and 1.8 miles air-line distance northwe~t of U. S. Geolou:i<'al SurYey bench mark 16-± at the road fork known as Columbus, Louisiana. This is localitv 21 of Veatch (1902. p. 129. pl. :13 l: Bur. Econ. Geology locality no. 20i-T-15, in Sabine County. Texa:'. The holes in the shells figured in figs. 8,9,21, and 22 are borings made by naticoid snails, probably Polinices aratus (Gabb) . Plate 7 FIGURES- PAGE 1. Mauricia leonia Stenzel & Krause, n.sp., xl1h------------------------------------------------------------------------77 Outside view of a right valve, the monotype, from a glauconitic shell hreccia with clay-ironstone matrix in the Mount Tabor member of the Cook Mountain formation on the Middleton­Sulphur Springs School county road, right hank of a dry north-flowing branch, being a right tributary of Boggy Creek, in the woods about 200 feet below a fence and tank and about 0.55 mile north of the county road, in the south corner of F. C. Wilson 100-acre tract, A. Richardson survey, Leon County, Texas; Bur. Econ. Geology locality no. 145-T-80. 2-8. M auricia houstonia Harris, xl1h ---------------------------------------------------------------------------------------------75 2,7,8. Frontal, right lateral, and dorsal views of a shell filled with glauconitic marl, in part decorticated, from Stone City Bluff. 3-5. Frontal, right lateral, and dorsal views of a shell filled with glauconitic marl, the monotype, from the Hurricane lentil at the base of the Landrum member of the Cook Mountain formation of the bluff in the woods on right bank of Hurricane or Three-Mile Bayou, at a large meander, convex to the north, 200 to 500 feet southeast of the county road from Crockett to San Pedro Chapel (Mail Route 1 or old Crockett-Rusk road) about 2,100 to 2,600 feet air-line distance northeast of the county road bridge (BR 303) over the bayou, which is 3.35 miles by road from the courthouse in Crockett, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-2. 6. Left lateral view of a shell filled with glauconitic marl, in part decorticated, from Stone City Bluff. 9. Atrina cawcawensis (Harris), xl%--------------------------------~-------------------------------------------------------78 Right lateral view of a shell filled wiih glauconitic marl, from bed ( w) of the Stone City beds at Stone City Bluff. 10--13. Pteria limula (Conrad) , xL________________ ---------------------------------------------------------------------------------------82 10,11. Dorsal and outside views of a right valve, a topotype, from the Gosport sand at Oaiborne Bluff, Monroe County, Alabama. 12,13. Inside and outside views of a right valve, from the Gosport sand of Little Stave Creek near Jackson, Clarke County, Alabama. 14-15. Pteria ( Pteria) petropolitana Stenzel &Twining, n.sp., x2% ---------------------------------------------81 Inside and outside views of a right valve, the holotype, from bed ( w) of the Stone City beds at Stone City Bluff. 16-21. E bumeopecten scintillatus Conrad, x4. _----------------------------------------------------------------------------------84 16-19. Outside and inside views of a left valve and a right valve, both topotypes, from the Moodys Branch marl of a bluff on the south or left hank of Garland's Creek, about 3.5 miles air-line distance northeast of Shubuta 0.2 mile east of bridge over the creek, in southwest comer of SE 1A, of SW % of section 21, T. 1 N., R. 16 E., Oarke County, Mississippi. 20,21. Inside and outside views of a right valve, from bed ( u) of the Stone City beds at Stone City Bluff. See also Pl. 10, fig. 8. Plate 7 Stone City Pelecypoda ,, .,,,..,. , ... ........ ______............ I I I Stone City Pelecypoda Plate 8 Plate 8 FIGURES- PAGE 1,2. Lima (Limatulella) petropolitana Stenzel & Twining, n.sp., x21h.................................. 88 Two views of the spread valves of the monotype in a matrix of glauconite marl, from bed ( w) of the Stone City beds at Stone City Bluff. 3,6,7 ,9-12. Anomia ephippioides Gabb, xl1h--------·-----------------------·----------------·--------------···-·------------··---······ 98 3,6,9. Outside views of three left valves, of which two, namely 6 and 9, have excellent allomorphic sculpture copied fro·m a substratum of Veneri­cardia ( V enericor) planicosta densata (Conrad) , from bed ( s) . Note the byssus plug near the center of fig. 3. 7,10. Calcified byssus plugs attached to the interior of a fragment of the shell of Aturia ( Brazaturia) brazoensis Stenzel (?) (fig. 7) from bed (s) and to the interior of a right valve of Venericardia (Venericor) planicosta densata (Conrad) . 11,12. Outside and inside views of a left valve, overgrown with a bryozoan colony. All topotypes from the Stone City beds of Stone City Bluff. 4,5. Lima (Ctenoides) bastropensis Stenzel & Twining, n.sp., x21h .---------·--·---------------·-·····------90 Outside and inside views of a left valve, the monotype, from the Cook Mountain formation of a bluff on left bank of Pinoak Creek next to a county road leading northward to Center Union School, 800 feet north of a right-angle turn of the Smithville-Winchester road (Farm Road 1870), 0.5 mile south of Center Union School and 0.6 mile southwest of Center Union Church, 4.5 miles by road northwest of Win­chester, eastern Bastrop County, Texas; Bur. Econ. Geology locality no. ll-T-70. 8. Anomia jugosa Conrad, x 1..__ .................................................................. _................. . ... ... ..... . ... 10I Outside view of a left valve, the monotype, from the "White limestone of S. Carolina" (Conrad, 1843, p. 310; 1846a, p. 22, pl. 1, fig. 15, not fig. 14 as stated in text), collection of Academy of Natural Sciences of Philadelphia. 13. Lima ( Limatulella) smithvillensis Stenzel & Twining, n.sp., x21h ··---------·············--·------·-· 88 Outside view of a left valve, the monotype, partly decorticated, from the Viesca mem·ber of the Weches formation of a bluff on the right bank of the Colorado River in Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71 (Bastrop­Smithville road), built in 1950; Bur. Econ. Geology locality no.11-T-2. Plate 9 FIGURES- PAGE 1,2. Anomia ephippioides Gabb, xl1h--------------------------·-··--··-······--···· ............... ............................ 98 Inside and outside views of a right valve, a topotype, from the Stone City beds at Stone City Bluff. 3,4. Diplodonta (Diplodonta) petropolitana Stenzel, n.sp., x4 ..................................................... 117 Inside and outside views of a left valve, the holotype, from 'bed (s) of the Stone City beds at Stone City Bluff. 5,7-11. Cubitostrea (Cubitostrea) divaricata (Lea), xl1h--····--·--··-·-···-·······················-···················· 92 5. Outside view of a small left valve with a large attachment scar. 7,8. Inside and outside views of a right valve. 9. Outside view of another right valve. 10,11. Outside and inside views of a fully grown left valve. All topotypes from the Cook Mountain formation (or upper Lisbon formation) of the road cut near the bottom of the road leading to the present upper landing at Claiborne, Monroe County, Alabama. 6. Cubitostrea ( Cubitostrea) cubitus (Deshayes), xl1h--·-··············--·--············-···--·--·--·-··········· 91 Outside view of a left valve, from the Auversian of Crepy en Valois, Departement Oise, France; col­lection Chantegrain of Maintenon, Bur. Econ. GeolQgy coll. no. 12363. Stone City Pelecypoda Plate 9 Stone City Pelecypoda Plate 10 ,-../ ,.. \ I I I '•/ 1... '·,~, \ Plate 10 FICURES-PACE 1-7. Cubitostrea (Cubitostrea) sanctiaugustini Stenzel & Twining, n.sp., xl%...................... 93 1,2. Outside and inside views of a left valve, a paratype. 3. Outside view of a left valve, the holotype. 4-7. Inside and outside views of two right valves, paratypes. From the Tyus member of the Weches formation in the excavation at the east side of the intersection of South Liberty and East Planters Streets, 3 blocks east and 3 blocks south of the southeast corner of the courthouse square, 0.4 mile air-line distance southeast of courthouse in the town of San Augustine, San Augustine County, Texas; Bur. Econ. Geology locality no. 202..T-8. The attachment scar of the left valve, figs. I and 2, is from a shell of the gastropod Ectinochilus texanus planus (Harris) = Ectinochilus texanum cherokense Palmer, 1944. The attachment scar of the left valve, fig. 3, is ·probably from a shell of a Dentalium. The bulb-like inflated early part of the right valve, figs. 6 and 7, is caused by the attachment of the left valve to a convex substrate, probably an inflated gastropod shell, and is therefore an allomorphic sculpture imposed by the substrate. 8. Eburneopecten scintillatus Conrad, x4.................................................................................... 84 Outside view of a left valve from bed ( u) of the Stone City beds at Stone City Bluff. Plate 11 FIGURES- PAGE 1-4,13,14. Venericardia (Venericor) planicosta densata (Conrad), xL.-----------------------------·--···------·-·-· 103 1,2. Outside and inside views of a right valve, from bed (u) of the Stone City beds at Stone City Bluff. 4. Inside view of a left valve, from the Stone City beds at Stone City Bluff. These two valves, and the one of Pl. 8, fig. 10, are all topotypes of "Venericardia mooreana" Conrad, 1867. 3,13,14. Two outside and one inside view of two right and one left valve, all topotypes, from the Cook Mountain formation (or upper Lisbon formation) of the base of the bluff beneath the bridge at Claiborne, Monroe County, Alabama. These are all topotypes of "Cardita densata" Conrad, 1845. 5-12. Cubitostrea (Cubitostrea) petropolitana Stenzel & Twining, n.sp., xl%..------····--------94 5,6,11,12. Inside and outside views of two right valves, paratypes. 7,8. Outside and inside views of a left valve, the holotype. 9,10. Outside views of the left side and the right side of a complete shell, a paratype, showing the difference in the respective sizes of the two valves. All from the Stone City beds at Stone City Bluff. The right valve figured in figs. 11and12 is from bed (s). The figs. 7 and 8 show a cluster of 3 left valves and some spat grown on a right valve of Anomia ephippioides Gabb. The figs. 9 and 10 show 4 shells of this .oyster species grown on a shell of the gastropod Pseudoliva carinata Gabb; the right valves in fig. 10 show there£ore allomorphic sculpture in form of a bulb-like convexity of the early part of the valve; this allomorphic sculpture is a reflection of the convex shell of the gastropod. Stone City Pelecypoda Plate 11 11 ........, .... _ .... _ Stone City Pelecypoda Plate 12 Plate 12 FIGUllES-PAGE 1,2. Abra (Abra) petro'/)Olitana Stenzel, n.sp., x4 ------~------------------------------------------------------------____ 119 Inside and outside views of a right valve, the monotype, from bed (s) of the Stone City beds at Stone City Bluff. 3-10. Crassostrea /rionis (Harris) --------------------------------------------------------------------------------------------------. 95 3-6. Outside and inside views of two left valves, x1h. 8,9. Inside and outside views of a right valve, xl. All from the Stone City beds at Stone City Bluff. 7,10. Outside views of two right valves, xi, from the Stone City beds or the Cook Mountain formation on ""road below Pleasanton, Atascog County, Texas"; Bur. Econ. Geology locality no. 7-T-l and catalog no. 9323. Bureau of Economic Geology, The University of Texas Plate 13 FIGURES- PAGE 1-9. Venericardia (Claibornicardia) alticostata (Conrad), xL_______ ·-----------·---·-···-···················· 107 1,2. Inside and outside views of a left valve. 3-8. Outside and inside views of 3 right valves. 9. Frontal view of a complete shell. All are topotypes from the Gosport sand of Claiborne Bluff, Monroe County, Alabama. The right valve shown in figs. -5 and 6 is the only valve available to us that seems to be somewhat intermediate to V enericardia ( Claibornicardia) sillimani Lea. 10,11. Sinodia (Sinodia) eocaenica Stenzel & Krause, n.sp., xllh--------·---·--··--·······-··-····· ............ 160 Inside and outside views of a right valve, the monotype, from Stone City Bluff. Stone City Pelecypoda Plate 13 Stone C ity Pelecypoda Plate 14 Plate 14 FIGURES- PAGE 1-4. Y enericardia (Claibornicardia) sillimani Lea, xL----------------------------------------···-···-·········-····· 110 Outside and inside views of a right and a left valve, topotypes, from the Gosport sand of Claiborne Bluff, Monroe County, Alabama. 5. Y enericardia (Claibomicardia) a/,ticostata (Conrad), xL..·--··--····------------····----------------------107 · Dorsal view of a complete shell, same as Pl. 13, fig. 9, a topotype, from the Gosport sand of Claiborne Bluff, Monroe County, Alabama. On the bottom left of this figure the shell has a worm boring doubling hack on itself. This is a boring made by an annelid worm, probably of the genus Polydora. 6-11. Yenericardia (Claibomicardia) trapaquara Harris..-----------------·-----------·--------------··--·----·-··---114 6. Inside view of a left valve, x21h, from bed (s) of the Stone City beds at Stone City Bluff. 7,8. Outside and inside views of a right valve, the holotype, x4, from the Stone City beds in Town Branch of Cedar Creek, 200 yards north of the Brazos-Robertson County line, which is on the Old Spanish Road, in southeast corner of the E.L.R. Wheelock survey, Robertson County, Texas; old Texas Geol. Survey locality no. 46a and catalog no. 256; Bur. Econ. Geology locality no. 197-T-3. 9,10. Outside and inside views of a right valve, x21h, from the Stone City beds at Stone City Bluff. 11. Antero-ventral fragment of a left valve, x21h, showing sculpture unaffected by wear, from bed (s) of the Stone City beds at Stone City Bluff. Bureau of Economic Geology, The University of Texas Plate 15 FIGURES-pAGE 1-4. Venericardia (Claibornicardia) complexicosta Meyer & Aldrich, x21h---------------------------111 Outside and inside views of two right valves, from the Archusa marl memb.er of the Cook Mountain formation (or Wautubbee formation) of the road shoulder and ditch on the north side of the public gravel road connecting Decatur with Conehatta, 7 .8 miles by road west of the intersection with State Highway 15 (Newton-Decatur road) at Decatur and 0.4 mile west of a crossroads, in the southeast corner of SW 114 of NE 1t4 of section 3, T. 7 N., R. 10 E., Newton County, Mississippi. The anterior part of the hinge of the smaller valve is damaged. 5,6,9,10. Tellina (Eurytellina) mooreana Gabb, xl1h------------------------------------------------------------------------121 Outside and inside views of two left valves, to po types, from bed ( w) and bed (s), respectively, of the Stone City beds at Stone City Bluff. 7,8. Tellina ( Eurytellina) papyria Conrad, xl% -----------------------------------------------------------------------122 Outside and inside views of a right valve, a topotype, from the Cook Mountain formation (or upper Lisbon formation) about 10 feet above the V enericardia densata bed at the base of the bluff be­neath the bridge at Claiborne, Monroe County, Alabama. 11-14. Kymatox lapidosus (Conrad), xl%------------------------------------------------------------------------------------------126 11,12. Frontal and right lateral views of the internal mold of a shell from Con-rad's type lot. 13,14. Right lateral and dorsal views of the internal mold of a shell, -Conrad's monotype. From the -Santee limestone or possibly the McBean formation on the right or south bank of the Santee River at Vance's Ferry north of the railroad depot at the town of Vance, eastern Orangeburg County, South Carolina; collection of Academy of Natural Sciences of Philadelphia. 15,16. Kymatox praelapidosus Stenzel & Krause, n.sp., xl1h-------------------------------------------------------····· 132 Dorsal and left lateral views of a complete shell, the holotype, from the Stone City beds at Stone City Bluff. Plate 15 Stone City Pelecypoda \ (' City Pelecypoda Plate 16 Stone · Plate 16 l4'IGURES- PAGE 1-3. Kymatox papyrius (Conrad) , xL_________________________ ------·-·----------·-·····-···-­____ .·--------·-···---------·----·--·· 130 1,2. Inside and outside views of a left valve, the lectoholotype. 3. Inside view of a left valve, the lectoparatype. Both from the Gosport sand of Claiborne Bluff, Monroe County, Ala­ bama; Conrad's types in the collection of the Academy of Natural Sciences of Philadelphia. '-6,15,16. Katherinella smithvillensis Stenzel & Krause, n.sp., xl1h ·--·····-···--····-···-----------····--·-···--·-··-­ 135 4,5. Outside and inside views of a right valve, the holotype, from the Viesca member of the Weches formation of the bluff on the right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71 (Smithville-Bastrop road), built in 1950; Bur. Econ. Geology loeality no. 11-T-2. 6. Dorsal view of a complete shell, a paratype, from bed (h) of the Stone City beds at Stone City Bluff. 15,16. Outside and inside views of a right valve, a paratype. From bed (c) of the Stone City beds at Stone City Bluff. 7-10. Katherinella trinitatis Stenzel & Krause, n.sp., xl1h ----------------------------··------------------------------137 7,8. Inside and outside views of a left valve, the holotype. 9,10. Outside and inside views of a right valve, a paratype. From the Stone City beds of a bluff on the left bank of the Trinity River at a sharp but obtuse bend, 0.85 mile air-line distance north of the abandoned Alabama Ferry, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-36. 11-14. KatherineUa? texitrina Stenzel & Krause, n. sp., xl1h ------·-···----------······-----------------···-····· ·-·· 138 11,12. Inside and outside views of a left valve, a paratype. 13,14. Outside and inside views of a right valve, a paratype. From the Stone City beds of a bluff on the left hank of the Trinity River at a sharp hut obtuse bend, 0.85 mile air-line distance north of the abandoned Alabama Ferry, Houston County, Texas; Bur. Econ. Geology locality no. 113-T -36. Bureau of Economic Geology, The University of Texas Plate 17 PAGE FIGURES­ 1,2. Pitar (Calpitaria) parisiensis (Deshayes), xl%..-------------------------­---------------------------------------­Outside and inside views of a right valve, 142 from the Lutetian of Houdan, Departement Seine et Oise, France; collection Chantegrain of Maintenon, Bur. Econ. Geology coll. no. 12113. 3-8. Pitar (Ca/,pitaria) petropolitanus Stenzel & Krause, n.sp., xl%­----------------------------------------­ 143 3,4. Inside and outside views of a left valve, a paratype. 5,6. Inside and outside views of a left valve, the holotype, Bur. Econ. Geology catalog no. 20186, collector WK [William Kennedy] labeled originally "Cythera/ texacola/ var. tornadonis/ Sta Moseley Ferry/" in Texas Geol. Survey collection. 7,8. Outside and inside views of a right valve, a para type, from bed ( u) . All from the Stone City beds at Stone City Bluff. 9-14. Pitar ( Ca/,pitaria) tornadonis (Harris) , xl1h.----------------------------------------------------------------------­ 148 9,10,13,14. Outside and inside views of two right valves, from the Cook Mountain formation of the right bank of the Colorado River just east of the Bastrop-Fayette County line at the mouth of a small tributary having several waterfalls over clay-ironstone ledges, 1,650 feet southeast of a sharp acute bend in public gravel road leading to Smith­ ville-La Grange road (State Highway 71) , some 4 miles east of Smith­ ville, Bastrop County, Texas, near the abandoned Shipp's Ford; Bur. Econ. Geology locality no. ll-T-29. 11,12. Right lateral and dorsal views of a complete shell, the holotype, from the Hurricane lentil at the base of the Landrum member of the Cook Mountain formation of probably the bluff in the woods on the right bank of Hurricane or Three-Mile Bayou, at a large meander, convex to the north, 200 to 500 feet southeast of the county road from Crockett to San Pedro Chapel (Mail Route 1 or old Crockett-Rusk road) about 2,100 to 2,600 feet air-line distance northeast of the county road bridge (BR 303) over the bayou, which is 3.35 miles by road from the court­ house in Crockett, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-2 and catalog no. 20184. Stone City Pelecypoda Plate 17 4 9 10 Plate 18 Stone City Pelecypoda 14 15 Plate 18 FIGUBE.T-PAGE 1,2. Pitar (Calpitaria) texibrazus Stenzel & Krause, n.sp., xl.................................................. 147 Inside and outside views of a left valve, the monotype, from bed ( w) of the Stone City beds at Stone City Bluff. 3,4. Pitar (Calpitaria) texacola (Harris), xl1h and 1------------------------------------------------------------···· 145 Hinge and outside view of a left valve, the holotype, from the Tyus member of the Weches formation of the vicinity of Berryman's home place, 3.88 miles air-line distance northeast of Alto, at B.M. 406, Cherokee County, Texas; Texas Geol. Survey catalog no. 382, labeled "382/Cytherea texacola/n.sp./Sta.58 Kimble hdt./Houston Co./Collector Kennedy." 5,6. Rhabdopitaria texangelina Stenzel & Krause, n.sp., xl1h-------------------·-------------------------·····--·· 158 Outside and inside views of a right valve, the monotype, from the Stone City beds of the highway borrow pit at the edge of the river flood plain about 300 feet east of U. S. Highway 59 (Lufkin­Nacogdoches road), 0.83 mile south of the Angelina River or 2.5 miles north of the school at Redland, north-central Angelina County, Texas; Bur. Econ. Geology locality no. 3-T-18. 7-10. Rhabdopitaria astartoides (Julia Gardner), xl1h--················-·-····--·-······--·-··········--·········-····-155 Outside and inside views of a left and a right valve, from the Stone City beds of a bluff on the left bank of the Trinity River at a sharp but obtuse bend, 0.85 mile air-line distance north of the abandoned Alabama Ferry, Houst~n County, Texas; Bur. Econ. Geology locality no. 113-T-36. 11-12. Rhabdopitaria subcrassa (Lea), xl% .......... -·--··········--·········-······-············-··-----·····-··-·····--·--·--157 Inside and outside views of a left valve, a topotype, from the Gosport sand of Claiborne Bluff, Monroe County, Alabama. 13. Pholadomya leonensis Stenzel & Twining, n.sp., x4............................................................ 164 Enlarged detail of sculpture on posterior half of a shell, the monotype, from the Viesca member of the Weches formation in the north ditch of the old, abandoned Concord-Centerville county road, 0.6 mile southeast of site of dismantled Robbins depot; in south comer of J .M.Powell 100-acre tract, in south corner of R.M.Tyus survey, Leon County, Texas; Bur. Econ. Geology locality no. 145-T-l. 14. PholaJ,omya harrisi Gardner, x4 ---------------------···-·. .... .... ···············-···-······------------·-··············· 162 Enlarged detail of sculpture on posterior half of a shell, from the Cook Mountain formation in the creek bed, 2 miles west of Crockett, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-7; Texas Geol. Survey locality no. 253; Rio Bravo en Company collection. 15. PholaJ,omya petropolitana Stenzel & Twining, n.sp., x4 .... ·········-·-···-·-······························· 163 Enlarged detail of sculpture on posterior half of a shell, the holotype, from the Stone City beds at Stone City Bluff. Bureau of Economic Geology, The University of Texas Plate 19 FIGURES-PAGE 1-3. Pholadomya petropolitana Stenzel & Twining, n.sp., xl~--------·-···-----········--···-···················· Right lateral, dorsal, and left lateral views of a shell, the holotype, 168 from the Stone City beds at Stone City Bluff. Compare Pl. 18, fig. 15. 4,5. Pholadomya leonensis Stenzel & Twining, n.sp., xl~--·-----·-----····-·····-································-·· Dorsal and right lateral views of a shell, the monotype, 164 from the Viesca member of the Weches formation in the north ditch of the old, abandoned Concord-Centerville county road, 0.6 mile southeast of site of dismantled Robbins depot; in south corner of J.M.Powell 100-acre tract, in south corner of R.N.Tyus survey, Leon County, Texas; Bur. Econ. 'Geology locality no. 145-T-l. Compare Pl. 18, fig. 13. 6,7. Pholadomya harrisi Gardner, xl~------·----------------------------------------------1....................................... 162 Right lateral and dorsal views of a shell, from the Cook Mountain formation in the creek bed, 2 miles west of Crockett, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-7; Texas Geol. Survey locality no. 253; Rio Bravo Oil Company collection. Compare Pl. 18, fig. 14. 8-13. Caryocorbu/,a a/,abamiensis (Lea) ________________ -----­------------------------------------·--·----­-------·-·····-···--····· 165 8,9. Left~ateral and dorsal views of a complete shell, x4. 10-13. Outside and inside views of a left and a right valve, x2~. All topotypes from the Gosport sand of Claiborne Bluff, Monroe . County, Alabama. Plate 19 Stone City Pelecypoda Stone City Pelecypoda Plate 20 17 Plate 20 FIGURES- PAGE 1-3,9,10. Caryocorbu/.a alabamiensis (Lea), x4_________________________________________________ ·------------------------------------165 1,2. Outside and inside views of a left valve, a topotype. 3. Inside view of a right valve, a topotype. 9,10. Inside and outside views of a right valve, a topotype. From the Gosport sand of Claiborne Bluff, Monroe County, Alabama. 4-8,11,12,17. Caryocorbula deusseni Gardner, x4.__._______ ----------------------______ ----------------------------------------------166 4,5. Inside and outside views of a right valve, a topotype. 6-8. Dorsal, left lateral, and frontal views of a complete shell, a topotype. 11,12,17. Outside, inside, and oblique dorsal views of a left valve, a topotype. From the Viesca member of the Weches formation at the bluff on the right hank of the Colorado River at Smithville, ·Bastrop County, Texas, about 625 feet downstream from the new bridge of State Highway 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. 13-16,18-21. Caryocorbula deusseni Gardner, x4·--------------------------------------·--------------------------------------------166 13,14. Outside and inside views of a left valve. 18,19. Inside and outside views of a right valve. Both from bed ( w) . 15,16. Inside and outside views of a right valve. 20,21. Outside and inside views of a left valve. Both from bed ( s). All from the Stone City beds at Stone City Bluff. Bureau of Economic Geology, The University of Texas Plate 21 FIGURES- PAGE 1-10. N otocorbula texana (Gabb), x4_______________ "----------------------------------·-----------·-------"---------················ 170 1,2. Inside and outside views of a right valve, a topotype, from bed ( u) • 3. Outside view of a left valve, a to potype, from bed ( u) . 4-6. Oblique dorsal, outside, and inside views of a left valve, a topotype, from bed (s). 7-10. Inside and outside views of two right valves, topotypes, from bed (s). All from the Stone City beds at Stone City Bluff. 11-21. Vokesula smithvillensis smithvillensis (Harris), x4 .... -----------···-----------------·-····-······--·-····--····· 174 11,12. Outside and inside views of the left valve of the holotype. 13,14. Inside and outside views of the right valve of the holotype. 15-17. Anterior, dorsal, and left lateral views of a complete shell, a topotype. 18,19. Inside and outside views of a left valve, a topotype. 20,21. Inside and outside views of a right valve, a topotype. All from the Viesca member of the Weches formation at the bluff on the right bank of the Colorado River at Smithville, Bastrop County, Texas, about 625 feet downstream from the new bridge of State High.. way 71, built in 1950; Bur. Econ. Geology locality no. 11-T-2. 22-29. V okesula smithvillensis petropolitana Stenzel & Twining, n.s.sp., x4 ................. _.______________ 176 22,23. Inside and outside views of a right valve, a paratype, from bed (w J. 24,25. Inside and outside views of a left valve, a paratype, from bed ( w). 26-29. Inside and outside views of two right valves, paratypes, from bed (s). All from the Stone City beds at Stone City Bluff. Stone City Pelecypoda Pl ate 21 Stone City Pelecypoda Plate 22 Plate 22 FIGURES- PAGE 1-:6. Yokesula smithviUensis petropolitana Stenzel & Twining, n.s.sp., x4 -----------------------------176 1,2. Outside and inside views of a right valve, the holotype. 3,4. .Outside and inside views of a right valve, a paratype. 5,6. Outside and inside views of a left valve, a paratype. All from bed (u) of the Stone City beds at Stone City Bluff. 7-9. Pitar (Ca/,pitaria) texacola (Harris) , xl._________________________________________________________ ...___ ......___ .___ ... 145 7. Outside view of a right valve. 8,9. Inside views of a right and a left valve respectively. All from the Tyus member of the Weches formation from the rock flat over which a left tributary to Murchison Creek flows southward, 0.1 mile north of Farm Road 228 ('Grapeland-Percilla road) and 0.67 mile air­ l_ine distance due west of the post office in Percilla, northwestern Houston . County, Texas; Bur. Econ. Geology locality no. 113-T-37. 10,11. TeUina (Moerella) petropolitana Stenzel & Krause, n.sp., xl% --------····-··-····-· ____--·------·-·· 123 Outside and inside views of a right valve, the monotype, from bed (s) of the Stone City beds at Stone City Bluff. 12-14. Pitar (Pitar) tumens (Gmelin) , xl_________________________________ .__________..__________________________ ._________ .. _. __ 140 12,13. Inside and outside views of a right valve. 14. Inside view of the left valve of the same individual. A recent shell from Guinea, French West Africa; Bur. Econ. Geology coll. no. 2887. 15,16. Katheri.neUa? texitri.na Stenzel & Krause, n.sp., xl1h ------------------------------------------·····----···-·-·· 138 Inside and outside views of a left valve, the holotype. From the Stone City beds of the bluff on the left hank of the Trinity River at a sharp hut obtuse bend, 0.85 mile air-line distance north of the abandoned·Alabama Ferry, Houston County, Texas; Bur. Econ. Geology locality no. 113-T-36. Index A. barbata: 57 abbreviata, Trinacria decisa: 69 abbreviated section: 21 Abra: 7, 28, 29 alba: 28, 30, 31 Leach: 118-120 nitida: 33 prismatica : 33 tenuis: 118 Abra (Abra) nitens: 119 perovata: 119 petropolitana: 8, 41, 118, 119-120, 204 Academy of Natural Sciences of Philadelphia: 11, 40,41,49,6~93, 101, 104, 109, 111, 113, 115, 122, 127, 128, 132, 154, 172, 201,208,209 Academy of Sciences in Berlin: 11 acala, Leda : 50 acuticosta, Venericardia ( Claibornicardia) : 106, 107, Ill Adams, Henry & Arthur: 83, 90 adamsi, Pachecoa: 68, 199 Adanson, : 140, 141 Adapedontida: 165-176 Adkins, W. S.: 74 Adriatric Sea: 170 aeration : 32 Aerial Photographic & Engineering Service: 10 Africa: 59,86,97, 107, 116, 140, 170,215 Popenguine, SCnegal: 107 Agassiz, : 83 agricola: 147 Agricultural and Mechanical College of Texas: 42 ( Agriopoma) amichel, Callocardia: 137 tornadonis, Callocardia: 148 Alabama: 8, 14, 43, 45, 55, 72, 83, 84, 85, 92, 95, 107' 108, 110, 125, 126, 130, 153, 162, 165, 168, 178 Andalusia: 199 Claiborne: 14, 54, 103, 108, 112, 127, 128, 131, 146, 204 Claiborne Bluff: 45, 48, 58, 113, 119, 122, 127, 128, 165, 179, 198, 199, 200, 202, 206, 207, 208, 209, 211, 212, 213 Clarke County: 39, 46, 50, 200 Conecuh County: 39, 106 Covington County: 68, 199 Dale County: 90 Hatchetigbee Bluff: 85 Jackson : 200 Lisbon: 113 Monroe County: 46, 55, 60, 64, 69, 70, 71, 82, 93, 97, 101, 104, 105, 106, 109, 111, 117, 126, 132, 138, 153, 155, 157 Oakhill : 177 Oak Hill P.0.: 177 Washington County: 56, 107, 117 Wilcox County: 177 W oodbluff: 46, 50 Wood's Bluff: 48, 100, 174 Alabama Ferry, Houston County: 51, 79, 115, 137, 138, 140, 152, 153, 155, 156, 157, 158, 162, 209, 211, 215 Alabama River: 54, 55, 71, 84, 93, 103, 104, 109, 111, 114, 126, 132, 165 alabamensis, Ostrea : 115 alabamiensis: 175 Caryocorbula: 165, 168,212,213 Corbula: 165, 166, 168 ( Cuneocorbula) : 168 Crassostrea : 97 frionis, Ostrea : 95 Ostrea: 95 alba, Abra: · 28, 30, 31 Lima: 86 Albian: 75 Upper: 74 albida B., D., &D.: 169 albirupina, Calorhadia (Litorhadia?) : 52 Litorhadia: 51 alcyonarian coral: 197 Aldrich, T. H.: 8, 15, 45, 46, 68, 82, 90, 91, 99, 100, 106, 107, 108, 110, 111, 112, 113, 126, 128, 154, 162, 164, 11s, 179, ·208 Aldrich collection: 167 aldrichiana, Calorhadia ( Litorhadia) : 50 Yoldia: 50 aldrichi, Corbula: 174 smithvillensis, Corbula: 173, 174 Algeria: 43 allomorphic sculpture: 9, 98, 99, 101, 201, 203, 204 (Aloidis) texana, Corbula: 171 Alphonso d' Aguirra & Gadea Comes de Yoldi: 89 alta, Crassatella: 126, 128 alticosta, Cardita: 107 alticostata, Cardita: 104, 108, 109, 110 Venericardia: 106, 108, 109, 110 ( Claibornicardia) : 8, 9, 104, 105, 107-109, Ill, 112,206,207 alticostata stock: 114 alticostata-rotunda stock: 115 phylogenetic arrangement of: 113 Alto: 146, 147, 162, 163, 211 quadrangle: 147 Alum Bluff, Trinity River: 146 Alum Creek: 151 ameghinoi, Cubitostrea: 92 ameliae popenguinensis, Venericardia ( Baluchi· cardia) : 107 Ameodontida: 43-55 amichel, Callocardia ( Agriopoma) : 137 Crassostrea: 97 ammonite: 107 Amphidesrpa tenuis: 118 Amusiidae: 82-86 Amusium ( Pseudamussium) scintillatus: 84 anaerobic conditions: 32 analysis, statistical: 181-186 Andalusia, Covington County, Alabama: 68, 199 Anderson County: 117 Angelina County: 159, 172, 211 Angelina River: 159, 172, 211 annelid worms: 7, 29, 30, 207 Anomia: 9, 33, 34 ephippioides: 8,9,98-101, 115,201,202,204 ephippium: 97 hammetti: 100 jugosa: 101, 201 Linne: 97-101 Anomia­lisbonensis: 99, 100, 101 malinchae: 100 marylandica: 100 mcgeei: 100 navicelloides: 100 rufa: 100 8ellardsi: 100 Anomiicae: 41, 97-101 Anomiidae: 97-100 Aquia Creek, Virginia: 164 Aquia formation : 117, 164 aratus, Polinices: 199 Arca: 40 aurita: 71 ( cuculloides? ) ludoviciana : 58 glycymeris: 59 -like: 63, 64 Linne: 5~57 ludoviciana: 58 noae: 55 nucleus. Lin. : 43 sensu lato: ·70 S.S.: 56 Arca (Arca) hatchetigbeensis: 56 petropolitana: 8, 41, 56-:-57, 198 Arca ( Barbatia) cuculloides ludoviciana: 58 Archusa marl member: 112, 113, 178, 198, 208 Arcicae: 41, 5~59 Arcidae: 55-59, 66 Arcinae: 55-59 argenta, Pteria: 82 arp:entea, Atrina: 80 Con.: 78 Argovian: 7 4 arithmetic mean: 184, 185 arivechensis, Cardita : 108 Arkansas: 53, 84 Cow Creek : 62 Forrest City: 62 Jefferson County: 52 St. Francis County: 62, 70 Arkell, W. J.: 74 Army Map Service: 63 amoldi, Callocallista : 133 etheringtoni, Katherinella: 138 Katherinella: 133 Pitaria ( Katherinella) : 133 Arnold's ranch, Frio County: 39 Artemis trigona: 159 Astarte? : 127, 132 Conradi : 126 conradi: 127, 128 Astartidae: 156 astartoides, Callocardia: 151, 155, 156 Pitaria (Rhabdopitaria): 151, 155 Rhabdopitaria: 9, 139, 151, 152, 153, 154, 155­158, 211 Astoria formation : 138 Atascosa County: 7, 20, 34, 39, 96, 167, 205 athleta beds: 75 Atlanta road: 91 Atlantic Coastal Plain : 46, 68 Atlantic Coast of the United States: 53 Atlantic Ocean: 89 Atrina: 7, 29, 79, 80 argentea: 80 cawcawensis: 8, 27, 29, 78-80, 200 fragilis : 26 Gray: 78-80 jacksoniana: 79 vexillum: 78 attachment scar: 203 Aturia (Brazaturia) brazoensis: 99, 100 201 aurita, Arca: 71 ' Limo psis: 71 Trigonocoelia: 71 auritus, Pectunculus: 71 Austin: 41, 45, 49, 51, 52, 53, 57, 59, 61, 67, 68, 76, 77, 96, 115, 136, 139, 147, 148, 159, 161, 163, 165, 168 austinclarki, Nucula: 45 Australia: 86, 169 Auversian: 64, 83, 91, 92, 102, 202 Avicula: 81 tarentina: 80 Azores: 123 bacteria : 32 Baja California: 153 Baker Canyon member: 7 4 Baker, C. L. : 97 Balanophyllia: 31, 33 Baluchicardia: 107 ( Baluchicardia) ameliae popenguinensis, Veneri­cardia: 107 heaumonti, Venericardia: 106 hulla, Venericardia: 107 Venericardia: 9 Barbados: 177 harhata, A. : 57 Barhatia: 57 Barhatia : 59 Gray: 57-59 uxorispalmeri: 8 Barhatia ( Barhatia) harhata: 57 uxorispahrieri: 41, 42, 58-59,.100, 198 Barbatia ( Cucullaearca) cuculloides: 58 ludoviciana: 42, 58, 59 ( Barbatia) cuculloides ludoviciana, Arca: 58 haronneti, Venericardia: 102 harrier islands: 35 Barry, J.O'K.: 68, 100 Barry & LeBlanc: 68, 100 Bartonian: 91, 102, 160 Bashi marl member: 46, 47, 48, 50, 90, 100, 174 Bassano: 170 Bastrop: 51, 52, 136, 137, 151 Connty: 45, 48, 49, 51, 52, 55, 67, 69, 85, 88, 90, 114, 136, 137, 145, 147' 149, 155, 157, 166, 167, 168, 173, 176, 181, 197, 199, 201, 209, 210, 213, 214 J. D. Creek: 197 -Fayette County line: 150, 210 River: 136 -Smithville road: 199, 201, 209 hastropensis, Calorhadia (Litorhadia?) : 8, 51­52, 53, 197 Leda: 51, 52 Lima ( Ctenoides) : 8, 41, 90-91 Meretrix trigoniata: 136, 137, 160 Batesville-Dilley road: 157 Bathonian : 7 4 Bay of Panama: 153 Bear Branch School: 162 heaumonti, Cardita, group: 106 Venericardia ( Baluchicardia) : 106 Beaver Creek: 147 Becerra Creek quadrangle: 157 Belgique: 84 bellarugosa, lnoperna : 7 4 Belosepia: 31 Benchley: 19 bentonite: 19 Berlin, Academy of Sciences in: 11 Berryman's place: 146, 147, 211 Bienville Parish, Louisiana: 48, 100, 114 Big Bend National Park: 75 Black Creek formation: 7 4 Black Sea: 123 Black Shoals on Brazos River: 106 Blagraveia : 126 Blakeley formation: 133 Blanc, R. J. le: 68, 100 Blanding, Dr. : 127, 128, 129 blandingi, Venericardia: 129 Bocas del Toro Island, Panama: 53 bocasensis, Orthoyoldia: 53 Boehm, G. : 89 Boggy Creek : 77, 200 Bolten, J. F.: 87 Bononian : 7 4 Born, Ignatius: 78, 89, 120 Borson, S.: 71 boulders: 22 Boule, Marcellin: 74 Bowden formation: 53 Bowles, Edgar: 101, 103, 104, 106, 107 Brachidontes: 73 Brackelsham Beds: 83 ( Brazaturia) brazoensis, Aturia: 99, 100, 201 brazoensis, Aturia (Brazaturia): 99, 100, 201 Brazos County: 10, 14, 16, 20, 55, 61, 79, 85, 114, 137, 145. 148, 149,162 Mosley's Ferry in: 146, 178 -Robertson County line: 115, 207 Brazos Junction: 16 Brazos River: 10, 11, 16, 43, 47, 51, 54, 67, 76, 98, 114, 121, 127, 132, 143, 146, 160, 162, 163, 166,171,172,174,176,178 Black Shoals on: 106 ferry: 11 Brazil: 86, 177 Rio de Janeiro: 53 Brewster County: 75 British Isles: 59 British Museum of Natural History: 57, 115 Brockenhurst, England: 91 Brocchi, G.: 71, 115, 160 Broderip, : 153 Bronn, H. G.: 108, 110, 115, 116 Brown, : 169 Bruguiere, J. G.: 86, 87, 90 plate headings of: 86 Bryan: IO, 17 -Caldwell road: 10 -Hearne road: 61 bryozoa: 7, 31, 34 Buch, Leopold von: 11 Bucquoy, Dautzenberg &Dollfus: 87, 169, 170 Bucquoy,Eugene:87, 169,170 bul1a, Venericardia ( Baluchicardia) : 107 Burke County, Georgia: 97 Burleson County: 7, 10, 11, 16, 19, 51, 106, 145, 181 Collier's Ferry in: 146 Burman, B. H. : 184, 185 Burns: 54 burrow: 7 filling: 30 Bush, K. J.: 53 Byram marl: 80, 174 Bys.soarca missis.sippiensis: 58 bys.sal plugs : 9 byssus: 27 plug: 99, 201 thread: 27 Caddo Parish, Louisiana: 55 Caddo Peak: 39, 40 Caddo Post Office: 39 Cadulus: 31 cainei, Pachecoa: 42, 62, 63, 199 Trinacria ( Pachecoa) : 62 Calappidae: 29 Calappilia: 7 diglypta: 29 Calcaire gros.sier: 84, 101, 102, 106, 111 calcite: 25 Caldwell: 10, 11, 16 County: 11, 48, 121, 123, 172 California: 74, 101, 108, 133, 148, 153, 170 Company: 112 Cretaceous, Gabb's: 49 Fresno Ceunty: 107 Lower: 48 californianus, Pitar: 148 californica, M.: 145 Callista sulcataria, Desh.: 141 Callocallista arnoldi: 133 Callocardia­( Agriopoma) amichel: 137 tornadonis: 148 astartoides: 151, 155, 156 fragment: 100 Calorhadia: 9, 47 compsa: 48, 49 costellata : 48 hammetti: 48 marella: 48 mater: 48, 49 opulenta: 48, 49 pharcida: 48, 49 potomacensis: 48 praecompsa: 48, 49 reginajacksonis : 48, 49 S.S.: 47, 48, 49 Stewart : 46-53 Calorhadia (Calorhadia) compsa: 8, 47-49, 197 costellata: 47 marella: 47 pharcida : 46 praecompsa: 8, 41, 49, 197 Calorhadia (Litorhadia): 49 albirupina: 52 aldrichiana: 50 bastropensis: 8, 51-52, 53, 197 compsa: 47 evanescentior: 8, 41, 52-53, 197 petropolitana: 8, 41, 50-51, 197 Cal pitaria: 142, 150 citrinus, Pitar: 142 Jukes-Browne: 141-151 parisiensis, Pitar: 141, 210 petropolitanus, Pitar: 9, 41, 143-145 147 148 150, 210 ' ' ' Pitar: 142 sulcatarius, Pitar: 141 texacola, Pitar: 9, 144, 145-147, 148 150 211 215 ' ' ' texibrazus, Pitar: 41, 143, 147-148, 211 tornadonis, Pitar: 9, 144, 145, 148-151, 210 transversus incurvatus, Pitar: 143 calvatus, Pecten : 85, 86, 129 Camden-Oakhill road: 177 Cameroons: 140 Camino Real: 11 Campania Gallorum.: 101 Campanian: 74 Campbellton: 39 Campiche, : 75 Camptonectes: 83, 85 claihornensis: 84, 85 scintillatus, Chlamys: 84 Canada: 95 canaliculata, Lutraria •.. of Say: 131 Canary Islands: 116, 170 candida, Pholadomya: 161 Cane River formation: 176 cannon-hall concretions: 24 Cape Hatteras, North Carolina: 89 Cape Verde Islands: 59, 116 cardiif ormis, Verticordia: 177 Cardita alticosta: 108 alticostata: 104, 107, 108, 109, 110 arivechensis: 108 beaumonti group: 106 densata: 103, 104,204 Mooreana: 104 planicosta: 129 suhquadrata: 114 transversa: 108, 110 (Venericardia) transversa: 108, 110 Carditicae: 41, 101-115 Carditidae: 9, 101-115 Carey, Lea &Blanchard: 107, 110, 130, 165 Caribbean Sea: 89, 120, 166 carinata, Psuedoliva: 204 carli, Corhula ( Caryocorhula) : 166 carolina, Trinacria decisa: 70 carolinensis, Inopema.: 7 4 Carrizo, Zapata County: 136 Caryocorbula Gardner: 165-168 alahamiensis: 165, 168, 212, 213 deusseni: 9, 166-168,213 ( Caryocorhula) carli, Corhula: 166 conradi, Corhula: 166, 167, 168 engonata, Corhula: 167 santanensis, Corbula: 166 sp., Corbula: 166 Caryocorbulinae: 165-176 Casey, I osephine: 42 Casey, T. L.: 15, 174 Cassel: 118, 140 Castle Hayne marl: 84 Catahoula Parish, Louisiana: 80 catonis, Pachecoa: 8, 41, 65, 68-71, 199 Caton's Bluff: 68, 199 cawcawensis, Atrina: 8, 27, 29, 78, 200 Caw Caw Swamp: 63 C. citrina, Lam.: 142 C. Conradi: 168 C. cubitus ( Desh.) : 91 Cedar Creek : 11, 114, 115, 146 Town Branch of: 207 Cenomanian : 95 Cretaceous: 40 Center Union Church and School: 90, 114, 201 Centerville-Concord road: 165, 211, 212 Cerithium: 100 Cerralvo, Nuevo Le6n, Mexico: 100 Chantegrain of Maintenon: 202, 210 Charles County, Maryland: 48, 100 Chaum.ont-en-Vexin, France: 84, 142 Chavan, Andre: 116 Chemnitz, : 87 Cherokee County: 146, 147, 162, 163 cherokense, Ectinochilus texanum: 203, 211 chevron ridge: 152 Chickasawan: 113 Chickasawhay River: 178 China Sea: 177 Chipola formation: 106 Chiriqui, Panama: 48 Chlamys ( Camptonectes) scintillatus: 84 Cihota mississippiensis: 58 citrina, Cytherea : 142 citrin us, Pitar (Cal pitaria) : 142 claiboplata, Venericardia (Venericor) : 104 Claiborne-­group: 7, 14, 18, 44, 45, 46, 48, 49, 50, 52, 53, 55, 59, 60, 61, 82, 83, 91, 97, 109, 128, 130, 133, 134, 137, 145, 146, 147, 151, 153, 155, 157,158, 162,163,178,179,180 sand:43,54, 78,179 stage: 14, 47, 51, 54, 61, 65, 66, 67, 72, 73, 75, 78, 84, 92, 95, 108, 110, 111, 114, 121, 127, 130,143,145,148, 162, 166, 171,174, 176 Claiborne Bluff, Monroe County, Alabama: 45, 46, 48, 54, 58, 60, 64, 69, 70, 71, 82, 93, . 97' 100, 103, 104, 105, 106, 109, 111, 113, 117, 119, 122, 126, 127, 128, 132, 138, 153, 155, 157, 15~, 164, 165, 179, 198, 199, 200, 206, 207,209,211,212,213 Claiborne, Monroe County, Alabama: 10, 14, 43, 54, 55, 73, 103, 108, 112, 127' 128, 131, 132, 146, 179,202,204,208 claibornense, Pseudamussium: 85 claibornensis: 85 Camptonectes: 84, 85 harrisi, Pholadomya: 162, 163 Nucula: 55 Orthoyoldia: 53 Pecten: 84, 85 Pholadomya: 164 CJaibornicardia: 9, 41, 105, 106, 115 Stenzel & Krause: 104-115 ( Claibornicardia) , Venericardia : 9 acuticosta: 106, 107, 111 alticostata: 8, 9, 104, 105, 107-109, 111, 112, 206, 207 complexicosta: 8, 106, 107, 111-114, 208 sillimani : 8, I 06, 107, 110--111, 112, 206, 207 trapaquara:8,34,106,107, 113,114-115,207 Clark, W. B.: 46, 48, 84, 100, 117 Clark &Martin : 46, 48, 100, 117 Clark, Miller & Others: 84 Clarke County, Alabama: 39, 46, 48, 50, 100, 174, 200 Mississippi: 46, 60, 79, 82, 113, 178, 179, 198, 200 clay-ironstone: 19, 23, 29, 30, 150 Cleburne: 39 · Clementiinae: 135 Clyde Sea: 30 C. nuttaliopsis Heilp.: 145 coefficient of variability: 185 College Station: 14 Collier's Ferry, Burleson County: 106, 146 coloration: 136, 144 Color Chart: 20 Colorado River: 45, 49, 52, 67, 88, 136, 137, 150, 151, 157, 168, 173, 176~ 180, 197, 199, 201, 209,210,213,214 Columbia, South Carolina: 126 Road: 80 Columbia-Orangeburg highway: 63, 199 Bureau of Economic Geology, The University of Texas Columbus, Louisiana: 61, 66, 96, 198, 199 Comanche Crossing: 82 Committee on Pelecypoda of the Treatise on In­vertebrate Paleontology: 38 compaction: 162, 164 complexicosta, Venericardia ( Claibornicardia) : 8, 106, 107, 111-114,208 compound costae, tripartite: 105 compressa: 175 Corbula: 172 compsa, Calorhadia: 47-49 ( Calorhadia) : 8, 197 (Li tor hadia) : 4 7 Leda: 47 opulenta: 47 Nuculana: 47 ( Compsomyax) Katherinella: 135 Stewart: 135 concentricecostellata, lnoperna: 7 4 Concord-Centerville road: 165, 211, 212 concretions : 23 marcasi te : 24 phosphorite: 165 Conecuh County, Alabama: 39, 106 Conecuh River: 68, 199 Conehatta, Mississippi: 112, 208 conglobata Monterosato: 169, 170 conglomerate: 7, 19, 21, 22 Conrad, T. A.: 8, 9, 10, 15, 21, 39, 42, 43, 46, 47, 48, 53, 54, 55, 58, 60, 61, 64, 65·, 66, 68, 69, 70, 71, 72, 74, 75, 78, 80, 82, 83, 84, 85, 92, 93, 97, 98, 99, 100, 101, 103, 105, 106, 107, 108, 109, 110, 112, 114, 117, 118, 121, 122, 125, 126, 127' 128, 129, 130, 131, 132, 133, 148, 153, 154, 155·, 158, 164, 168, 171, 180, 198,200,201,203,204,206,207,208,209 Conradi, Astarte : 126 c.: 168 Lutraria: 126 Pteropsis: 126 conradi, Astarte: 127, 128 Corbula: 168 ( Caryocorbula) : 166, 167, 168 Pteropsis: 127 Cooke,C. VI.: 101, 127,130 Cooke &MacNeil: 101, 127, 130 Cook Mountain : 52, 91 formation: 7, 8, 9, 11, 14, 18, 19, 20, 22, 44, 45, 48, 50, 51, 54, 55, 59, 60, 61, 62, 69, 73, 76, 77' 78, 79, 83, 85, 86, 90, 92, 93, 95, 96, 97' 99, 100, 101, 104, 105, 106, 112, 113, 114, 117, 122, 123, 125, 128, 137, 145, 148, 150, 151, 153, 155, 156, 157' 162, 163, 164, 167, 168, 173, 176, 178, 179, 180, 182, 184, 197, 198, 200,201,202,204,205,208,210,211,212 . Cook Mountain-Y egua boundary: 97 Coon Creek, Tennessee: 74 Coon Creek tongue: 7 4 Cooper marl: 101 Copenhagen: 89.. 154 copiapite: 21, 22 Corallian beds : 7 4 corals: 7, 31, 197 corbiscula, Diplodonta: 117 Corbula: 165 (Aloidis) texana: 171 alabamiensis: 165, 166, 168 aldrichi: 174 smithvillensis: 173, 174 ( Caryocorbula) carli: 166 conradi: 166, 167, 168 engonata: 167 santanensis: 166 sp.: 166 compressa: 172 conradi: 168 (Cuneocorbula) alahamiensis: 168 deusseni: 166 gregorioi : 174 gibba·: 169, 170 gregorioi: 167 nasuta: 154, 168 nucleus: 170 smithvillensis: 174, 176 rugosa: 174 texana: 115, 169, 170, 171 (Varicorbula) smithvillensis: 174, 176 texana: 171 Corbulas: 28 Corbulidae: 9, 27, 28, 29, 165-176 corbuloides, Pectunculus: 70 Corio psis: 160 suborbicularis, Sinodia: 160 Cornell University: 162, 163 Paleontological Museum: 63 corneoides, Eburneopecten: 83, 85 corneus, Pecten: 83, 84 scintillatus: 84, 85 Corps of Engineers: 10, 157 Islitas quadrangle: 151 Corrigan, Polk County: 146 corvamnis, Pachecoa? : 70 Cossmann, Maurice: 15, 70, 71, 72, 73, 84, 92, 108, 110, 130, 131, 132, 160, 167, 174, 175, 179 Cossmann &Peyrot: 160 Cossmann &Pissarro : 84 cossmanni, Halonanus ( Triacriella) : 72 Limopsis: 71, 72 Nanohalus:8,9, 70, 71, 72-73, 199 Trinacria: 71, 72 Verticordia ( Trigonulina) : 179 Costa, E. M. da: 59 Costa, 0. G. : 170 costae, tripartite compound: 105 cos ta ta, Ostrea : 92 costellata, Calorhadia: 47, 48 Costelloleda: 9, 47 Cotulla-Laredo road: 97 Country Club road: 68, 199 Courtagnon: 101 Covington County, Alabama: 68, 199 Cow Creek, St. Francis County, Arkansas: 62 Cowlitz formation: 148 Cox, L. R. : 7 4, 83, 126 Cox & Arkell : 7 4 crab: 29 Craddock tract: 76 Crag ( Gedgravian) of England: 177 Crane Pond: 61, 66, 96, 198, 199 crassa, Trigonocoelia : 64 Trinacria: 64 Crassatella alta: 126, 128 Crassostrea : 97 alabamiensis : 97 amichel: 97 frionis: 8, 34, 95, 99, 100, 205 gigantissima: 97 rhomboidea: 129 Sacco: 95-97 virginica: 95 Crenella: 75 Creole Bluff, Grant Parish, Louisiana: 79 Crepy en Valois, Departement Oise, France: 202 Cretaceous:40,43,46,47,56,58,59, 74,83,87,89, 102, 107, 108, 110, 116, 120, 121, 126, 130, 141, 159, 170 Gahb's California: 49 Crockett formation: 14, 18, 19 Crockett, Houston County: 76, 150, 162, 200, 210, 211, 212 Crockett quadrangle: 150 Crockett-Rusk county road: 76, 150, 200, ~10 Crow Creek: 70 crytogenic species: 172 Ctenoides: 89, 90 Ctenoides: 88, 90 Morch: 89 ( Ctenoides) hastropensis, Lima: 8, 41, 90-91, 201 ctenoides, Lima: 89 divaricata, Lima: 89 harrisiana, Lima : 90, 91 interstriata, Lima: 89 lingula, Lima: 89 rohinaldina, Lima: 89 scahra, Lima: 89 Radula: 89 tecta, Lima : 89 ctenoides, Lima ( Ctenoides) : 89 ctenolium: 84 C. tumens Gmel.: 140 Cuba: 177 Cubitostrea: 92 ameghinoi: 92 cubitus: 91, 92, 202 divaricata : 92-93 lishonensis: 94 perplica ta : 68 petropolitana: 100 prona: 91 rocana: 92 Sacco: 91-95 sellaef ormis: 130 smithvillensis: 89, 197 S.S.: 9] Cuhitostrea ( Cuhitostrea) divaricata: 8, 95, 202 cuhitus: 202 perplicata: 95 petropolitana: 8, 41, 94-95, 204 sanctiaugustini: 8, 41, 9&-94, 95, 203 cubitus, Cuhitostrea: 91, 92, 202 Ostrea: 91 Cucullaearca: 57, 58, 59 cuculloides, Barbatia: 58 ludoviciana, Barbatia: 42, 58, 59 cuculloides, Barhatia ( Cucullaearca) : 58 ludoviciana, Arca (Barbatia): 58 cuneata, Pholadomya: 165 ( Cuneocorhula) alahamiensis, Corhula: 168 deusseni, Corbula: 166 gregorioi, Corbula : 174 cuneus, Trinacria: 70 current action: 34-35 Cuvier, Georges: 86 C. virginiana ( Gmel.) : 95 Cymbulostrea: 92 Cyrenina: 133-161 Cythera texacola var. tornadonis: 144, 210 Cytherea: 140 discoidalis: 153, 154, 155 subcra~a: 153, 154, 155 sulcataria: 141 texacola: 147, 151, 211 trigoniata: 154, 155 vulnerata, Brod. : 153 da Costa, E. M.: 28, 29, 59 Dale County, Alabama: 90 Dall, W. H.: 8, 9, 15, 39, 46, 48, 49, 50, 53, 54, 55, 68, 70, 71, 72, 73, 74, 75, 78, 79, 83, 84, 89, 92, 95, 106, 107, 108, 110, 111, 112, 113, 116, 118, 120, 121, 122, 127, 130, 135, 153, 165, 167,168,171, 174, 179, 197, 199 dalliana, Verticordia (Trigonulina) : 178 Dana, J. D.: 126, 127, 128 Daradiceras gignouxi: 107 D'Archiac, : 106 D'Archiac & Haime: 106 Dautzenberg,Phillipe: 87, 169, 170 Davies, A. M.: 141 Day, J. R.: 97 De Blainv., : 104 Decatur, Mississippi: 112, 208 Newton road : 112, 208 decisa abbreviata, Trinacria: 69 carolina, Trinacria: 70 Pachecoa : 68, 69 Trinacria: 65 decisus, Limopsis: 65 Pectunculus: 65 declivis, Pachecoa: 68, 69, 70 Trinacria : 66 degree of inflation: 40 De Gregorio, Antoine: 92, 108, 110, 130, 131 Del-Guercio, : 64 Dellet glauconitic sand: 58, 179 De Loriol, P.: 74, 75 deltoides, Mysia: 117 Denmark, Ise Fiord, Sjaelland: 170 densata, Cardi ta: 103, 104, 204 Venericardia: 55, 104, 208 Venericardia (Venericor) : 103 planicosta: 8, 9, 99, 100, 103-104, 201, 204 densities, population: 29 Dentalium: 31, 203 dentata, Mactra: 130, 132 deposit feeder: 28 Deshayes, G. P.: 64, 83, 84, 89, 91, 92, 141, 142, 165,202,210 Desmodontida: 161-165 De Soto, Mississippi: 178 Deussen, Alexander: 14, 43, 47, 58, 65, 67, 84, 98, 121, 132, 166, 171, 174, 176 deusseni, Caryocorbula: 9, 166-168, 213 Corbula ( Cuneocorbula) : 166 Pteria: 82 devices, interlocking: 40 De Viller's ranch: 96 Devil's Eye: 136, 137, 151 dfo:lypta, Calappilia: 29 Dilley-Batesville road: 157 Dillwyn, : 78 Diplodon: 116 Diplodonta: 116, 117 Bronn: 115-118 (Felaniella) nana: 118 lupina: 115 rotundata: 115 Diplodonta (Diplodonta) corbiscula: 117 hopkinsiensis: 117 inflata: 117 marlboroensis: 117 petropolitana: 8, 34, 41, 116, 117-118, 201 satex: 117 Diplodonta ( Diplodonta )­ungulina : 118 yazoocola : 118 Diplodontidae: 115-118 discoidalis, Cytherea: 153, 154, 155 Omnivenus: 155 Rhabdopitaria: 155, 158 disconformity: 10, 18, 19 divaricata, Cubitostrea: 8, 92-93, 95, 202 Lima ( Ctenoides) : 89 Mut.: 92 Ostrea: 92 ( Cubitostrea) : 92 sellaef ormis : 92 Divesian: 75 Dobson, Judah: 130 Dodge, Henry: 43, 56, 57, S.9, 80, 86, 97, 120, 123 Dollf us, Gustave: 87, 169, 170 Dolores Creek : 97 Dominican Republic: 53 donacina, Tellina (Moerella) : 123 D'Orbigny, Alcide: 7 4, 75, 89, 108, 110, 177 Dosinia ( Sinodia) trigona: 159 D. trigonia (Reeve) : 159 Dujardin, : 89 Dumble, E. T.: 14, 42, 151 Dumble Survey: 42 duponti, Venericardia (Venericor) : 102 Dysodontida: 73-78 earbones, fish: 34 Eaton, Robertson County: 19, 20 lentil: 19, 20 Eburneopecten : 84 Conrad: 82-86 corneoides: 83, 85 scintillatus: 8, 82, 83, 84--86, 200, 203 Pecten: 84 solea: 83 echinoids: 31 Ectinochilus texanum cherokense: 203 texanus plan us: 203 Edwards, : 143 effiorescences, jarosite: 24 El Camino Real: 12 Elkhart, Anderson County: 117 ellipsis, Pachecoa (Stenzelia) : 70 Pectunculus: 64 Elm Creek, Lee County: 44, 197 elongatoides var.?, Leda?: 50 E. L. R. Wheelock survey: 115, 207 Emery, K. 0.: 32 Emery & Rittenberg: 32 Emory, W. H.: 168 Encyclopedie Methodique: 89, 90 endings, new, of superfamilies: 41 uniform: 38 Endopachys: 31, 33 En~land: 33, 74, 75, 83, 116, 160 Brockenhurst: 91 Gault of Folkstone: 46 Lyndhurst: 91 Minchinham pton: 7 4 Suffolk : 177 English coast : 80 Enterprise, Mississippi: 82, 84, 93 eocaenica, Sinodia: 9, 41, 159, 160-161, 206 eocensis, Verticordia: 179 ephippioides, Anomia: 8, 9, 97, 98-101, 115, 201, 202, 204 Espejo farm and ranch: 157 Etallon, A.: 74, 75 etheringtoni, Katherinella arnoldi: 138 Eulamellibranchia: 101-176 Europe: 59,64, 74,91,97, 102,160,170 European seas: 43, 123 Eutaw Springs: 85, 130 -Santee-Vance road: 129 Eutawville, Orangeburg County, South Carolina: 86 quadrangle: 129 Eurytellina Fischer: 120-123 mooreana, Tellina: 8, 121-123, 208 pa pyria, Tellina: 208 punicea, Tellina: 120 evanescentior, Calorhadia (Litorhadia?): 8, 41, 52-53, 197 Evergreen, Virginia: 117 evolutionary lineages: 107 exhaJant: 27 siphon: 28, 30 Exogyra ponderosa: 7 4 ~xudates: 22 faecal pellets: 30, 31 faeces: 7 f alcif ormis, Ostrea: 93 family: 38 Faria pump: 151 Farias Siding: 151 Farm Road 39: 165 228: 147' 215 1870: 90, 114, 201 Fayette County, Shipp's Ford in: 149 -Bastrop County line: 150, 210 feeder, deposit: 28 suspension : 27 Felaniella: 118 nana, Diplodonta: 118 ferry: 10, 11 Fiji Islands: 87 Filibranchia: SS-73 filling, burrow: 30 Finch, John : 97 Fischer, Paul H.: 120, 123, 130 Fischer-Piette, E. : 140 fish ear bones: 34 Flabellum: 31, 33 flagellifera, lnoperna: 74, 75 Florida: 46, 54, 72, 75, 84, 86, 89, 92, 106, 108, 110, 111, 121,127, 130, 165, 171,174 Flynn-Jewett road: 165 Folkestone, England: 46 Forbes, Edward: 74, 75 Forrest City, St. Francis County, Arkansas: 62, 70 Fort Washington, Maryland: 164 Fort Worth: 39 fragilis, Atrina: 26 Lima ( Limatulella) : 87 of Mont.: 87 Ostrea: 87 Pecten: 87 France: 92, 106, 160 Chaumont-en-Vexin: 142 Crepy en Valois: 202 Houdan: 141, 210 Kimmeridgian of: 7 4 Paris: 73, 142 Basin: 102 Parnes: 142 Seine et Oise: 101, 141, 142 Senlis: 91 Valmondois: 91 Fredericksburg group: 74, 75 French edition : 177 French West Africa, Guinea: 215 Fresno County, California: 107 Frio County: 39, 96 frionis, Crassostrea: 8, 34, 99, 100, 205 Ostrea: 95, 96 alahamiensis: 95 Ft. Gaines, Ga. : 52 Furon, Raymond: 91 Furon &Soyer: 91 fusca, B., D., &D.: 169 Gahh, W. M.: 8, 9, 10, 11, 14, 15, 39, 40, 42, 47, 49, 53, 58, 62, 63, 64, 65, 66, 67' 69, 98, 99, 100, 101, 108, 111, 121, 122, 123, 159, 169, 170, 171, 172, 197, 199,201,202,204,208,214 gahhii, Turricula (Protosurcula) : 21 Gabh's California Cretaceous: 49 Gale, H. R.: 9, 169, 170 Galenus: 60 Galeotti, : 71 Galvin Station, Lewis County, Washington: 133 Gardner, Julia: 9, 15, 43, 44, 47, 49, 51, 52~ 54, 64, 65, 82, 84, 95, 97, 98, 100, 101, 103, J04, 106, 107, 117,118,121,122, 127,136,137,139, 145, 148, 151, 152, 153, 154, 155, 156, 158, 162, 163, 164, 165, 166, 167, 168, 171, 172, 174, 176,178, 179,211,213 Gardner &Bowles: 101, 103, 104, 106, 107 Garland's Creek; Clarke County, Mississippi: 46, 79, 82, 85, 200 Garrett, Kennedy: 144 Gault of Folkestone, England: 46 Gazley Creek: 69, 157, 199 Gedgravian (Crag) of England: 177 Geinitz, : 89 gender:38,60,141,161 genera, new: 41 General Landoflice, Austin: 10 Generic Names in Zoology, Official List of: 55 Geological Sketch of Texas: 14 Geological Survey of Texas: 42 Georgia, Burke County: 97 Ft. Gaines: 52 georgiana, Ostrea : 97 Germany, Lattorf: 91 gihba, Corbula: 169, 170 group: 169 N otocorbula: 27, 28, 33 Tellina : 170 Varicorhula: 170 Giddings: 44, 197 -Manheim road: 44, 197 gigantis'1ima, Cr~ostrea: 97 gignouxi, Daradiceras: 107 gillieroni, lnopema: 75 glauconite: 21, 22 arenite: 21 main: 23, 30 marl: 21 glauconitic marl: 21 Glycymeridicae: 41, 59-73 Glycymerididae: 59-61 Glycymeris: 59, 60 da Costa: 59-61 glycymeris: 59 lisbonensis: 60, 61 orbioularis: 59 petropolitana: 8, 41, 60-61, 198 sabinensis: 60, 61, 66, 198 staminea: 61 trigonella: 60, 61, 198 wautubbeana: 60, 61, 198 glycymeris, Arca : 59 Glycymeris: 59 Glyptoactis: 106 Gmelin, J. F.: 87, 95, 101, 140, 215 Goddard, E. N. : 20 goethi te : 21 Goldfuss, August: 89, 93, 160 Gonzales County: 172 Gorgonacea : 197 Gosport formation: 106, 125, 153 sand: 8, 46, 48, 54, 55, 60, 64, 70, 71, 82, 93, 97, 105, 106, 109, 111, 113, 117, 119, 126, 128, 132, 138, 153, 15.S, 157' 159, 165, 168, 179, 198, 199,200,206, 207,20~ 211, 212,213 Gotha: 120 grain-size identification: 21 Grand Gulf. of Mississippi: 113 Grant Parish, Louisiana: 79 Grant, U.S., IV: 9, 169, 170 Grant & Gale: 9, 169, 170 Grapeland-Percilla road: 147, 215 Grave, B. H.: 27 gravida, Pinna : 79 Gray, D. M.: 73 Gray, J.E.: 57, 78,87,116,161 Great Britain : 177 Great Oolite: 74 Greek: 60, 125 petrosa : 127 greensand marl bed: 80 Greensand, Upper: 74 Green's marl bed: 79, 80 Gregorio, Antoine de: 92, 108, 110, 130, 131 gregorioi: 175 Corbula: 167 ( Cuneocorbula) : 174 Grignon, France: 101, 102 Groos, Karl: 115 Guinea, French West Africa: 215 Gulf of Califomia: 153 Gulf of Mexico: 53, 56 Gurabo formation: 53 gypsum: 22, 23 hadra, Venericardia: 106 Haime, : 106 Haliris: 179 mississippiensis, Verticordia: 179 quadrangularis, Verticordia : 179 Hall Summit formation : 100 Halonanus: 9, 62, 63, 64 pulcher: 62,63,64,66 pulchrus: 65 ( Stenzelia) : 72 ( Triacriella) cossmanni: 72 ( Trinacriella) perplana: 64 hammetti, Anomia: 100 Calorhadia: 48 Hammett's Branch, Bienville Parish, Louisiana: 48, 100 Hanna, : 47, 48 Harbison, Anne: 42, 84 Harper's Bend: 96 Harnett County, North Carolina: 80 harnetti, Pinna: 80 Harris, G. D.: 8, 9, 14, 15, 21, 27, 29, 34, 39, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, S6, 58, 59, 60, 61, 62, 63,64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 89, 90, 91, 92, 94, 95, 96, 98, 99, 100, 103, 106, 107, 108, 110, 111, 112, 113, 114, 115, 117, 118, 121, 127, 128, 130, 132, 136, 137, 143, 144, 145, 146, 14~, 148, 149, 150, 154, 155, 162, 163, 165, 166, 171, 172, 173, 174, 175, 176, 177, 178, 180, 182, 183, 184, 197, 198, 199, 200, 203, 205, 207 210, 211, 214, 215 ' Harris & Palmer: 44, 46, 48, 49, 58, 62, 64, 70, 81,82, 115, 118, 178 Harris reprint : 125 harrisiana, Lima ( Ctenoides) : 90 91 harrisi, Pholadomya: 9, 162-163', 164, 165 211 212 ' ' claibornensis: 162, 163 Pteropsis: 127, 128 Harvard University: 154 Hatchetigbee Bluff, Washington County, Ala­bama: 56, 85, 107, 117 Hatchetigbee formation: 46, 47, 48, 50, 56, 83, 90, 100, 107, 117, 174 hatchetigbeensis, Arca: 56 Headon beds: 91, 142 Hearne-Bryan road: 61 Hebrides: 123 height of a shell : 40 Heilprin, Angelo: 39, 47, 84, 85, 104 108 121 ' ' ' 126, 128, 145, 171, 174 hematite: 21 Hertlein, L. G.: 9, 47, 48, 120, 153 Hertlein, Hanna & Strong: 47, 48 Hertlein & Strong: 9, 47, 48, 120, 153 Herrmannsen, A. N.: 115, 118 hesperia, Venericardia: 106 Heterodontida: 101-161 hexacorals: 7, 31, 33, 197 hiatus: 10 Highland, or Sprunt, Farm: 80 Hinds County, Mississippi: 46, 48, 79 82 179 hinge axis : 40 ' ' hirundo, Mytilus: 80 Pteria: 80 Hiwanee railroad station, Wayne County Missis­sippi: 178 ' Hodge survey: 76 holothurians: 29 homonym: 115 hopkinsiensis, Diplodonta: 117 Houdan,France: 141,210 Houston: 41 County: 51, 73, 76, 79, 115, 127, 137, 140, 145, 147, 152, 153, 155, 156, 158, 162 200 210 211, 212, 215 ' , ' Alabama Ferry: 115, 137, 138, 140, 152, 153, 155, 156, 157, 158, 162,209,211,215 Crockett: 150 Hurricane Bayou: 146, 149, 151, 181 Percilla: 147 rock flat near: 146 East &West Texas R.R.: 146 houstonia, Leda: 51 Lithophaga: 75 Mauricia: 8, 73, 74, 75-77, 200 Modiola: 73, 7 4 houstonius, Modiolus: 75 (Mauricia) : 73 Howe, H. V.: 97 Hurricane Bayou, Houston County: 73, 76, 127, 136, 137, 146, 149, 150, 151, 162, 181 200 210 , , Hurricane lentil: 51, 73, 77, 79, 137, 145 151 181 182, 183,200,210 ' ' , hydrotroilite: 32 Iceland: 97 Ihering, H. von : 92 imbricata, Venericardia: 101 Venus: 101 imprints, track-like: 197 lncertae sedis : 127 incrassata, Venus: 160 India: 74, 75, 126 Indian trail: 11 lndo-Pacific Ocean: 87 inequivalvis, Mya: 170 inflata, Diplodonta: 117 Ostrea: 87 Radula: 87 inflated, definition of: 40 inflation, degree of: 40 inflation of a valve: 40 inhalant siphon: 27, 28, 30 Inoceramus: 75 Inoperna: 9, 74, 75 baini: 75 bellatugosa : 7 4 carolinensis : 7 4 concentricecostellata: 74 ebrayi: 75 flagellifera: 7 4, 75 gillieroni: 75 icauensis: 75 lignea: 74 medu.s: 74, 75 perplicata: 74, 75 plicata: 74, 75 siliqua: 75 interlocking devices: 40 International Commission on Zoological Nomen­clature: 86, 116 ~nterna~ional ~oological Congress: 154 interstnata, Lima ( Ctenoides) : 89 lz:edale, Tom: 9, 78, 168, 170 iron minerals: 21 lse Fiord, Sjaelland, Denmark: 170 lslitas quadrangle: 151 Isodontida: 78-101 lsraelsky, M. C.: 107 Italy, Piedmont of: 116 Ithaca, New York: 42, 59, 62, 66, 80, 162, 163 Jackson group: 8, 46, 47, 48, 52, 53, 58, 62, 70, 82, 83, 84, 85, 86, 97, 103, 114, 118, 130, 179 Jackson, Clarke County, Alabama: 200 Jackson, Hinds Couniy, Mississippi: 46 48 79 82, 85, 179 , , ' Jackson Parish, Louisiana: 155, 180 Jackson, R. T.: 98 Jackson specimen: 78 Jacksonian: 79 j acksoniana Dall : 78 Atrina: 79 Jamaica: 53 Jamaique: 177 Japan: 86 Sea: 177 jarosite: 21, 22 effiorescences: 24 J. D. Creek, Bastrop County: 197 Jefferson County, Arkansas : 52 Jewett-Flynn road: 165 Johnson, C. W. : 15 Johnson County: 39 johnsoni, Lopha: 68 Jourdanton: 167 jugosa, Anomia: 101, 201 Jukes-Browne, A. J.: 141, 142, 153, 159, 160 juvenis De Gregorio, Mut.: 110 Mut.: 108 Jurassic: 57, 74, 75, 83, 89 Katherinella: 134, 135, 139 arnoldi: 133 etheringtoni : 138 Pitaria: 133 (Compsomyax): 135 smithvillensis: 9, 41, 135-137, 138, 209 Tegland: 133-140 texitrina: 9, 41, 138-140, 209, 215 trigoniata: 138, 155 trinitatis: 9, 41, 137-138, 139, 209 Keidelberg: 115 Kellog, Mr.: 11 Kellogg, Mr. : 15 Kellum, L.B.: 84 Kennedy, William: 11, 14, 115, 144, 147, 171, 210, 211 Key & Biddle: 108, 110, 126, 130 Kimble headright: 147, 211 Kimmeridge clays: 7 4 Kimmeridgian of France: 7 4 Kincaid formation: 82, 117 King George County, Virginia: 46 Klein, Ludvig: 81, 89, 90 Knob Bluffs: 151, 156 Koenen, Adolf von: 91 Krause,i E. K.: 8, 9, 21, 27, 29, 41, 42, 48, 49, EO, -5.2, 53, 56, 57' 58, 59, 77' 104, 105, 123, 124, 128, 132, 133, 135, 137' 138, 139, 143, 144, 145, 147' 148, 150, 155, 158, 159, 160, 180, 197, 198,200,206,208,209,210,211,215 Krause & Twining: 21 Kymatox: 7, 9, 27, 41 lapidosus: 8, 126-130, 132, 133,208 pa pyria : 125 papyrius: 8, 128, 130-132,209 praelapidosus: 8, 9, 27, 29, 41, 124, 128, 132­133, 208 Stenzel & Krause: 124-133, 180 Kymatoxinae: 9, 41, 124-133 Ladd formation: 7 4 La Grange-Smithville road: 150, 210 Lake Marion: 129 Lamarck, J. B.: 74, 78, 80, 104, 106, 107, Ill, 115, 142, 170, 174 Lamarck, J. B. P. A. de: 43, 101, 102, 106, 118, 119 Lamarck, M. : 90 ( Lamelliconcha) , Pitaria: 39~ 155 (Lam ell in ucula) monroensis, N ucula : 4-S Laminaria : 27 Lamy, Edouard: 86, 87, 168, 169 Landrum member: 51, 73, 77, 137, 145, 151, 200, 210 Langdon, D. W.: 179 Langermann, A. B.: 10 lapidosa, Latin: 127 Lutraria: 126, 129 Pteropsis: 126, 127, 129, 132 Iapidosus, Kymatox: 8, 126-130, 132, 133., 208 La Perla oyster shales: 97 lapsus calami: 147 laqueata, V okesula: 174 Laredo : 151, 156, 157 -Cotulla road : 97 formation: 163 Laternulicae: 41, 161-165 Latin lapidosa: 127 Lattorf, Germany: 91 Lattorfian: 142 Oligocene: 91 Laurel-Meridian road: 113, 179, 198 Leach, : 87, 118, 119 Lea, H. C. : 108, 110, 130 Lea, Isaac: 8, 46, 51, 64, 70, 92, 93, 95, 97, 106, 107, 108, 109, 110, 117, 118, 119, 130, 132, 138, 153, 154, 155,157, 160, 165, 166,168, 172 Lea, : 202,206,207,211,212,213 Le Blanc, R. J.: 68, 100 Leda acala: 50 bastropensis: 51, 52 compsa: 47 elongatoides var.?: 50 houstonia : 51 opulenta compsa: 47 pharcida: 46 Ledidae: 53 ledoides: 66 Pachecoa: 70 Lee County: 44, 197 Leipzig : 115 length: 40 lens, Pecten: 83 Leon County: 19, 78, 128, 133, 145, 162, 165, 200, 211, 212 Leona River: 157 Jeonensis, Pholadomya: 9, 41, 163, 164-165, 211, 212 leonia, Mauricia: 8, 41, 200 le Pitar: 141 Lewis County, Washington: 133 Lewis' house: 163 Liassic: 98, 161 Liberty Hill-Quitman road: 155, 180 Libyan desert: 102 Liege: 86 lignea, lnoperna: 74 lignite: 20 xyloid: 22, 23, 24, 25 Li qni tic stage : 50 Liguria: 87, 91, 95 Lima : 86, 87, 90 alba: 86 Bruguiere : 86 ( Ctenoides) bastropensis: 8, 41, 90-91, 201 ctenoides: 89 divaricata: 89 harrisiana: 90, 91 interstriata: 89 lingula: 89 robinaldina: 89 scabra: 89 tecta: 89 (Lima) lima : 86 ( Limatulella) fragilis: 87 ozarkana : 90 petropolitana: 8, 88, 201 smithvillensis: 8, 41, 88-89, 201 tuberculata: 87 Loscombii: 87 Ostrea: 87 lima, Lima: 86 Mantellum: 87 Ostrea: 86 Limatulella: 87, 88 fragilis, Lima: 87 ozarkana, Lima : 90 petropolitana, Lima: 8, 88, 201 Sacco: 86-89 smithvillensis, Lima: 8, 41, 88-89, 201 tuberculata, Lima: 87 limestone : 24 Limestone County: 82 Limicae: 41, 86-91 Limidae: 86-91 limits of variability: 185 limonite: 21, 24 Limopsis: 71, 72 aurita: 71 cossmanni: 71, 72 decisus: 65 perplana: 71, 72 perplanus: 72 limula, Pteria: 82, 200 vanwinkleae, Pteria : 82 Lincoln formation : 133 lingula, Lima ( Ctenoides) : 89 Linne, Carl: 43, 55, 56, 57, 59, 80, 86, 89, 95, 97, 101, 115, 120, 123, 140 Lisbon, Alabama: 43, 113, 164 Lisbon, Bluff, Monroe County, Alabama: 60, 69, 100 lisbonensis, Anomia: 99, 100, 101 Cubitostrea: 94 Glycymeris: 60, 61 Pachecoa (Subgenus?) : 69 Lisbon formation: 8, 54, 55, 60, 69, 91, 92, 93, 104, 113, 130,202,204,208 Lithophaga: 74, 75 houstonia : 7 5 lithotopes: 26 Little Brazos River: 17, 20, 55, 79, 85, 137, 148, 149, 162 Little Stave Creek: 200 Litorhadia: 49, 50, 51, 52 albiru pina : 51 Calorhadia: 52 aldrichiana, Calorhadia : 50 bastropensis, Calorhadia: 8, 51-52, 53 compsa, Calorhadia: 47 evanescentior, Calorhadia: 8, 41, 52-53, 197 mater Mr.: 51 petropolitana, Calorhadia: 8, 41, 50-51, 197 plicata: 51 Stewart : 49-53 Liveoak Church: 129 L. Loscombii (Sow.) : 87 locality no.­3-T-18: 159, 172, 211 7-T-l: 96, 205 11-T-2: 45, 49, 52, 55, 67, 88, 137, 168, 176, 197, 201,209,213,214 ll-T-29: 150, 210 ll-T-38: 69, 199 11-T-70: 114, 201 21.r..1: 55, 79, 162 26-T-l: 10, 181 26-T-6: 106 37..r ..6: 147 46a: 115 113-T-2: 73, 127, 150, 162, 181, 200, 210 113-T-7: 162, 211, 212 113-T-9: 51, 79, 162 113·T-36: 115, 138, 140, 153, 156, 158, 209, 211, 215 113-T-37: 147, 215 144-T-5: 44, 197 145-T-l: 165, 211, 212 145-T-38: 128, 133 145-T-69: 162 145-T-80 : 78, 200 197-T-3: 115, 207 201-T-l: 59 201-T-5: 96 201-T-15: 61, 199 201-T-20: 61, 198 201-T-25: 162 202-T-8 : 203 239-T-19: 157 La-7: 180 La-8: 80 La-15: 162, 180 Miss-51 : 112 locality 21 of Veatch: 61, 66, 199 22 of Veatch : 96, 98 23 of Veatch: 96 Lodo formation: 107 London: 116, 118 clay: 108 Lonsdale, J. T.: 97 Lonsdale & Day: 97 Lopha johnsoni: 68 Loscombii, L. (Sow.) : 87 Lima: 87 Louisiana: 20, 58, 113, 127, 155, 163, 166, 171, 175, 176 BienvHle Parish: 48, 100, 114 Caddo Parish: 55 Catahoula Parish: 80 Columbus: 61, 66, 96, 198, 199 Grant Parish : 79 Hammett's Branch: 48 Jackson Parish: 180 Mt. Lebanon: 113 Quitman : 180 Red Land: 39 Sabine Parish: 61, 66, 96, 100, 198, 199 St. Maurice: 162, 180 Winn Parish: 79, 91, 155, 162, 180 Lower California: 48 L. scabra : 89 Lucinicae: 41, 115-118 Lucinina: 101-133 Luckhardt, J. G.: 140 ludoviciana, Arca: 58 (Barbatia) cuculloides: 58 Barbatia ( Cucullaerca) : 42, 58, 59 Lufkin-Nacogdoches road: 159, 172, 211 lupina, Diplodonta: 115 lupinus, Diplodonta: 115 Venus: 115 Lutetian: 83, 84, 91, 106, 111, 141, 142, 160, 210 Lutraria canaliculata of Say: 131 Conradi : 126 la pidosa: 126, 129 papyria: 125, 126, 130, 131, 180 petrosa : 126, 127 Pteropsis papyria: 125 ·( Pteropsis) petrosa, Con.: 129 Lyth, A. L., Jr.: 112 Lyndhurst, England: 91 Maastrichtian: 7 4, 75, 107 MacNeil, F. Stearns: 42, 45, 62, 64, 72, 101, 127, 130 Mactra dentata: 130, 132 tenuis: 118 Mactricae: 41, 124-133 Mactridae : 9, 27, 124-133 Madden Creek: 155, 180 Madracis: 31, 33 Magdalena Bay: 153 magnifica: 43 mauricensis, Nucula: 43 Nucula: 46 yazooensis, N ucula : 46 Mail Route I: 76, 150, 200, 210 main glauconite: 22, 23 marl: 30 main taxa : 38 Malacca: 159 maldanid polychaete annelid worms: 7, 30 malinchae, Anomia: 100 Manheim-Giddings road: 44, 197 Mansfield, W. C.: 30 Mantell um: 87 lima: 87 Marble Quarry: 91 marcasite: 22, 23, 25 concretions: 24, 32 marella, Calorhadia : 47, 48 marl: 21, 30 slickensided: 23 marlboroensis, Diplodonta: 117 marlstone: 21 Marsh, Prof. : 128 Martin, G. C.: 46, 48, 100, 117 Maryland: 130 Charles County: 100 Fort Washington: 164 Pope's Creek, Charles County: 48 Prince Georges County: 117 marylandica, Anomia: 100 Pholadomya: 164 Masson, Victor: 108, 110 mater, Calorhadia?: 48, 49 Mr., Litorhadia: 51 Matheron, : 7 5 Matthews Landing marl member: 50, 177 Mauricia: 9, 73, 74, 75, 77 Harris: 73-78 houstonia: 8, 7 3, 7 4, 7 5-77, 200 houstonius, Modiolus: 73, 75 leonia: 8, 41, 77-78, 200 mauricensis: 43 N ucula: 8, 27, 43-44, 45, 197 Mauritania: 140 mauryi, Pholadomya: 165 maxima Bucquoy, Dautzenberg & Dollfus: 169 Mayer, C. : 64 M. californica Con.: 145 McBean formation: 8, 55, 62, 63, 70, 80, 130, 199, 208 mcgeei, Anomia: 100 McLeod's Mill, Mississippi: 178 mean of sample: 184 mediavia, Nucula: 45 Medicus, Xenocrates: 60 Mediterranean Sea: 43, 56, 59, 80, 86, 97, 116, 118, 123, 170 medus, Inoperna: 74, 75 Meek, F. B. : 83, 95 Mercenaria: 153 Meretrix texacola : 143, 145 tornadonis: 148, 149 trigoniata bastropensis: 136, 137, 160 yoakumii: 39 Meridian-Laurel road: 113, 179, 198 meridionalis, Nucula : 46 Mesozoic: 66 Mexia: 82 Mexican Boundary Report: 168 Mexico: 47, 51, 54, 65, 95, 98, 100, 103, 108, 121, 127, 130, 148,162, 166, 171,172, 174 Meyer, Otto: 8, 46, 48, 49, 66, 70, 106, 107, 111, 112,113, 173, 174,208 Meyer & Aldrich: 8, 46, 106, 107, 111, 112, 113, 208 microcancellata, Pachecoa: 68 Middleton-Sulphur Springs School: 77, 200 Midway group: 45, 50, 82, 100, 106, 107, 117, 160, 165, 166, 177 Milam County: 51 Miller, B. L. : 84 Minchinhampton, England: 7 4 Miocene: 53, 116, 138,160, 165, 166, 168 Mississippi: 8, 53, 84, 106, 108, 110, 112, 125, 126, 130 Clarke County: 46, 60, 82, 113, 178, 179, 198, 200 Decatur: 208 De Soto: 178 embayment: 54, 84, 103, 114 Enterprise: 82, 84, 93 Grand Gulf of: 113 Hinds County: 46, 48, 79, 82 Hiwanee railroad station: 178 Jackson : 48, 85, 179 McLeod's Mill : 178 Newton: Ill, 208 County: 112, 208 Red Bluff: 178 Sheebu ta : 200 Sims Siding, Yazoo City: 118 Vicksburg: 126, 174 Warren County: 80, 82, 119, 174 Wautubbee: 111, 179 Hills: 178 Wayne County: 178 Yazoo County: 118 missi ppiensis, Byssoarca : 58 Cibota: 58 V erticordia ( Haliris) : 179 Mitylus sowerbianus: 75 Modiola: 75 ho.ustonia: 73, 7 4 plicata: 75 texana: 39 Modiolus: 74, 75 houstonius: 75 (Mauricia) houstonius: 73, 75 ( Moerella) donacina, Tellina: 123 Fischer: 123-124 petropolitana, Tellina: 8, 41, 123-124, 215 Molinas pasture: 157 Monroe Conn ty, Alabama : 45, 46, 48, 55, 60, 64, 69, 70, 71, 82, 93, 97' 101, 104, 105, 106, 109, Ill, 117, 126, 132, 138, 153, 155, 157, 179, 198, 199, 200, 202, 204, 206, 207' 208, 209, 211, 212, 213 monroensis, Nucula ( Lamellinucula) : 45 Montagu, George: 33, 87, 115, 116, 118, 170 Monterey: 177 Monterosato, : 169 Montian: 102 Moodys Branch marl: 8, 46, 47, 48, 82, 83, 85, 86, 118, 179,200 Moody's Branch, Mississippi: 82 Moore, Francis: 11, 14, 15, 39, 103 Jr.: 40 Moore, H. B.: 30, 33 Moore, R. C.: 154 Moore, : 172 Mooreana: 104 Cardita: 104 Tellina: 121, 122 Venericardia: 103, 104, Ill Mooreana, Tellina: 115, 121, 122 (Eurytellina) : 8, 121-123, 208 pa pyria: 121 Venericardia: 104, 112, 113, 204 Morch, 0. A. L. : 89, 90 Morton, Dr.: 127, 128 Morton, S. G.: 85, 86, 108, 109, 110, 126, 129, 130 Moseley Ferry : 144 Moseley limestone: 23 Moseley's Ferry, Brazos River, Brazos County: 10, 146, 178 Mosely: 144 Mosely Ferry: 10, 210 Mount Lebanon, Bienville Parish, Louisiana: 114 Mount Tabor member: 78, 200 Mozambique: 87 Mt. Lebanon, La., 9467: 113 Mt. Selman formation: 163 mud cracks: 33 flats: 35 grains: 30 Mfiller, : 33 mulleri, Venericardia ( Pacificor) : 107 Munier-Chalmas, : 103 Murchison Creek: 147, 215 muscle imprint: 92 Mut. divaricata: 92 juvenis: 108, 110 rotunda: 108, 110 secans: 108, 110 silimani : 108 sillimani: 110 vermilla: 92 Mya: 161 inequivalvis: 170 Mya, myae, myacis: 161 Myae: 161 Myicae: 41, 165-176 Mysia deltoides: 117 Mytilicae: 41, 73-78 Mytilidae: 73-78 Mytilus hirundo: 80 sowerhyanus: 75 Nacogdoches: 11, 12 -Lufkin road: 159, 172,211 road, old: 11 nana, Diplodonta (Felaniella): 118 Nanjemoy formation: 46, 48, 100, 117 Nanohalus: 9, 41, 72 cossmanni:8,9, 70, 71, 72-73,199 Stenzel & Twining: 71-73 nasuta, Corbula: 154, 168 Venericardia: 106 naticoid snails: 199 National Research Council: 20 nautiloid: 100 Navasota Creek: 82 N egreet quadrangle: 97 New Braunfels: 11 New Caledonia: 78 Newcastle, Virginia: 128 Newell, N. D.: 83 new endings of superfamilies: 41 new genera, subfamily, subgenera: 41 New Jersey: 111 New South Wales: 168, 169 Newton, Mississippi: 111, 112, 113 County: 112, 208 -Decatur road: 112, 208 Newton, R. Bullen: 160 New York, Ithaca: 42, 59, 62, 66, 80, 162, 163 Nicol, David: 42 Nigeria : 160 nigra, Pinna : 78 9467 Mt. Lebanon, La.: 113 nitens, Abra: 119 nitida, Abra: 33 noae, Arca: 55 N oetia pulchra : 62, 65 Noetiidae: 9, 42, 61-73 nomen nudum: 100, 126 North Africa: 103 North America: 91, 95, 107, 130, 134, 160, 166, 177 Pacific Slope of: 66 North Carolina : 84 Cape Hatteras: 89 Harnett County: 80 Snow Hill: 74 North, F. K.: 83 North-Orangeburg road: 63, 199 Norway: 43, 118, 170 Notocorhula: 7,9, 169, 170, 172 gibba : 27, 28, 33 Iredale: 168-173 texana: 159, 170-173, 214 vicaria: 168, 170 nucleus, Corhula: 170 Nucula: 43 nucleus, Lin., Arca: 43 N ucula: 7, 29, 40, 45, 46 austinclarki: 45 claihornensis : 55 Lamarck: 43-46 ( Lamellinucula) monroensis: 45 magnifica mauricensis: 43 yazooensis : 46 mauricensis: 43 ( N ucula) magnifica: 46 mauricensis: 8, 27, 43-44, 45, 197 · media via: 45 meridionalis: 46 ovula: 46 potomacensis : 46 smithvillensis: 8, 41, 44-46, 197 spheniopsis: 46 nucleus: 43 ( Pectinucula) pectinata: 45 ripae: 45 . sensu stricto : 43-46 N uculacea : 38 N uculana compsa: 4 7 psammotaea, Y oldia: 54 Nuculanicae: 41, 43-55 N uculanidae: 46-55 Nuculicae: 9, 38, 41, 43-46 Nuculidae: 27, 29, 43-46, 53 Nuevo Leon, Mexico: 100 nuttaliopsis, C.: 145 N. vicaria Iredale : 168 nymphs, rugose: 153 Nyst, : 71 Nyst & Galeotti: 71 Oakhill, Wilcox County, Alabama: 177 -Can1den road: 177 -Selma road : 177 Oak Hill P.O., Wilcox County, Alabama: 177 Oculina: 31, 33 Official List of Generic Nam es in Zoology: 55 Oise, France: 101, 141, 142, 202 Oldhaven beds: 142 old Nacogdoches road : 11 Old Spanish Road: 11, 12, 61, 115, 207 Oligocene: 38, 47, 53, 80, 82, 84, 91, 101, 119, 130, 133, 134, 142, 160,171, 174,178 olimpica, Tellina: 170 Olivi, Giuseppe: 27, 28, 33, 87, 169, 170 Olson, Axel A. : 42 Olsson, : 53 Omnivenus: 9, 153, 154 discoidalis : 155 Oppenheim, Paul: 84 opulenta, Calorhadia: 48, 49 com psa, Leda : 4 7 stock: 49 orangeburgensis, Orthoyoldia psammotaea: 55 Orangeburg, South Carolina: 55, 62, 63, 70, 76, 80, 127, 128, 129, 199 -Columbia highway: 63, 199 County: 55,63,86,128,199,208 District : 43 -North road: 63, 199 o~bicularis, Glycymeris : 5·9 order: 38 Oregon: 148 Orell's Crossing, Elm Creek, Lee County: 44, 197 ornata, Trigonulina: 177 Verticordia Cfrigonulina) : 177 Orthoyoldia: 53, 54 hocasensis: 53 claibornensis : 53 ovalis: 53 psammotaea: 8, 53, 54-55, 197 orangeburgensis : 55 sensu lato: 55 vivianensis: 55 Yoldia: 54 rubamnis : 53 scapina: 53 sea pania : 53 serica: 53 solenoides: 53 Verrill &Bush : 53-55 Ostrea: 87 alabamiensis : 95, 115 frionis: 95 costata: 92 ( Cubitostrea) divaricata: 92 cubitus: 91 divarfoata: 92 falciformis: 93 fragilis : 87 frionis : 95, 96 georgiana: 97 inflata: 87 Hrna: 86 Lima: 87 prono: 91 scabra: 89 sellaeformis: 92, 94, 128, 129, 130 divaricata: 92 semilunata: 92 soleniscus: 95 S.S.: 92 virginica : 95 Ostreicae: 41, 91-97 Ostreidae: 91-97 Ostreinae: 91-97 ovula, N ucula : 46 overinflated, definition of: 40 ovalis, Orthoyoldia: 53 Pachecoa (Subgenus?): 69 ( Trinacria) : 63 oyster reefs : 34 Ozark, Dale County, Alabama: 90 ozarkana, Lima (Limatulella) : 90 Pachecoa:9,62,64,68, 70 cainei: 42, 62, 63 Trinacria: 62 corvamnis : 70 Harris: 61-71 (Pachecoa) adamsi: 68, 199 cainei: 199 catonis: 8,41,65,68~71, 199 decis a : 68, 69 declivis: 68, 69, 70 ledoides: 70 microcancellata: 68 pectuncularis: 70 pulchra: 8, 65-66, 69, 199 sabinica: 8, 61, 66, 69, 199 smithvillensis: 8, 41, 67, 69, 199 (Stenzelia) ellipsis: 70 perplana : 64, 70 (Subgenus?) lisbonensis: 69 ovalis: 69 Pacific: 160 coast: 121 Slope of North America: 66 Pacificor: 107 mulleri, Venericardia: 107 turneri, Venericardia: 107 Venericardia: 107 Pakistan: 106, 160 Paleocene: 45, 50, 56, 82, 100, 102, 106, 107, 117, 141, 165, 166, 177, 178 Paleontological Museum, Cornell University: 63 Paleontological Research Institution: 42, 58, 66, 80 Paleozoic: 81 Palmer, Katherine Van Winkle: 9, 15, 39, 42, 43, 44,46,48,49,58,59,62,63,64,68,69,70,81, 82, 115, 118, 141, 143, 145, 148, 151, 153, 154, 155, 157, 158, 166, 178, 199,203 palmerae: 59 Panama: 48, 177 Bay of: 153 Bocas del Toro Island : 53 pa pyria: 122 Kymatox: 125 Lutraria: 125, 126, 130, 131, 180 Pteropsis: 125 mooreana, Tellina: 121 Pteropsis: 130, 132, 180 Tellina: 121, 208 papyrius, Kymatox: 8, 128, 131-132, 209 Paris, France: 73, 86, 91, 102, 108, 110, 118, 120, 123, 142, 154, 165 Basin: 64, 83, 84, 91, 102, 106, Ill, 142 parisiensis, Pitar (Cal pi taria ) : 141, 210 Parnes, France: 142 Parona, : 64 Patagonia: 92 Patterson, J. M.: 97, 157 pebbles: 22 Pecten: 87 calvatus: 85, 86, 129 claibornensis: 84, 85 corneus: 83, 84 ( Eburneopecten) scintillatus: 84 fragilis : 87 lens: 83 (Pseudamusium) scintillatus: 84 scintillatus: 84 corneoides : 84, 85 pectinata, Nucula (Pectinucula) : 45 Pectinicae: 41, 82-86 Pectinidae: 84 Pectinucula: 45 pectinata, N ucula: 45 ripae, Nucula: 45 pectuncularis, Pachecoa? : 70 Pectunculus auritus: 71 corbuloides: 70 decisus: 65 ellipsis: 64 perplanus : 64, 72 pellets: 30, 31 faecal: 30, 31 pencil shales: 22 Pendleton: 58, 59 formation: 59 Pennant, : 26 Pen. & Dumble: 151 Penrose, R. A. F., Jr.: 14, 151 Pennsylvania, Philadelphia: 49, 101, 104 perantiqua, Venericardia: 111 Percilla, Houston County: 147, 215 -Grapeland road: 147, 215 rock flat near: 146 periostracum : 27 Permian: 83 Perna texana: 39 Pernidae: 75 Peron, : 107 Peronidia, section: 122 papyria, Tellina: 121 perovata, Abra: 119 perlana, Halonanus (Triacriella): 64 Limopsis: 71, 72 Pachecoa (Stenzelia): 64, 70 perplanus, Limo psis: 72 Pectunculus: 64, 72 perplicata, Cubitostrea: 68, 95 lnoperna: 74, 75 Persia: 75 Persian Gulf: 160 Perthes, Justus : 97, 120 petropolitana, Abra: 8, 41, 118, 119-120, 204 Arca:8,41,56-57,198 Calorhadia ( Litorhadia) : 8, 41, 50-51, 197 Cubitostrea: 8, 41, 94-95, 100, 204 Diplodonta: 8, 34, 41, 116, 117-118, 201 Glycym.eris: 8, 41, 60-61, 198 Lima (Lima tul ell a) : 8, 88, 201 Pholadomya: 9, 27, 29, 41, 163-164, 211, 212 Pteria: 8, 41, 81, 200 Syndosmya: 119 Tellina (Moerella) : 8, 41, 123-124, 215 Vokesula smithvillensis: 9, 21, 41, 173, 176, 214, 215 petropolitanus, Pitar ( Calpitaria) : 9, 41, 143-145, 147, 148, 150, 210 petrosa, Con., Lutraria (Pteropsis): 129 Greek: 127 Lutraria: 126, 127 Peyrot, A.: 160 pharcida, Calorhadia: 46, 48, 49 Leda: 46 Pharomytilus: 75 Phenacomya: 165 Philadelphia, Pennsylvania: 15, 42, 78, 101, 107, 108, 110, 126, 130,155,165 Acaden1y of Natural Sciences of: 11, 40, 41, 49, 65, 93, 101, 104, 109, 111, 113, 114, 115, 122, 127, 128, 132, 15~ 172, 201, 208,209 Philippi, E.: 83, 89 Phillips, Mrs. Venia T. : 42 Pholades: 161 Pholadomya: 7, 27, 162, 164 candida: 161 claibornensis: 164 harrisi : 162, 163 cuneata: 165 harrisi: 9, 162-163, 164, 165, 211, 212 leonensis: 9, 41, 163, 164-165, 211, 212 marylandica: 164 mauryi: 165 petropolitana: 9, 27, 29, 41, 163-164, 211, 212 Sowerby: 161-165 Pholadomyidae: 161-165 Pholas: 161 phosphorite concretions: 165 phylogenetic arrangement of rotunda-alticostata stock: 113 Pictet, : 75 Pictet &Cam piche: 7 5 Piedmont of Italy: 116 Piemonte: 87, 91, 95 Pilshry, H. A.: 42 Pinna: 78, 80 gravida: 79 harnetti : 80 nigra: 78 vexill um : 78 Pinnicae: 41, 78-80 Pinnidae: 26, 78-80 Pinoak Creek, Bastrop County: 90, 114, 149, 201 Pissarro, G.: 84 Pitar: 137, 141 Adans.: 140 californianus: 148 ( Calpitaria) : 142 citrinus: 142 parisiensis: 141, 210 petropolitanus: 9, 41, 143-145, 147, 148, 150, 210 sulcatarius: 141 texacola: 9, 144, 145-147, 148, 211, 215 texibrazus: 41, 143,147-148,211 tornadonis: 9, 144, 145, 148-151, 210 transversus incurva tus: 143 (Pitar) tumens: 140, 215 (Pitarina) citrinus: 142 Romer: 135, 140-151 s.l.: 153 S.S.: 142 Pitaria: 133, 142, 153 astartoides : 155 Dall:. 135 ( Katherinella) arnoldi : 133 ( Lamelliconcha) : 39, 155 (Pitaria) texacola: 143, 145, 148 ( Rhabdopitaria) astartoides: 151, 155 Pitarina: 142 citrinus, Pitar: 142 Pitarinae: 133-161 Plaisarlcian, Pliocene, of England: 177 Planicosta, Ca~dita: 129 densata, Venericardia (Venericor): 8, 9, 99, 100, 103-104, 204 planicosta, Venericardia (Venericor) : 102 Venericardia: 102, 106 ( Venericor) : 104, 115 planus, Ectinochilus texanus: 203 plate headings of Bruguiere: 86 Pleasanton : 96, 205 Pleistocene: 170 plicata, Inoperna: 75 Litorhadia: 51 Modiola: 75 Pliny: 161 Pliocene : 116, 170 Plaisancian, of England : 177 plugs, byssal: 9, 201 Plummer, F. B.: 15, 69, 137 P. nigra: 78 Polinices aratus: 199 Polk County, Corrigan: 146 polychaete annelid worms : 7, 30 Polydora: 207 ponderosa, Exogyra: 7 4 Pooser' s Hill : 63 Popenguine, Senegal, Africa: 107 Popenoe, \V.P.:74, 75 Pope's Creek, Charles County, Maryland: 48, 100 population densities: 29 Porch, E. L., Jr.: 157 Poromyicae: 41, 177-180 Porter survey, Burleson County: 10 Porters Creek formation: 50, 177 Port Royal, Virginia: 48 position of the umbo: 41 potomacensis, Calorhadia: 48 . Nucula: 46 Potomac River: 46 Powell tract: 165, 211, 212 praecompsa, Calorhadia: 41, 48, 49, 197 praelapidosus, Kymatox: 8, 9, 27, 29, 41, 124, 128, 132-133, 208 Prague: 80 pre-Linnean name: 90 Pressler, C. \V.: 10 Pressler &Langermann: 10 ·Prestwood Bridge: 68, 199 Price, W. A.: 43, 44, 68, 69, 153, 155, 157, 158, 166 Price &Palmer: 43, 44, 68, 69, 153, 155, 157, 158, 166 pricei, Rhabdopitaria: 155, 157, 158 Prince Georges County, Maryland: 117 Prionodontida: 55-73 prismatica, Abra: 33 proof sheet, Conrad's plate 20: 154 prona, Cubitostrea: 91 prono, Ostrea: 91 Protobranchia: 43-55 ( Protosurcula) gabhii, Turricula: 21 psammotaea orangehurgensis, Orthoyoldia: 55 Orthoyoldia: 8, 53, 54-55, 197 sensu lato : 55 vivianensis, Orthoyoldia: 55 Yoldia (section Orthoyoldia) : 54 P. scintillatus, nob. : 82 Pseudamusium: 83 scintillatus, Pecten: 84 Pseudamussium claibornense: 85 scintillatus, Amusium: 84 Pseudentolium: 83, 84 pseudo£ aeces: 30 Pseudolamellibranchia: 73-101 Pseudoliva carinata: 204 Pteria: 81 argenta: 82 deusseni: 82 hirundo: 80 limula: 82, 200 vanwinkleae: 82 (Pteria) petropolitana: 8, 41, 81, 200 Scopoli: 80-82 sensu stricto : 81-82 Pteriacea : 7 5 Pteriicae: 41, 80-82 Pteriidae: 80-82 Pteropsella : 180 Pteropsis: 125, 180 Conradi: 126 conradi: 127 harrisi : 127, 128 lapidosa: 126,127, 129,132 papyria : 130, 132, 180 ( Lutraria.) : 125 petrosa, Con., Lutraria: 129 pulcher, Halonanus: 62, 63, 64, 66 pulchra: 66 Noetia: 62 Pachecoa: 8,65-66,69, 199 Noetia: 65 sabinica, Trinacria : 66 Trinacria: 64, 65, 67 pulchrus, Halonanus: 65 punicea, Tellina: 120 ( Eurytellina) : 120 pyrite : 24, 32 Pyrula: 129 quadrangularis, V erticordia ( Haliris) : 179 Quaritch, Bernard : 87 Quaternary: 174 Queen City formation: 9, 44, 55, 68, 69, 153, 157, 158, 168, 199 sand: 151 species : 155 Quenstedt, Werner: 27, 45 Quitman, Jackson Parish, Louisiana: 155, 180 Quitman-Liberty Hill road : 155, 180 radiata B., D., & D.: 169 Tellina: 120 Radula ( Ctenoides) scabra: 89 inflata: 87 Rafinesque, C. S. : 125 raindrop imprints: 33 Rathbun, M. J. : 15 Rattlesnake Hill: 63, 199 Recluz, C. A.: 119 Red Bluff clay: 178 Red Bluff, Wayne County, Mississippi: 178 Redland: 159, 172, 211 quadrangle: 159 Red Land;La. : 39 Redlands Church: 128, 133 Red Sea: 78, 86, 87, 159, 160 reefs: 31, 33 oyster: 3~35 Reeve, L. A. : 159 reginajacksonsis, Calorhadia: 48, 49 regional disconf ormity: 10 Reinhart, P. W. : 56, 57, 62, 66 Reklaw formation: 55, 137, 174 Renick, B. C.: 14, 18, 20, 23, 43, 47, 51, 52, 54, 58, 65, 66, 67, 76, 84, 94, 95, 98, 100, 114, 121, 127, 132, 143, 145, 148, 160, 162, 163, 166, 171, 174, 176 Renick & Stenzel: 14, 18, 20, 23, 43, 47, 51, 52, 54, 58, 65, 66, 67, 76, 84, 94, 95, 98, 100, 114, 121, 127, 132, 143, 145, 148, 160, 162, 163, 166, 171, 174, 176 Rhabdopitaria: 9, 141, 153, 154 astartoides: 9, 139, 151, 152, 153, 154, 155-158, 211. Pitaria: 151 discoidalis: 155 Palmer: 151-159 pricei : 155, 157, 158 subcrassa: 155, 157, 211 texangelina: 9, 41, 155, 158-159, 211 winnensis: 155 Rhode Island: 177 rhomboidea, Crassatella : 129 rib count: 181 Richards, H. G. : 42, 80 Richardson survey: 77, 200 Rio Bravo Oil Company: 42, 97, 157, 211, 212 Rio de Janeiro, Brazil : 53 Rio Grande: 47, 51, 54, 75, 98, 121, 136, 145, 151, 153, 155, 157, 166,174 embayment: 52 ripae, Nucula (Pectinucula?): 45 Ripley formation: 74 Risso, : 116 Rittenberg, S. C. : 32 river channel : 25 River Road: 129 Robbins: 128 depot: 165, 211, 212 Robertson County: 11, 20, 114, 115 -Brazos County line: 115, 207 robinaldina, Lima ( Ctenoides) : 89 Robinson County, Cedar Creek in: 146 rocana, Cubitostrea: 92 rock flat, near Percilla, Houston County: 146 Rock Color Chart: 20 Romer, Eduard: 135, 140 Roemer, Ferdinand: 7, 11, 14, 74 Rollier, Louis: 75 rosea Brown: 169 Rosefield, Catahoula Parish, Louisiana: 80 rotunda-alticostata stock: ll3, 115 phylogenetic arrangement of: 113 rotunda Lea, Mut.: 110 Mut.: 108 Venericardia: 113 rotundata, Diplodonta: 115 Tellina: 115 Venus: 115 rubamnis, Orthoyoldia: 53 rudimentary organ: 107 ruf a, Anomia: 100 rugae: 153 rugosa, Corbula : 174 rugose nymphs: 153 Rusk-Crockett county road: 76, 150, 200, 210 Rutsch, Rolf: 9, 102, 106 Rutsch & Schenck: 9, 106 Sabine County: 59, 62, 66, 68, 96, 162, 198, 199 Sabine Parish, Louisiana: 61, 66, 96, 100, 198, 199 Sabine River: 7, 20, 34, 52, 54, 58, 59, 62, 84, 96, 103, 114, 172, 180, 198, 199 township line: 66 Sabinetown : 62, 68 marl: 62, 66 sabinensis, Glycymeris: 60, 61, 66, 198 sabinica, Pachecoa: 8, 61, 66, 69, 199 Trinac:fia pulchra: 66 Sacco, Federico: 86, 87, 91, 92, 95 Sagra, Ramon de la : 177 salinity: 31, 35 Salisbury, A. E.: 120 Sambarieto Creek: 151 San Antonio: 11, 12 Ferry: 10 Geological Society: 157 San Augustine: 93, 94, 203 County: 93, 94, 171, 203 sanctiaugustini, Cubitostrea: 8, 41, 93-94, 95, 203 San Diego: 170 San l\'liguel Creek : 96 San Pedro Chapel: 150, 200, 210 Santa Ana Mountains: 7 4 Santa Barbara farm: 151, 1E6 Santa Elena Canyon: 75 santanensis, Corbula ( Caryocorbula) : 166 Santee limestone: 8, 84, 85, 130, 208 Santee River: 129, 130, 208 Santee-Vance-Eutaw Springs road: 129 Sassi, A. : 71 satex, Diplondonta: 117 Verticordia : 178 (Trigonulina): 9, 177-180 Savy, F.: 120, 123 Say, : 131 scahra Born : 90 L.: 89 Lima ( Ctenoides) : 89 Ostrea: 89 Radula ( Ctenoides) : 89 sea pina, Orthoyol dia: 53 scapania, Orthoyoldia: 53 scaphopods: 7, 31 scar, attachment: 203 scattergram: 181 Schenck, H. B.: 9, 27, 106 Schmidt, F. C.: 97, 120 Schuchert, Charles: 179 Schulze, F. E.: 89, 90 Schweizerbart, E.: 108, 110 scintillatus, Amusium ( Pseudamussium) : 84 Camptonectes: 84 Chlamys ( Camptonectes) : 84 corneoides, Pecten: 84, 85 Eburneopecten: 8, 82, 83, 84-86, 200, 203 Pecten: 84 ( Eburneopecten) : 84 (Pseudamusium) :. 84 P., nob.: 82 Scopoli, J. A. : 7 4, 80 sculpture, allomorphic: 9, 98, 99, 101, 201, 203, 204 Scutella bed: 179 Seattle, Washington : 133 secans, M ut. : 108 Secans De Greg., Mut.: 110 section Peronidia: 122 sedis, lncertae : 127 Seine et Oise, France: JOI, 102, 141, 210 sellaef ormis, Cubitostrea: 130 divaricata, Ostrea: 92 Ostrea: 92, 94, 128, 129, 130 stock: 91, 92 sellardsi, Anomia: 100 Selma-Oakhill road : 177 Semelidae: 118-120 semilunata, Ostrea: 92 seminuda Lam.: 78 Senegal, Africa, Popenguine: 107 Senlis, France: 91 septarian : 24 Septibranchia : 177-180 Sequanian : 7 4 serica, Orthoyoldia: 53 shales, pencil : 22 Sharp, : 75 shark teeth : 34 shell, height and width of: 40 Shell Bluff, Burke County, Georgia: 97 Shell Petroleum Corporation: 42 Sherborn, C. D.: 115 Shetland Islands: 97 Shiloh: 19 cemetery: 20 Shipp's Ford, Fayette County: 149, 150, 210 Lake: 150 Shubuta, Clark County, Mississippi: 79, 82, 200 Shumard brothers: 40 G.G.: 40 Sicilia : 125 Silimani: 108 Mut.: 108 Sillimani Lea, Mut.: 110 sillimani, Venericardia: 109 ( Claibornicardia) : 8, 106, 107, 110-111, 112, 206, 207 Silurian: 81 Sims Siding, Yazoo City, Mississippi: 118 Sinodia: 160 ( Coriopsis) suborbicularis: 160 Jukes-Browne: 159-161 (Sinodia) eocaenica: 9, 41, 160-161, 206 S.S.: 160 trigona: 159 DoRinia: 159 siphon, exhalant and inhalant: 27, 28, 30 Sjaelland, Denmark: 170 slickensided marl: 23 Smithsonian Institution: 11, 101, 108, 110, 172, 173 Smithville: 8, 9, 45, 48, 49, 52, 55, 67, 69, 85, 88, 90, 135, 136, 137, 145, 147, 151, 155, 157, 166, 167, 168, 171, 173, 176, 181, 197, 199, 201, 209, 210, 213, 214 -Bastrop road: 199, 201, 209 -La Grange road: 150, 210 quadrangle: 114 -Winchester road: 90, 114, 201 smithvillensis: 175 Corbula: 174, 176 aldrichi: 173, 174 (Varicorbula) : 17 4, 176 Cu.bitostrea: 89, 197 Katherinella: 9, 41, 135-137, 148, 209 Lima (Limatulella): 8, 41, 88-89, 201 Nucula: 41, 44-46 ( Nucula) : 8, 197 Pachecoa: 8,41,67,69, 199 petropolitana, Vokesula: 9, 21, 41, 173, 176, 214, 215 Vokesula: 9, 21, 42, 173, 174-176, 214 statistical analysis of: 181-186 snails, naticoid : 199 Snow Hill calcareous member: 7 4 Snow Hill, North Carolina : 7 4 solea, Eburneopecten: 83 soleniscus, Ostrea: 95 solenoides, Orthoyoldia: 53 Somaliland: 126 Sornay, : 107 Sornay &Tessier: 107 sotoensis, Verticordia (Trigonulina) : 178, 179 South America: 121 South Carolina: 8, 42, 84, 120, 127, 130 Columbia: 80, 126 Orangeburg: 55, 62, 63, 70, 76, 127, 128, 129, 199 Columbia Road: 80 County: 55,63,86, 199,208 District: 43 Vance: 129, 208 Vance's Ferry : 127, 128, 129 white limestone of: 101, 201 Southern Railroad: 113, 179, 198 Southern Pacific Railroad: 10, 16 sowerbianus, Mitylus: 75 Sowerby, G. B.: 48, 87, 161 Sowerby,J.: 74, 75,83,84 J. de C.: 143, 177 James: 87 Sowerby, : 46,47,92, 160, 165 sowerbyanus, Mitylus: 75 Soyer, Robert: 91 Spanish edition : 177 Sparnacian: 142 Sparta formation: 25 sand: 7, 18, 19, 20 Spathella-shape: 73 Sphaerella: 116 sp.: 117 spheniopsis, Nucula: 46 spiral structure: 7 Spix, : 116 Spooner, G. M.: 33 Spooner & Moore: 33 Spout Springs, Harnett County, 'North Carolina: 80 . Sprunt or Highland Farm: 80 squamosissima Phil: 78 squids: 7, 31 staminea, Glycymeris: 61 standard deviation: 181, 184, 185 standard error: 184, 185 Starr County : 51 State Reclamation Department: 16 topographic map: 10 State Geologists of Texas: 39, 40 State Highway Department: 11 State highway numbers­ 6: 129 7: 165 10: 177 15: 112, 208 21: 10 71: 45, 49, 52, 67' 88, 137' 150, 168, 173, 176, 197, 199,201,209,210,213,214 100: 177 statistical analysis: 9, 181-186 Stenzel, H. B.: 8, 9, 14, 15, 18, 20, 21, 23, 24, 27, 29, 34, 38, 39, 41, 42, 43, 46, 47' 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 63, 65, 66, 67' 68, 69, 70, 71, 76, 77' 78, 79, 81, 84, 88, 90, 91, 92, 93, 9~ 95, 98, 99, 100, 104, 105, 112, 114, 116, 117, 118, 119, 121, 122, 123, 124, 127, 128, 129, 130, 132, 133, 135, 137, 138, 139, 143, 144, 145, 146, 147, 148, 150, 153, 154, 155, 157' 158, 159, 160, 162, 163, 164, 165, 166, 171, 172, 173, 174, 176, 179, 180, 197' 198, 199, 200, 201, 202, 203, 204, 205,206, 208, 209, 210,211, 212,214,215 Stenzel & Krause: 8, 9, 27, 29, 41, 42, 48, 49, 50, 52, 53, 56, 58, 59, 77, 10~ 105, 123, 124, 126, 128, 132, 133, 135, 137, 138, 139, 143, 144, 145, 147, 148, 150, 155, 1E8, 159, 160, 197, 198,200,206,208,209,210,211,215 Stenzel & Turner: 15, 69, 157 Stenzel & Twining: 8, 9, 21, 27, 29, 41, 43, 46, 60, 65, 67, 68,69,81, 88, 90, 93, 94, 95, 100, 163, 164, 173, 176, 197, 198, 199, 200, 201, 203, 204,211,212,214,215 Stenzelia : 64 ellipsis, Pachecoa: 70 Halonanus: 72 perplana, Pachecoa: 64, 70 Stephenson,L. W.:40,74,75 Stewart, R. B.: 9, 46, 49, 50, 62, 64, 83, 101, 102, 106, 116, 135, 162 St. Francis County, Arkansas: 62, 70 St. Johns channel : 33 St. Matthews quadrangle: 63 St. Maurice, Winn Parish, Louisiana: 79, 113, 128, 162, 180 St. Maurice clays: 54 St. Maurice stage: 14, 43, 47, 51, 54, 61, 65, 66, 67, 72, 73, 75, 78, 84, 92, 95, 108, 110, 111, 114, 121, 127, 130, 143, 145, 148, 162, 166, 171, 174, 176 Stoliczka, Ferdinand : 7 4 Stone City: 10, 16, 19 beds: 59 Strong, A. ·M.: 9, 47, 48, 120, 153 Stuttgart: 108, 110 subcrassa, Cytherea : 153, 154, 155 Rhabdopitaria: 155, 157, 211 subfamily: 38 new: 41 subgenera, new=~41 suborbicularis, Sinodia ( Cordiopsis) : 160 Venus: 160 suborder: 38 subquadrata, Cardita: 114 V enericardia : 111 substratum: 98 subtaxa: 38 Suffolk, England: 177 sulcataria, .Callista: 141 Cytherea: 141 sulcatarius, Pitar ( Calpitaria) : 141 sulfides: 7, 32 sulfur: 32 acids: 22 sulfuric acid : 22 Sulphur Springs School : 77, 200 superfamilies, new endings of: 41 superfamily: 38 superorder: 38 su pertaxa : 38 suspension feeder: 27 Syndosmya: 119 (Syndosmya) petropolitana: 119 synthesis: 35 Takahashi, Jun-Ichi: 30 Takahashi & Yagi: 30 Tallahatta formation: 8, 91, 95, 199 Tamar estuary: 33 Taras: 116 tarentina, A vicula : 80 taxa: 38 T. donacina : 123 Tebo Bayou, Sabine County: 162 tecta, Lima ( Ctenoides) : 89 teeth, shark : 34 Tegland, N. M. : 133, 134, 135, 138 Tehuacana member: 117 Tejon formation: 148 Tellina: 7 (Eurytellina) mooreana: 8, 121-123, 208 punicea : 120 gibba: 170 Linne: 120-124 ( Moerella) donacina: 123 petropolitana: 8, 41, 123-124, 215 mooreana: 115, 121, 122 Mooreana: 121, 122 olimpica: 170 papyria: 121, 208 mooreana : 121 (Peronidia?) papyria: 121 punicea : 120 radiata : 120 rotundata: 115 ten uis : 28, 29 Tellinicae: 41, 118-124 Tellinidae: 29, 120-124 tenera Ch. : 90 Tenidah, Plateau of: 102 Tennessee: 165 Coon Creek: 7 4 ten uis, Abra : 118 Amphidesma: 118 Mactra: 118 Tellina : 28, 29 Teppner, W. von: 84 Tessier, Fernand: 107 texalana, Venericardia trapaquara: 106 texacola, Cytherea: 144, 147, 151, 211 Meretrix: 143, 145 Pitar (Calpitaria): 9, 144, 145-147, 148, 150, 211, 215 Pitaria: 143, 145, 148 tomadonis, Cythera: 144, 210 Meretrix: 148, 149 texana, Corbula: 114, 169, 170, 171 ( Aloidis) : 171 (Varicorbula) : 171 Modiola: 39 Notocorbula: 159, 170-173, 214 Perna: 39 texangelina, Rhabdopitaria: 9, 41, 155, 158-159, 211 texanum cherokense, Ectinochilus: 203 texanus plan us, Ectinochilus: 203 Texas Geological Survey: 42, 52, 136, 147, 150, 151, 163, 176 Texas State Museum: 76, 96, 114, 163 texibrazus, Pitar (Calpitaria): 41, 143, 147-148, 211 texitrina, Katherinella?: 9, 41, 138-140, 209, 215 Thailand: 159 Thanetian: 142 Therrill formation: 20 threadlets, vermiculate: 132 Three-Mile Bayou: 76, 200, 210 tidal currents: 35 Tinctora : 153 vulnerata: 153 Tombigbee River: 46, 50, 117, 174 topographic map, State Reclamation Department: 10 topotype : 38 Torino: 87 tornadonis, Callocardia (Agriopoma) : 148 Cytherea texacola: 144, 151, 210 Meretrix texacola : 148, 149 Pitar ( Calpitaria) : 9, 144, 145, 148-151, 210 Torrey brothers: 11 torsion : 143 Tortola Island: 161 Totha: 97 Toutelot, H. A. : 82 Town Branch: 11, 207 township line, Sabine River: 66 track-like imprints: 197 transversa: 110 Cardita: 108, 110 (Venericardia): 108, 110 incurvatus, Pitar ( Calpitaria) : 143 Venericardia: 107, 108,.109 trapaquara texalana, Venericardia: 106 Venericardia ( Claibornicardia) : 8, 34, 106, 107, 113, lltir-115,207 Treatise on Invertebrate Paleontology, Committee on Pelecypoda of: 38 Tremlett, W. E.: 142, 143, 160 Trent marl: 84 (Triacriella) cossmanni, ·Halonanus: 72 trigona, Artemis: 159 D.: 159 Dosinia ( Sinodia) : 159 Sinodia: 159 Trigonarca : 64 trigonella, Glycymeris: 60, 61, 198 trigoniata: 136 bastropensis, Meretrix: 136, 137, 160 Cytherea: 154, 155 Katherinella: 138, 155 Trigonocoelia aurita: 71 Trigonulina: 178 cossmanni, Verticordia : 179 crassa: 64 dalliana, Verticordia : 178 D'Orbigny: 177-180 ornata: 177 V erticordia : 177 satex, Verticordia: 9, 177-180 sotoensis, Verticordia : 178, 179 Trinacria : 63, 64, 70, 72 cossmanni: 71, 72 crassa: 64 cuneus: 70 decisa: 65 abbreviata: 69 carolina: 70 declivis: 66 ovalis: 63 ( Pachecoa) cainei: 62 perplana: 64 pulchra : 64, 65, 67 sabinica: 66 Trinacriella: 64 perplana, Halonanus: 64 Trinidad Island, West Indies: 89 trinitatis, Katherinella: 9, 41, 137-138, 139, 209 Trinity Church: 63 Trinity River: 51, 115, 137, 138, 140, 152, 153, 155, 156, 157, 158,209,211,215 Alum Bluff on: 146 tripartite costae: 105 Trowbridge, A. C.: 47, 51, 52, 54, 98, 106, 121, 132, 151, 154, 156,157,166, 174 tuberculata, Lima ( Limatulella) : 87 Tucker-Rowland, H. I.: 84, 86 tumens, C.: 140 Pitar: 140, 215 Venus: 140 Tunisia: 103 Tuomey, Michael: 101, 126, 127, 129, 130 Turbinolia: 31, 33 Turkey Hill Branch: 63, 199 Turner, F. E.: 15, 69, 148, 157 turneri, Venericardia ( Pacificor) : 107 Turner's place: 155 Turricula (Protosurcula) gabbii: 21 Twining, J. T.: 8, 9, 21, 27, 29, 41, 42, 43, 46, 60, 65, 67, 68, 69, 71, 81, 88, 90, 93, 94, 95, 100, 148, 163, 164, 173, 176, 181, 197, 198, 199,200, 201,203,204,211,212,214,215 type locality: 39 . Tyus member: 94, 106, 146, 147, 165, 203, 211, 215 survey, Leon County: 211, 212 umbo, position of: 41 ungulina, Diplodonta: 118 yazoocola, Diplodonta: 118 uniform endings: 38 Union Pacific Railway: 133 University of Houston: 41 Upper Albian: 7 4 Upper Eocene: 82 Upper Greensand: 74 Upper Landing: 43 Upper Lias: 75 Upper Marlboro, Prince Georges County, Mary­land: 117 U.S. Geological Survey: 63, 66, 114, 129, 147, 150, 151, 159 grain-size field kit: 21 U. S. highway numbers­ 11: 113, 179, 198 ·21: 63, 199 31: 199 59: 1!19, 172,211 178 By-pass: 63, 199 190: 61 U.S. National Museum·: 55, 154, 157 uxorispalmeri, Barbatia: 8, 41, 42, 58-59, 100, 198 Valmondois, France: 91 Valudayur group: 74 valve, inflation of: 40 Vance-Eutaw Springs-Santee road: 129 Vance, South Carolina: 129, 208 Vance's Ferry, South Carolina: 127, 128, 130, 208 Van Winkle, Katherine E. H.: 127, 128 vanwinkleae, Pteria limula: 82 variability, coefficient of: 185 limits of: 185 Bureau of Economic Geology, The University of Texas Varicorbula: 9, 169, 170 gibba: 170 smithvillensis, Corbula: 174, 176 texana, Corbula.: 171 Vaughan, T. W.: 14, 33, 114, 127, 166, 171 Veatch, A. C., locality 21 of: 61, 66, 199 locality 22: 61, 198 locality 23 : 96 Venericae: 41, 133-161 Venericardia alticostata: 108, 109, 110 group: 106 ( Baluchicardia) : 9 ameliae popenguinensis: 107 beaumonti: 106 bulla: 107 baronneti: 102 blandingi : 129 ( Claibornicardia) : 9 alticostata: 8, 9, 104, 105, 107-109, 111, 112, 206, 207 acuticosta: 106, 107, 111 complexicosta: 8, 106, 107, 111-114, 208 sillimani: 8, 106, 107, 110-111, 112, 206, 207 trapaquara: 8, 34, 106, 107, 113, 114-115, 207 densata: 104, 208 bed: 55 hadra: 106 hesperia: 106 imbricata: 101 Lamarck: 101-115 Mooreana: 103, 104, 111 mooreana: 104, 112, 113, 204 nasuta: 106 (Pacificor) : 107 mulleri: 107 turneri: 107 perantiqua: 111 planicosta: 102 group: 106 rotunda: 113 sillimani: 109 subquadrata: 111 transversa: 107, 108, 109 Cardita: 108, 110 trapaquara: 114 texalana : 106 (Venericor) claiboplata: 104 duponti: 102 planicosta densata: 8, 9, 99, 100, 103-104, 115, 201, 204 planicosta: 102 wegeneri: 102, 103 Venericor: 102 claiboplata, Venericardia: 104 densata, Venericardia: 103 duponti, Venericardia: 102 planicosta, Venericardia: 104, 115 densata, Venericardia: 8, 9, 99, 100, 103­104, 201, 204 planicosta, Venericardia: 102 Stewart: 101-104 Veneridae : 126, 133-161 Venezia : 170 Venus: 140 imbricata: 101 incrassata: 160 lupinus: 115 rotundata: 115 suborbicularis: 160 tumens: 140 Verastegui, Pedro: 107 vermiculate threadlets: 132 vermilla, Mu t. : 92 Verrill, A. E. : 53, 54 Verrill &Bush : 53 Verticordia : 177-180 cardiif ormis: 177 eocoensis, Langdon: 179 ( Haliris) mississippiensis: 179 quadrangularis : 179 satex: 178 sp.: 177, 178 S.S.: 179 ( Trigonulina) cossmanni: 179 dalliana : 178 ornata: 177 satex: 9, 177-180 sotoensis : 178, 179 ( Verticordia) eocoensis : 179 V erticordiidae : 177-180 vexillum, Pinna: 78 vicaria, N otocorbula : 168, 170 Vicksburg group: 53, 80, 82, 119, 174, 178 specimen : 78 Vicksburg, Warren County, Mississippi: 80, 82, 119, 126, 174 Viesca member: 45, 49, 52, 55, 59, 67, 88, 106, 123, 135, 147, 165, 168, 173, 176, 181, 182, 183,197, 199,201,209,211,212,213,214 Vincent, Emile: 84 virginica, Crassostrea : 95 Ostrea: 95 Virginia, Aquia Creek: 164 Evergreen: 117 King George County: 46 Newcastle: 128 Port Royal: 48 virginiana ( Gmel.) , C. : 95 Virgin Islands: 161 Vivian, Caddo Parish, Louisiana: 55 vivianensis, Orthoyoldia psammotaea: 55 Vokes, H. E.: 38, 165, 169, 170, 174, 180 Vokesula: 9, 41, 17 4 laqueata: 174 smithvillensis: 9, 21, 42 petropolitana: 9, 21, 41, 173, 176, 214, 215 smithvillensis: 9, 173, 174-176,214 statistical analysis of: 181-186 Stenzel & Twining: 173-176 Volsella : 74, 77 Von Buch, Leopold: 11 vulnerata, Cytherea Brod.: 153 Tinctora: 153 Waco Landing: 129 Wade, Bruce: 74,75 wailesiana: 175 '\Va]ker Creek: 61 Wallace, W. E., Jr.: 55 Walnut formation: 74, 75 Warren County, Mississippi: 80, 82, 119, 174 Washington : 138, 148 Lewis County: 133 Seattle: 133 Washington County, Alabama: 56, 107, 117 wautubbeana, Glycymeris: 60, 61, 198 Wautubbee, Clarke County, Mississippi: 60, 111, 112, 113, 179, 198 formation: 198, 208 Hills: 178 wave action : 34-35 waves: 35 Wayne County, Mississippi: 178 Wealthy, Leon County: 19, 20 Weaver, C.-E.: 92, 133, 134, 135, 138, 148 Webb County: 97, 151, 156, 157 -Zapata County line: 145 Weches formation: 8, 9, 20, 44, 45, 48, 49, 52, 53, 55, 59, 62, 67' 83, 85, 86, 88, 90, 93, 94, 95, 100, 104, 105, 106, 107' 123, 125, 128, 133, 134, 135, 136, 137, 145, 146, 147, 149, 163, 164, 165, 168, 173, 176, 181, 182, 183, 197' 199,201,203,209,211,212,213,214,215 member: 163 sample: 184 wegeneri, Venericardia: 102, 103 Wells, J. W.: 33 Western Texas: 168 West Indies: 89, 161 West Muds: 33 Wheelock marl member: 7~ 11, 19, 20, 22, 59, 61, 73, 76, 77, ·79, 114, 117, 123, 137, 145, 148, 173, 181,182,184 Wheelock, Robertson County: 11, 19, 101, 104, 115 Wheelock survey: 115, 207 Whitbian: 75 White Bluff, Jefferson County, Arkansas: 52 White, J.: 116, 118 white limestone of S. Carolina: 101, 201 Whitney, F. L. : 42 width of a shell : 40 Wilcox County, Alabama: 177 Wilcox group: 46, 47, 48, 50, 55, 56, 59, 62, 68, 83,85,90, 100,107,113, 117, 164,174 Wilson tract: 77, 200 Winchester: 90 Smithville road: 90, 114, 201 Winckworth, R. : 26, 27, 78, 87 winnensis, Rhabdopitaria: 155 Winnfield, Winn Parish, La. : 91 Winn Parish, Louisiana: 79, 91, 155, 180 Wood, Searles V.: 83, 91, 177 Wood, "\V.:28,30,31 Woodbine group: 40, 95 W oodbluff, Alabama: 46, 50 Woodring, C. W.: 134, 135 Woodring, Wendell P.: 42, 53, 116 Wood's Bluff, Clarke County, Alabama: 46, 48, 50, 100, 174 Woods, Henry: 74, 75 Woodstock member: 46, 100 Woodstock plantation: 46 worm boring: 207 worms, maldanid polychaete annelid: 7, 30 Xenocrates Medicus: 60 Xenohelix: 30 xyloid lignite: 22, 24, 25 Yagi, Tsugio: 30 Yazoo clay: 118 Yazoo City, Yazoo County, Mississippi: 118 yazoocola, Diplodonta ungulina: 118 yazooensis, N ucula magnifica : 46 Yegua formation: 97 -Cook Mountain boundary: 97 Yoakum, Prof. : 39 yoakumii, Meretrix: 39 Y oldia aldrichiana: 50 claihornensis : 54 -like: 51 ( N uculana? ) psammotaea: 54 (section Orthoyoldia) psammotaea: 54 S.S.: 53 Yonge,C.M.:27,28,30,33 Young, Keith: 42 Young~Murchison tract: 76 Zapata County: 51, 136 -Webb County line: 145 Zavala County: 157 Zittel, K. A. von: 98 Zoological Nomenclature, International Commis­sion on : 86, 116 Zoology, Official List of Generic Names of: 55 Zwolle, Sabine Parish, Louisiana: 100