TIE ViALi:WT FOillJ.AT ION OF CENTRAL TEXA.S • Approved. : pproved : THE WALNUT FORMATION OF CENTRAL TEXA.S THESIS .Presented to the Faculty of the Graduate School of Th• University of Texas in Partial Fulfill­ment of the Requirements For the Degree of MASTER OF ARTS William Billingslea Milton,Jr.,B.A. Austin, Texas June, 1928 Preface The writer wishes to express his gratitude to Professor F.L. Whitney, under whose supervision this work was done, for his constructive criticism an~ advice, and for his assistance in t~e photo­graphing of the fossils. The reports of Messrs. R.T. Rill, J~A. Taff, W.S. -4,dkins, and. W.M. Winton have been of invaluable assistance. CONTENTS Page Preface ............................... iii Introduct ion ............................. 1 Name .......................... l Character ........................... 2 Areal Distribution .................. 2 StratigraJ?hy ........................ 3 Lithology ........................... 4 Thickness ........................... 6 Paleontology ............................ 17 General statements .................. 17 Descrir:>tion of species .............. 19 Cer:>halopods ••••••••••••••••••••••• 19 Engonoceras pedernalis von Buch ••• 19 Echinoderms •••••••••••••••• ~ •••••• 19 Diplopodia texanum Roemer ....... 19 Enallaster texanus Roemer ....... 2.0 Holectypus planatus Roemer •••••• 21 Pseudodiadema texanum Roemer .... 23 ···:..· 24 Pelecypods ··~····················· Anatj.na w'iitneyi n. sp. ......... . 24 Cucmllaea terminalis Conrad ..... 24 Cyprimeria texana Roemer ........ 25 Cyrena brilli n. sp. ............ 25 Page Exogyra texana Roemer ................. 26 Gryphaea marcoui Hill and Vaughan..... 27 Granocardium al.leni n. sp. • • • • • • •.• • • • • 28 _Homomya cuyleri n. sp. • • • •.• • • • • • • • • • • • 28 _:Modiole. concentrico-costellat2 Roemer.. 28 \ Neithea irregularis B6se .............. 29 Protocardia texana Conrad ••••••••••••• 30 Protocardia wal~utensis n.sp. ......... 30 ~rigonia emoryi Conrad •••••••••••••••• 30 Gastropods .••••.• ••••••••••••••••••••• ~.... 31 Rostellaria _sp. _undet. ................ 31 Rostellari~ sp. undet. ................ 31 Turritella sp. ....................... . 32 Tylostoma sp. ......................... 32 T;ylostoma pedernalis Roemer........... 32 Corals • • • • • • • • . . . . • . . . . . . . . • . . . . • . . . . . . . • • 33 Parasmilia sp. ........................ . 33 Family Lituolidae ......................... 33 Orbitolina walnutensis Carsey ••••••••• 33 Undetermined phylum ••••••••••••••••••••••• 33 ~qrogystis_globularis ~ '}i ebel ........ 33 Bibliography • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 35 Plates .................................... 38 THE WALNUT FORMATION OF CENTRAL TEXAS Introduction The Walnut formation is a co:::iparatively thin formation lyillg at the base of tJ1e Fredericksburg division, and h 2.vin::; its ereatest (levelopcaent in the region tetween the Brazos and the Color~do rivers. it is a. very persistent forme.tion i~_ ..this region, but its lithology changes both laterally and vertical~ ly within short distance~. T:1e fauna is very sLnil2.r to that of the Glen Rose, for ~hie~ it could e~sily • ' I ~ • be mistaken, were it n?t for a few exceptions v111ich will be considered lat~r. As there is such a great similarity betw'3en certain clay members of the G-len Rose and the Walnut, it was Sl..l -;gested by Professor F. L. ';'ihitney that 2. detailed study be made to deter­mine their exact rel2.t ionship. The Walnut formation, sor:ietimes referred. to as the Exogyra texana beds or the Texana beds, v1as first 1 named and described by Dr. R.T. IUll in 1891, after the town of 'iialnut Springs in :Bosque County where he found it most typically exposed.. r- Hill, R.T.: 11 The Co ,11a.nche Series of the Texas-Arkan­sas Region~' Geol. Soc. America, Vol. 2, 1891, J?p.503­ 512. In the area treated. within this paper, the Walnut formation occurs as a bench beloiv the scarp of the Comanche ~iak linestone. It forms a very gentle and easily r:~cognized slope, because of its cha racteristic capping of limestone and its almost total lack of vegetation. In practically all of the regions visited, there has been a noticeable absence of any really characteristic veget ation. The Bosque River i n Bosq~e Cor nty, and the Polans River i n Bell County flow in valleys which ~ave a predominant 1:'falnut base, and snp)ort a mor e or less profitable agricu..:J_ture. In t~1ese valleys one finds the characteristic Walnut at t 11e bottom, wi t':l t!J.e Comanche :Pea~c and ~dwards along the out er margin. Beginnin6 in t 11e Red IU v~~r reg ion of Gr ayson · ,'1d t;oolce CJ>U!'l.ties and following the line of st rilce i n a general south t o southwestward direction to :Bosc1ue arn:t Co.t·,,·..:.::.: ;:;ountie.s, t~1e outcrop widens, attaining its greatest width in these central coun­ties, t hen narrowing southward until t~er'~ a re only a few scattered outcrops , w':lich appes..1· :nerely as benches below the hard.er cap of limestone. In the north cent1·al part of the state, in the Grand Prairie r egion, we find t '-,_e Wa l m:_ t well expos­ ~d>· in a comparatively wide belt, having its great­ est width across Coryell, Bosque, Hamilton, and Co­ manche Counties, and becoming narrower in its expos­ ure and extent as it progresses southward. In the 2 . Geology of Trans-fecos, C.L. Baker states that he finds one hundred feet of Walnut below the overthrust in tne northeast flanl\: of the southern C~uitman Moun­ tains, in the lower part of the Rio Grande Canon across the Q,,uitman Mountains and in the southern part of the Van Horn Mountains. In the University Bulletin by J. W. Beede and. V.v. Waite~ on the geology of Runnels County, there appears a section of Walnut taken near County Line Gap which shows that the formation has an . approximate thickness of fifty feet. Toward the east, the wa1nµt is known from well ,, .~ cores in Mc~ennan County, which show that it has an ayerage thickness of about one hundred feet. Its east­ermost outcrop is in Coryell and Bell oounties, where it forms the. floor of many of the valleys. According to Adkins~. the outcrop of the Walnut covers nearly half the area of Coryell County. r- Baker, C.L.: nExploratory Geology of a part of South­ western Trans-Pecos, Texas, n Univ. of Texas Bull. No. 2745,1927' p.26. -­ 3Beede,J.W. and Waite,V.V.: nGeology of Runnels County, 11 Univ. of Texas Bull. No. 1816,~.4, 1918, p.52. 4I'ffi'ns-;w.s.: "GeoI":"' and Mineral Resources of McLennan County',' Univ. of Texas Bull.Ko.2;)4D,1923,p.31. ·The formation is l{nown as· far south as Medina 5 . ) County, .where it is exposed in the ~nain Balcones Fault zone for about a mile. This e.JCI>osure is on the Tarpley road, sixteen miles north of Hondo, whence it dipl:J steeply to the south and disappears under later formations. In general the Walnut is apparently conformable with both the overlying and underlying rocks; one -notable except ion in "BU.rne{;J County is pointed out ' 6 ·oy Paige. Here the Trinity division is entirely lack­ ~..;~: · ::.' 1ng in certain areas due apparently to non-deposition a.nd the walnut rests on the Ordovician limestone. In the southern part of the Grand Prairie region, begin­ning in Coryell and McLennan Counties, and continuing southward, the Walnut rests upon easily recognized Glen Rose strata, maJcing a definable contact. From McLennan and Coryell ·· Counties northward to Wise Coun­ty, the Walnut rests upon the Paluxy sand, which thins 1 to the southward. ·morthward from Wise County, the Wal­ nut pasaes into the Antlers sand, the upper part of 0-­Liddle,R.A.: "Geel. and Mineral Resources of Medina County," Univ. of Texas Bull., Ho. 1860,1918,p.28. 6 ----­Pa.ige.s.: "Llano-Burnett Folio," Geologic Atlas of . the Unite.d States, 1912, p.9. 5 which at least is thoug!lt to be a phase of the Wal­nut. · The Walnut for:nat ion as a whole consists large­ly of laminated calcareous clays, marly in nature, weathering yellow on exposure, and interrelated with shell agglomerate and semi-crystalline limestone flags. In the central part of the state it grades up almost imperceptibly into the Comanche Peak above, a change being recognizable only in a vertical section of two or three. feet, while further to the sonth the transi­tion is mo~e distinct. There is relatively little or no difficulty en­countered in Central Texas ~n determining the lower contact, either with the Glen Rose~ which in many places is marked by an iron red discoloration, or the Ordovician in Burne~ County, while further north­ward the contact with the Paluxy is not so easily determined nor well agreed upon, but considered by Winton7to be marked by a coarse red sandstone at the contact of the Paluxy1 which is a great contrast in comparison wi_th the overlying lighter and finer graine~ sands considered by him as being the Wal.nut. r- Winton~W.}l.: nGeology of Denton County,n Univ. of Texas B'g.ll. 1 No. 2544, 1925 1 p. 16. In North Texas the top of the Walnut is mark­ed by a shell conglomerate having an average thick­ness of eighteen to twenty-five feet, and made up chiefly of Gryphaea ma,rco:ui. This makes a very per­sistent and easily recognized cap rock, and is used as both a surface and subsurface horizon marker in this area. The lower part of the formation consists of alternating sand, sandstone and clay, and contains 8 the remains of few or no~fossils. Winton, in his bulletin on Denton County, gives the following seo­tio.a in the northwestern part of the county, which will give some idea o.f the Walnut and its overlying format ions. Section No. 1 (Figure 5) Clear Creek Section in Des-oinding Series Dllck Creek: Feet 13. Massive gray limestones contain­ing Hamites fremonti, Hamites co­manchensls, fragments of Desmo::­oeras brazoensis •••••••••••••••• 4.0-- Kiamitia:­ 12. Marls and clays containing many specimens of Gry¥haea navia •••-•• 2.0 11. -Black shales wea hering to yellow­ish brown, containing a few Grypha­ea navia •••••••••••••••••••••••• 20.0 10. 'Sandy !edge containing Schloenbach­ 9. ia belknatii •••••••••••••••••••• Rack sha es weathering t .o yellow­ish brown, containing Exogyra tex­ 1.0 r- Winton, W.M.: "Geology of Denton County~ Univ. !?f Texas~., No. 2544,1925, p.20. ana, Grtphaea marcoui, and Schloen-· '6aChiaelkn~ii••••••••••••••••••••• 5.0 8. Sandstone le e ••••••••••••••••••••• 1.0 7. Black shales containing a few Gryphaea marcoui •••••••••••••••••••• 13.0 Goodland: 6. White massive limestone •••••••••••••• 5.0 5. 111arl s eam ..•....•••.••••••••.••.•••• .5 4. White massive limestone containing Schloenbachia trinitensis ••••••••••• 4.0 3. Thin seams of limestone alternating with marl containing Schloenbachia acutocarinata ••••••••••-••••••••••••• 35.0 Walnut: 2. Shell conglomerate containing vast numbers ofGl;f~haea marcoui, also many Exog~raexana ••••••••••••••••• 16.0 1. White san s, very fine with rounded oval grains, no fossils ••••••••••••• ? 9 In Parker Cou_nty, Taff measured the following section which Hill gives in the Twenty-first Annual 10 Report, and which presents a more detailed descrip­ tion of the character of the Walnut in its northern extent. The section is as follows: Sect ion !To. 13--Hiner, Parleer County, Texast (Taff) Fredericksburg Division / Comanche Peale Formation: Feet 16. Comanche Peak chalky limestone ••••.• 40 15. Chalky limestone with large Exogyra texana, Enallaster texanus, Lima, and Cyprimeria t exana •.••·.......•........••.••..•• 30 14. He.rd chalky limestone •••••·•••••••••• 40 Walnut formation: · 13. Gry!haea shell li$estone •••••••••••• 10 12. cha ky 1 i ~j_ est 0 n e ••..•.•..•••..•••.•. 1.66 ~ Taff,J.A.: "Report of the Cretaceous Ar3a North of the Colorado River," Third Ann. Rept., .lj.eol. Survey of Texas,1891,p.313. lO!rrll,R.T.: "The Geology of the :Black and Gr2.nd. Prai­ries", TJ. S. ~·Survey,Tv.:enty-fir::::t Ann. Rept. Pt. 7, 1900, p:-T88. 11. Hard limestone, with many small Gry!haea ....................... . 1.5 10. Cha KY limestone., with few Gry-. ffhaja •••••••••••••••••••••••••• 15.0 9. y limestone, containing Exoglra texana, GfY~haea pitcheri,and mmonite2, a! in great abun­dance •••••••••••••••••••••••••• 30.0 Paluxy Formation• In Johnson County the Walnut has a thick­ ness of one hundred feet. It is sandy at the base, but has twenty-five feet of shell conglom­ erate toward the top. Winton and Scott~lin their bullet in on Johnson County, give the log of the. Joshua well, which illustrates the character of the Walnut in this region. Log of the Walnut Formation in the Joshua well (Furnished by Mr. A. H. Woodfin) 40 ·feet shell • • • • • • • • • • • • • • • • • • • • • • • • • 490 Walnut 25 feet Pyrites and lLne •••••••••••••• 515 10 feet white sand •••••••••••••••••••• 525 10 feet blue shale •••••••••••••••••••• 535 10 feet white sand •••••••••••••••••••• 545 5 feet blue shale •••••••••••••••••••• 550 55 feet white sand •••••••••••••••••••• 605 Hill12gives a section described by Taff:3 which is much more detailed and accurate than the Winton,\'l.M. and Scott: "Geol. of Johnson County,"Univ. of Texas Bull.,No.2229,1922,p.61. 12-m:'Il,lr.T.: "Geo!:"' of the Black and Grand Prairies~ U.S. G13ol. Survey,Twent{-first Ann.Repl.,Pt.7,p.222. 13~f,J.1.: ntteport of he Cretaceous rea North of the Coloraa.o River, 11 Fourth .A.nn. Rept., Geol. S11rv~1 £..!.Texas, 1892, p.253. ­ 1 above section. The section is as follows: Section No.24--Section two miles south of Pl'easant Point, Johnson County, Texas (Taff) Goodland formation: Feet 8. Chalky white to buff limestone, vary­ing slightly in hardne0s, and bear­~ng numerous large Exogyra t exana, ~nallaster texanus, Lima wacoensis, Nat ica (?}, Turritelia'Seriatim­granulata, and Sphenodiscus peder­nalis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Walnut formation: 7. Vf-~ite to yellowish limestone, verymuch the sat11e in character as th8,t of No.8, but no fossils found •••••• 40 6. Thin-bedded, compact, yellow lime­stone, bearing many small Gryphaea marcoui •••••••••••••••••••••••••••• 10 5. Vihitish limestone, similiar to }Tos. ! and 8 •••••••••••••••••••••••••••• 15 4. Thin-bedded, hard, shaly limestone, bearing numerous small Gryphaea pit­cl1eri • . . . . • . . . . . • . • . . • • • • • • • • • . . • • • 2 3. Limestone, similar to No.5 ••••••••• 18 2. Basal Gryphaea limestone, the upper 10 feet composed almost entirely of fossil Gryphaea !itcheri, and con­taining many Sch oenbachia acuto­carinata; the portion below· this is a crumbling limestone, which bears many Gryphaea pitcheri and associated forms •••••••••••• ~ ••• ~ ••••••••••••• 30 1. Arenaceous lime marl which grades downwarct from the top with increas­ing proportion of sand to its con­tact with the Paluxy sand •••••••••• 15 Southward, in Bosque a.nd the surrounding coun­ ties, one find.s that the shell conglomerate at the top becomes gradually thinner and is displaced by thin layers of compact limestone containing a few small fossils, the shell conglomerate varying in thickness from a few inches to several feet, in­ terstratified with clay, and presenting this al­ ternating character from near the base through half of the formation. 14 In the valley of the north Bosque River Hill gives the following section: Section No. 20. Bosque River Valley Comanche Peak formation: Feet 6. Calcareous and argillaceous, chalky, white and light blue limestone, which contains in its upper portion Exo~yra tex­ana, in their greates develop­ ment in point of size, Enallaster texanus, Epiaster elegans, Ftolec­ tYJ?US ~lanatus, Sphenodiscu~ ~­ dernalis, Gr~phaea marcoui anO:­ casts of gas ropods •••••••••••• ~ ••• Vlalnut Clays: 5. Uppermost Grylhaea marcoui zone; compact thin ayers of limestone. The fossils are s:nall and are ee­mented in the hard limestone •••••• 3 4. Marly white to buff limestone bear­ ing but few fossils •••••••.••••••• 25 Fragments of oyster shells and fossils casts occur. On weath~r­ing, the marly lime breaks. up in­to soft marl and angular balls of marly lime. 3. Middle Griphaea marcoui zone; com­posed of ayers of hard and semi­crystalline lime, bearing numerous individuals of small Gryphaea ~­coui fossils ••••••••••••••••••••••• 3 2. Marly limestone beds •••••••••••••• ::;00 14 Hill, R.T.: "The Geology of the Blaalt and Grand Prairies, tt U.S. Geol. Survey, Tv,enty-first Ann. Rept.,pt.7,""""!900-;-p:-206. . The limestone layers composing this bed are of varying thick­nesses. Occasional hard bands project from the surface and leave fragments of limestone on the sloping hillsides. l. Soft marly and compact semi-cry­stalline limestone in alt·ernating lay­ers, varying in thickness from very thin bands to beds 3 to 4 feet thick•••• 35 Palnxy sand. Near the town of Clifton in Bosque county, a section was run from the top of the Glen Rose to the base of the Comanche Peak and the Walnut was found to have a thickness of one hundred and three feet. The following is a description of the sec­ tion: Section of Walnut, 4 miles east of Clifton, on Neils Creek. Feet 19. Compact limestone containing great numbers of small Gryphaea 2 18. Marly to chalky limestone con­taining very few fossils. Sec­tion for most part covered by vegetation ••••••••••••••••••••• 30 17. Ledge of semi-crystalline lime­stone, containing an abundance of Gryahaea. Fragments break off an are found on t he hillside.. 2 16. Chalky' to marly limestone, the exact character of which is hard to determine· because of the veget­ation. .Apparently the limestone is in ledges, for it varies in both density and thickness ••••••• 27 15. Semi~crystalline limestone con­taining few fossils ••••••••••••• 7 14. Soft marly to chalky limestone, alternating with clay and. con­tai~ing numerous Gryphaea ~­coui . .......................... . 8 13. Ciay alternating with Gryphaea shell breccia •••••••••••••••••• 5 12. Shell breccia containing Grypha­ea and Exogyra ••••••••••••••• ;·. .5 11. Arenaceous, yellow to white lime­stone, having Gryphaea, Exogyra and Pecten ••••••••••.••.••.•••• 3.0 10. Brecciated Gryphaea ledge •••••• .5 9. Arenaceous limestone with numer­ous Gryphaea ••••••••••••••••••• 2.0 8. Grfphaea shell breccia with uni­ va ves and bivalves •••••••••••• 5.0 7. Compact, dense, buff to white li~estone having stylolitic structure, with great numbers of Exogyra texana and. Gryphaea mar­ coui, as well 8.s a few Grano"C"&'F­ d!'ar-, Pecten, Turritella, and uni­valv·es present ••••••••••••••••• 4.0' 6. Argillaceou s li.11estone with Gry­ ~haea marcoui, Exo~yra texana, !valves and univa ves abundant 2 5. Arenaceous ana. argillaceous clay containing good specLr~ens of ~n­ §onoceras ·'. 4ea.ernalis •••••••:7.. 2 4. -hell breccia containing numerous fossils as, Gryphaea marcoui, Exo­ ~texana., .Protocs.rdia, Cyprr.:­ meria and many other 'Bivalves ••• 1.5 3. lrgillaceous and arenaceous clay with Gryphaea marcoui, Exogyra texana and .t!!ngonoceras pedernalis. 1.0 2. Shell breccia containing Gryphaea marcoui and Zxogyra texana••••••• 1. Compact arenaceous anQ argillace­ ous limestone, white to yellow in color ••••••••••••••••••••••••••• 1.0 Glen Rose Hill~5in his. Trinity River section, carries Hill,R.T.: "The Geel. of t!le Blac~c and Grand Prairies," U.S. Geol. Survey,Twenty-first Ann. Rept., pt. ~9mr:-p. 124. the Walnut through Terrell, Dallas, Ft. Worth, and Weatherford, slightly diagonal to dip. This section shows the greatest thickness yet described of the Walnut. The section is as follows: Section No.2--Ft.Worth or Trinity River Section Fredericlcsbnrg Division Goodland limestone, as seen in the West­Feet ern part of T2.rrant County: Crumbling chalky limestone, with character­ istic fossils ••••••••••••••••••••••••••••• 18 Alternate strnta of soft, massive white limestone and shelly limestone •••••••••••• 36 Walnut formation: -54 Alternations of soft and shelly li~estone and argillaceous li:ne :narl in str2.ta of 5 to 6 inches each •••••••••••••••••••••••• 14 Massive limestone ••••••••••••••••••••••••• 8 Alternations of compact and shaly li:nestone 68 Agglomerates of Gry~haea marcoui, with thin separation layers o~ marl ••••••••••••••••• 150 ---:i.30 Further southward, witn only a few local varia­ tions, the formation becomes increasingly argillaceous especially near the top, the contact with the overly­ ing formation being more easily discernable.. This 16 changing condition is well shown in Hill 1.s ' section on Bee Caves-Burnet road, at the western borrder of the Austin quadrangle. The following section was made at the summit of one of these buttes. I6" Ibid,:.p. 211. Section No. 21--Section at border of Blanco and Travis ~uadrangles, 4 miles south of the · Colorado River. Edwards limestone (upw~rd continuation eroded away): Feet 10. Firm white limestone containing flints 1 inch thick whic~ have been worked by the Indians. This is the lower portion of the Edwards limestone, which is here preserved as a cap rock less than 100 square feet in area...................... 1 Comanche Peak: 9. White chalky limestone •••••••••••• 15 .8. Firm oalcareo-siliceous clays con­ . taining great quant iti tes of Exo­~t eXana •• ~ •.•.•.•.••....:-:7'••• 10 Wal~u~ds: 7. · Thin, indurated layers •••••••••••• 0.25 6. calcareo-arenaceous clays contain­ing great quantities of Exogyra t exana •.•••.•••....•...••••..••••• 15 5. Yellow, rotten, honeycombed lime­stone ••.........................•.• 1 4. Yellow clay with abundance of Exogyra t exana .......•.•.•.••••....••.•••• 10 3. White chalky limestone band with Exo~ ~texana ............... ~ .....:-:-2 2. Firm limestone .••••••••••••.•.•••• 2 1. Yellow arenaceous limestone, form­ing ledge • . . . . . . . . . . . . . . . . • • • . . . • • 2 Glen Rose beds: Top of Glen Rose beds; firm, yellow arena­ceous limest one weathering into ledges. Total Comanche Peak beds in section ••••••• 25 Total Walnut beds in section •••••••••••••• 32 Total Glen Rose beds in section •••••••••••280 On the Burnett ro2.d, three and one-half miles west of :Bull Creek, the.re was found a good exposure of Walnut, having a total thickness of fifteen and a half feet. The section is as follows: 15 Bull Creek Section Feet Non-chalky, indurated lime • • • • • • • • • • • ~5 Yellow argillaoeous clay with an abun~ dance of Exogyra texana •••••••••••••• 6.0 Rotten honeycombed limestone, white to yellow in color, with Exogyra _texana and Engonoceras pedernalis ••••••••••• .5 Yellow calcareous clays with large num­ bers of Exogyra texana ••••••••••••••• 8.0 Ledge of arenaceous limestone ••••••••• .5 In the Walnut's southern extent, where it is closely associated with t '1e Glen Rose, it might easi­ly be mistaken for one of t·he clay members of the Glen Rose. The clay, however, of the underlying formation, although similar in color, contains neither the shell breccia nor the same fauna as the Glen Rose. This faunal change is discussed under the heading of Paleontology. The Walnut, too, is highly laminated on its weathered surface, tqe laminae appearing as shaly fragments. In the clay members of the Glen Rose, there is no such weathering. The Walnut thickens along its line of strike from Coolce southwa:r'd to Bosque and McLennan counties, where -. ' it attains its maximum thickness. From this regiofi, continuing along the strH:e, it thins to where 1t is only fi_fteen feet in Austin, but has a reported thick­ ' . ness of twenty feet in Medina County, where it dis­appears below later formations. This decrease in thickness southward is apparently accomplished by the disappearance of the lowe~ beds of the formation, the upper argillaceous layers being the predominant feature in this region. The sea approaching from the southwest, with alternate shallow and deep sea condi­tions, giving us limestone, clay and shell conglomer­ate attained its maximum depth in Bosque and the sur­roun~ing counties, and towards the latter part of the period sent an arm of the sea southward, giving us comparatively shallow water conditions as shown by the character of the deposits. The character of the material shows that the surrounding· land was low and featureless, for there is relatively little sand in the Walnut of Central Texas. In the~ depth of the sea, however, there are many .. local variations, showing warping of the bottom, and corresponding changes in the character of deposition as well as thickness. At Austin, there is fifteen feet of walnut, predominately clay; three. miles west of Fredericksburg there i's twenty feet of the forma­tion made up totally of clay; seventeen miles west of Fredericksburg one finds only nine feet of Wal­nut, with the lower seven feet made up of limestone, followed by two feet of clay, while seven miles west of Henly, in Hays county, one finds twenty-six feet of Vialnut, t he lower fourteen feet being compact lime­stone, followed by eleven feet of clay, which grades ·into a foot of poor grade limestone at the top. This well: illustrates the local variation in thickness and character of deposit over a comparatively small area of its outcrop. Paleontology Paleontologically, the Walnut shows a distinct faunal 4evelopment in comparison with the Glen Rose, \ \ ' both in n~mber and character of the fossils. At first sight the Walnut is noticeable by the great number of she·11s of E.xogyra texana f?._~_e_:n~!. and Gryphaea marcoui . Hill and Va1ighan, which are found in abundance in the clay as well as the shell breccia and limestone. It is this phase of the formation which caused it to be the first named and referred to as Exogyra texana beds and Tex~na beds. There is some development of Tylostoma~ , as shown by Tylostoma pedernalis J{o_emE}r ~~ and other species. There . rg also a great number of other smaller gastropods which will be described in the appropriate place. In the micro-fau na, the Orbitolina walnutensis Carsey is the best and mo st determinative horizon marker found.. It has a range which, a ::; far as is known, is limited strictly to the Valm1t formation. It is a fossil that is eazily identified, and is found in comparatively gro;;at abund2.nce in t'1e ·;,'alnut • .A comparison of the fanr.a of t h e 'Jalnut of Texas wi tb. tha-:; of I!:uropean :c~.nd ::exican formations, l .eads one to the conclusion the.t the \/alnut is middle Al­bian. There is :nuch more v1or~~ to be dor e, ~'10\·vever, in both :.i:urope and Am3rice. before an exact correla­tion can be made. T"he following description of the fauna of' the Walnut is not an exhaustive study, for ::1an,1,r rare and poorly preserved forms hav3 been omitted, but is here intended to be of practical value in determin­ing the formation as a uait, as well es a basis for separating the -.ialnut from the underlying Glen Rose. Cephalopod.s Engonoceras pedernal.is von Buch 1849: .Ammonites pec1ernalis Roemer: Texas, p.418. 1852: Ammon.:.tes ped.ernalis Roemer: Die Kreidebild.­ ,ungen von Texas, p.43,pl.l, fig . 3. 1869: Ammonites pedernuliG ~abb: ~eol. Surv. Cal., Paleont., Vol.2, Jp.258-259, pl.35,figs.l,la. 1901: Zngonoceras ;pederns.le Lassvvitz: Geol. Pal. Abh. (Koken) N•F., bd.6, heft 4. 1903: En.gonoceras pierd.enale Hyatt: U.:.>. Geol.Sur­vey, ~.fono. 54, p.165, pl.20, fig. 6-13. 1910: Engonoceras cfr. pedernale BBse: Inst. '.J.eol. Mex., Bol. 25, p.82, pl.11, fig . 1-3. Test medium, s nooth , involute, compressed; keel shar_p, narrow; concave nec.r the 1J_mbilicu.s, b1,_t becom­ing slightly convex out·;;ard..; st::.tures s.nall, numerous, . . . becoming srnaller and more numerous toward the umbili­cus; lobes are bifiCt ac.d. some apJ2 .. cently irregularly trifid; saddles are entire. Echinoid.s. Diplopodia texa.nnm Roemer 1849: Diadema t exanum Roe1:ier: Texas , p. 392. _1893: Diplopodia t exana Cragin: Fou.rt:>i Ann. Rept., Geol. Surv. Texas, p.149. 1893: Diplopodia texanum Clark: U.S. Geol. Sur­vey, Bull. 97, p. 48, pl.15, figs. 1 a-f; pl.16, figs. 1 a-d. Text snbcircul~.J' , larg e, with sides inflated; dorsal side g ently elevated; ventral side concave. Ambulacra conspicuous, with two rows of tubercles; poriferous zones narrowing towards ·the ventral side. · Interambulacra broad, Vii th two rows of tubercles increasing to fo1~r at tn.e ambitns. Peristome large, circular, wit~ distinct incisions; periproct sub-pentagonal, l arge. Znallaster texanus Roemer 1849: Toxast er texanus Roemer: Texas, p.393. 1852: Toxaste:r texanus Roemer: Die :creid.ebildung­ t:.ngen von TexG.s, pp.85,86, pLlO, fig.3. 1893: Enallaster inflatns Cr:-:>.~;in: Fourth J.nn. Rept., Geol. Surv. Texas, p.151. 1893: Enallaster t exanus Cla:r.k: 0. 3. Geol. Su r­vey, Eull.97, p. 78 , pl.39, figs. 2 a-g. 1910: Enallast er texanu.s Bose: Inst. Geol. Mex., Bel. 25, p.166, pl.40, fLgs. 6-10; pl.41, figs. 2-4; pl.42, fig. 1. 1915: Enallaster texanus Clar:!.: and. Twitchell: U. s. Geel. Survey, 1~!ono. 54, p. 86, pl.39, figs. 2 a-g. 1919: £nallast er texarrus Ad.kins and. Winton: · Univ. of Texas Em.il. Ho. 1945, p. 55~ :pl.9, figs. 12,13. Test mediuta, elongate, cord.iform; dorsal side elevated., convex; ventr2i side flat, concave at the peristome; anterior portion broad, rounded, .with deep anterior groove; i:iosterior j_)Ortion trt1n­cate; side inflated; rounded. T~e ambnlacra are n~eq_ual, and. na rrow; antero-la teral pe,ir la.ege, curving bacl\:wa.rd. as the~r progress outward; po~tero­lateral pair symmetrical and short. The pores are unequal, the posterior ones are elongate, the outer nearly t~ice as large as the inner series; pores of anterior zone small and regular. In the anterior It. groove there o.re unpaired ambulacrum-, the area be­ing twice as wide as t he ot1:1Br areas. The apical system is compact. Holectypus ;planatus Roemer 1849: Holectypus planG.tus Roet:1er: Texa s, p.393. 1852: Holectypus ;planatus Roemer: Die Kreide­ bildungen von Texas, p.84,pl.10, figs. 2 a-g. 1853: Holectypus plan;::.tus Shurn.P.rd: Pal. Zxpl. Red River of La., p. 211. 1857: Holectypus planatus Conrad: Mex. 3clry. Surv. Vo 1. I, p. 145, pl.1, fig. 4 a-f1• . 1858: Holectypus glanatus Descir: Synop. Zchin­ oides Foss., p. 174. 1892: Holectypus planatus Cragin: Fourth Ann. Rept., Geol. Surv. Texas, p. 159. 1893: Hole.ctypus pla.natn s Clark: u.s. Geol. Survey, Bull. 97, .P. 58, pl.23, figs. 2 a-f. 1915: Holectypus planatus Clarli:: and Twitchell: U. S. Geol. Survey, Mono. 54, p. 65, pl.25, figs. 2 a-f; pl. 26, fjgg.;~: . 1 a-e. 1916: Holectypus planatua '1111.itney: Bull. Am. Pal., No. 26, p. 12, pl. 7; figs~l-5. 1919: Holectypus planatus Adkins and Yiinton: Univ. of Texas Eull. lirq. 1945, p. 50, pl. 9, fig.2. Subcircular to pentagonal, symmetrical; dorsal side convex; ventral side flat to concave on approach­ing peristome; ap.ical system small; ovarial plafes perforated, with :nadreporite l arge but difficult to distinguish; ambulacra are straight, narrow, with increase in wid.th toward a mbi tus; poriferous zones narrow, with pores increasing in size towexd the ambitus; interambulacra about three times tb.e width of the ambulacra; plates narrow, each having a row of small tubercles, five or six at the ambitus, but fe~ above and below. Holectypus planatus distinguished. fro~ H. limitis by th~ shape of periproct. In H. planatus periproct is located nes.r t:-~e tnarg in of the test and has both ends pointed, ',,!J.ile t~1e :peri:proct of H. limitis is smaller and. h2.s only t :1e end. approsch­ing the marg in pointed. Pseudod.iadema. texanum Roemer 1849: ::Viadema texanum Roemer: Texas, pp .392,393. 1852: Diad.ema tex2.num Roee1er: Die Kreidebild.ung­ en von Texas, p. 82, :pl. 10, fig. 5. 1858: Pseud.odiadeina texanum Desor: Synop. Echin­ oid.es Foss., p. 72. 1893: Pseudodiadema tex:::.num Cragin: Fourth Ann. Re:pt. Geol. Surv. Texas, pp. 161, 162. 1893: Pseudodiadema texanum Clark: U.S. Geol. Survey Bull. 97, .P.P• 47,48, pl.13, figs.2 a-n; pl.14, figs. 1 a-g. 1915: Pseudodiadema texanum r;lar~{: a11d. Twitchell: U. s. Geol. Survey, I:rono. 54, p. 55, pl.18, figs. 1 a-i. Test small, circular, wit~1 sides inflated.; dor­sal and. ventral sides equally depressed; ambulacra narrow, with two rows of pro::ninent tubercles, de­creasing in size from t:1e ambi tus to t he poles; poriferous zones narrow, wit':l minute granules inter­spersed; interambulacra zone wide, with two rows of tubercles of, greater size than those of the a!i'.l.­bnlacra; peristome large, covering h2.lf of test; _periproct si.ibcircular, v1ith deep incision in right anterior ambulacrum. Pelecy_pod.s Anatina whitneyi n.sp. Pl~ I, figs. 1-2. Shell medium, elo.og:::.te-ovate, in.equilateral; posterior end greatly produced.; umbos low, depressed, located approximately at the anterior margin; ventral , margin slightly curved, with well rounded curves at anterior ana. posterior margins. The ornamentation consists of concentric undulations parallel with the lines of growth. Cucnllaea terminalis Conrad 1857: Cucullaea terininalis Conrad.: :Mex. Bdry. Surv., p. 148, pl.4, figs. 2 a,b. 1892: Cucullaea terminalis Cragin: Fourth .Ann. Rept. Geol. Surv. Texas, .P• 174. 1893: Cucullaea terminalis Hill: Proc. Biol. Soc. 25 of Washington, .P• 26. Shell cuneiform, triangular, ventricose; beak;s promine!'..t, adjacent to anterior extremity; bending forw8.rd and inward, apecis little com­pressed.;posterior end produced., ant;ular; ventral margin straight, extensive; both muscle impressions strong. Cyprimeria texana Roemer 1852: ArcoRa.gia texapa Roemer: · Die Kreid.ebild­ ungen von Texas, pp.46, 47, pl.6, figs.8 a,b• . 1857: Arcopagia texana C·onrad: Mex. Bdry.Surv., p. 149, pl.4, figs. 3 a,b. 1893: CYI>rimeria texana Cragin: Fourth .Ann. Rept., Geel. Surv. Texas, .P• 177. 1919: Cyprimeria tex-ana Adkins and Winton: Univ. of -·~;.;, Texas Bull. :No. 1945, p. 76, pl.18, 'fig. 6. Cast is subcircular, thin, inequivalve; right valve gently convex, with t :ie left valve only slight­ly so; beaks somew!lat raised, and. cent rally loc 2.ted. · surface markings rare, but sometimes shows hinge structure and. muscle scars. Cyrena brilli n. sp. Pl.II, figs. 1-2.. Shell medium to small, convex, subtrigonal,' equi­ lateral; anterior and po sterior extreinities ger1t­ly rounded; beaks rather prominent, depressed. an­teriorly, practically central; dorsal outline de­clining unequally from the beaks in front and rear, the anterior slope being concave in outline and the' posterior convex; ventral margin forming an elliptic curve; surface marked. by very fine growth lines. Exogzra texana Roemer Pl. III, fig. 1. 1849: Exogyra texana Roe::ier: . Texas, pp. 396,397. 1852: Exogyra texana Roe~;ier: Die Xreid.ebiidungeli · von Texas, p. 69, pl.10, figs. 1 a-e. 1853: ilogyra texana Shumard: Expl. Red River, La., p. 205, pl. 5, figs. 1 a,b and. fig. 5. 1855: E.xogyra texana Blal:e: Rep. Expl. and. $ur. P.R.R. Mississippi River to Pacific Ocean, Vol~ 2, .P• 39. 1884: Exogyra texana White: Fourth Ann. Rept. U. S. Geol. Survey, p. 306, pl. 51, figs. 1-5. 1899: Exogyra texana Hill: u.s. Geol. Survey, Twenty-first Ann. Rept., pt. 7, pl.27, figs. 1 a, b. 1910: ZXogyra texana B6se: Inst. · Q.eol. l:Iex., Bol. 25, p.112, pl.20, figs. 14-16; pl.21, figs. 1-11; pl.22, figs. 1-9. 1919: Exogyra t exa.na Adki ns a nd. ·;:inton : Univ. of Texas Bull. t:o . 1945, .P• 64, pl.13, fig s. 15-16 . Shell su b-oval, curved; dorsal valve convex, provided, v;it ::-i blunt keel; outer su rface cover ed. with irregu.la r, raG.iat ing ribs, slightly lamina tea.. by growth marks; ventr2.l valve covered with s::i.all ra diatine; ribs, at times indistinct; valve convex with slightly sloping surfaces, cor responding to dorsal valve; attachment area of beaks distinct and large on int erior of sh ell; interior of both valves smooth, with border finel y s triated. 3-ryghaea marcoui Hill and 'Vaugha n 1898: Gryphaea marcoui Hill and Vanghan; U.S. Geol. Survey, Bull. 151, _p. 50, ~ls. 2-5. 1919: Gryphaea marcoui Adkins and l/inton: Univ. of Texas Bull. No. 1945, .P• 61, pl .15, figs. 15~18. Sub-oval-to oval; bea.i.c narrow, slig~1tly trun­cated, overlapping t he h i nge line; surfa ce rough, with dorsal sinus runni ng entire length of sh ell, a.a.a. flaring 2.t its ventr::i,l mB.rgin; flaring of wing not extensive as compared wi t :1 other fo r ms of Gryph.a.ea, and givi.ng' shell a na rrow appearance. Granocardium al.leni n. sp~ Pl. IV, figs. 1-2. Shell medium, co rd.G.te, slightly inequilater­al; globose dorsally, sloping gently ventrally; umbose conspicuous, incurved, produced, located ap­proximately central in relation to hinge line; hinge line gently curved. Surface ornamentation consists of radiating grooves and. ribs, from which arise coarse spines and granules. Homomya Cuyleri n. sp. Pl. V, figs. 1-2. Shell medium, globose, elongate, e~uivalved, inequilateral; posterior end. distinctly prod..uced; umbo~ low' curving downward., ana. situated ap_proxi­mately at anterior margin; dorsal margin straight; ventral margin not whole in specimen; ornamenta­tion. consists of concentric growth lines of vary­ing intensity. l::odiola concentrico-costslla,ta Roemer 1849: M:odiola concentrico-costellata Roemer: Texas, l?• 403. 1852: 11odiola concentrico-costellata Roemer: Die ~tdebildungen von Texas, p. 54, pl.7, fig. 10 a, b, c. Test moderate, trapezoid, gently arched; pos­terior portion narrow, >Vi th middle and anterior por­ tio·n inflated, _broadest nea r the middle; beaks small and only slightly elevated above the hinge line, and in approximate contact ; proceeding from beaks are narrow longitudinal ridges, broadly rounded, to the posterior part of t 11e basal marg in, belovv which, in the mi.J.dle, t he flanks are concave; surface marked by concentric growth lines. n-eithea irresularis B6.r 1910: Vola irregularis Base: Inst. Geol. de Mexico, Bo1. 25, pp .97 ,98, pl.15, figs. 10-18. 1918: N_eithea irregular is Kniker: _ Univ. of Texas Bull., 1817, pp. 18,l9, pl.2, figs. 1-6• . 1919: Pecten irregularis .Adkins and 'iiinton: Univ. of Texas BUll. no. 1945, p.67, pl~ 11, figs. 11-15. Shell slender, elongate, subtrigonal, eqnilateral; hinge line stro.ight, with nmbos i ncurved; right valve sub-oval, rouDded, convex; surface ornament ea. with high, narrow, radiating ribs, averag_ing sixteen in number; every t h ird rib raised slightly above the other, and much wider than those in the depr essions. The furrows between the ribs are narrow, conc2.ve, but much wider ad.joining tli:e rai~ed ribs. ·Fine ter­tiary ribs can be seen on t h e side of the prominent, . . . raised ribs, in specimens not too badly weathered. The radiating ribs . of the l eft valve correspond. with the fnrror;s of t'1.e right valve. Protocardia texana Conrad 1857: Cardinm (Protocardium) texana Conrad: Mex. Bdry. Surv., p. 150, pl.4, fig. 6, a-c. 1919: Proto card.iu texana .E..d.kins and. ':iinton: Univ. of Texas Bull. Ho. 1945, .P• 75, pl.18, fig. ·Test medium, snbcircular, inflated, cord2.te; p-os terior end. rounded; umbos pro :~is((!) parryi Conrad~8 A comparison of this vii th Conrad• s19origin­al will clearly show the difference in genera. Tylostoma peder.aalis Roemer 1849: Natica pedernalis Roemer: Texas, .P• 410. nr.­ . · Proc. of the Geol. Soc. of ;·1ash., 1893, pl.6,fig.l.19-:------­ Mex. Bdry. Surv., 1857, pl.13, fig.5, a,b. 1852: Natica pedernalis Roemer: Die Kr..eide­ bildungen von Texas, p.43, pl.4, figs. 1, a, b. 1893: Tylostoma ped.ernalis IIill: Proc. of the Biol. Soc. of ·1/ash., p.33, pl.6, fi,g.2. Test ovate, large; whorls are gently rounded. to flat, angular above; basal whorl largest and. most prominent; spire short, s·Eb-truncate, consisting of three whorls; aperture elliptical, ovate. Corals Parasmill.a sp. Test small, conical, and approximately straight. The septa are plainly visible, ~·lith a series of secon­daries and tertiaries, giving the appearance of com­pP.ctness. Family lituolidae Orbitolina walm1tensis Carsey 1926: Orbitolina walnutensis Carsey: Univ. of Texas Bull. No. 2612, p.23,pl.7,figs. 11 a,b~ Test is medium, conical, and generally smooth; base of shel_l gently concave; slightly higher t":lan broad; chamb.ers porous and numerous. Undetermined Phylum Porocystis globularis Giebel 1853: Siphonula globularis Giebel: Beitr. derPal., .. ~--; .... Bohn. 189'3 . : "P t . _orocys is, Gen. nov. r! ..,.1ragin: Fourth Ann. Rept., Geol. Surv. Texas, p. 165. 1893: Porocystis pruniformis Cragin: Fourth Ann. Rept., Qeol. Surv. Texas, p.165, pl.24, figs. 2-6. 1893: Araucarite ward.i Hill: ~-iash. Biol. Soc. Proc • . Vol. 8, p.39, pl.l, figs. 1 a,b,c, a.. 1895: Porocystis pru:lifor:·t1is Ra.uff: Heues Jahr­ buch ~Un., Band I, Seite I, Tofel I·;il"+, holzschmitt. 1895: Araucarites warcli Hill: Neues Jahrbuch Min., Bancl I, Seite I, Tofel 1-15, holzschmitt. 1905: Porocystis pruniforr!lis Jarvis: Biol. Bull., Vol.9, p.388, figs.1-6. Cyst globular, spheroid~l; aperture marginal to slightly inverted.; surface ro11 gh, pitted, granu­lated; interior structureless. kll specimens poorly preser•;ecl. BIBLIOGRAPHY Adkins, w.s.: llGeology and Mineral Resources of McLennan County, 1' Univ. of Texa s Bull.!ro. 2340, 1923. Ad.kins, w.s. and Hinton, ~'I .E.: rTPaleontologica l · Correlation of the Fredericksburg and Washi­ta Yor:nations in Horth Texas, 11 Univ~ of Texas~· No . 1945, 1919. Bak~r, C.L. : 1'Ex.:plorato r.)' Ge .Jlogy of a. Part of Southwestern Trans-Pecos ~exas,lf Univ. of T.exas ~· Iro. 2745, 1927. - Beede, J.'ii . and Waite, v.v.: 1'The Geology of Runnels County, :i :Jniv. of Texas Bull. I:ro. 1816, 1918. ~---~ B8se, Emil: rruronogra:phia Geologica y Palentologica del Cerro de !·.~uleros, ff. Bol. del Inst. Geol. · de Uex., No.25, 1910_. --­ Boyle, C. B.: . 11li.. Catalogi1e and :Bibliography of North American liesozoic InYertebrates," u. 3 .• Geol. Survey ~· 102, 1893. · -~ Car$ey, D.O.: 11Foraminifera of t he Cretaceous of · Central Texas, rr ~· of Texas ~· I·::o.2612, 1926. Clark, Vl . B.: rrThe l:Iesozoic Echinodermata of the United States,n U.S. '}eol. Survey Bull. 102, 1893. Clark, \::.:s., and Twitchell,I~.T.: !'The :Mesozoic 8.nd Cenozoic Echinoc1ermsta of the United Stat es, 1' U.S. ".}eol. Survey, Hono. 54, 1916. Conrad, T.A.: irReport 0f t'-1·8 Unit ec1 ihat es and Mexican Bonn'12.r{'"S\)_ryey, Vol.I. part 2,1857. Cragin,F.w.: rrA Contribution to the Invertebrate Paleontology of t he Tex8.s Cretaceous, rr Geol. 3urv. of Texas , F01;rth Ann. Rept., p:y.l~246, l'S"9'3'.---- Dumble, E.T.: nThe Geology of East Texas, 11 Univ. of Texas Eull. No . 1869, 1918. 36 Ellisor, A.c.: "Specie s of Turritella from the Bud.a and Georgetown Lima;.::tone of Texc..s, 11 ~.__.£! Texas Bull. ::o. 1840, lSlS. Hill,R.T.: 11 The '.J.eology of the r.lacl::. and Grand Prairies, n U.S. ·8-eol. Survey TvJenty-first Ann. Rj~t~,--p-t.7~JO. . 1TPre 1minary Annotated. Chee:: List of the Cretaceous Invertebrate Fossils o~ Texa~," Geol. surv. of Texas, Bull. No.4,-1889. Ta:Ieontoro~iof the Cretaceous Formations of Texas, Aus in-;-lmr9".__ . HTfie Invertebrate Paleontology of t he Trinity Division, lf Proc. Biol. Soc. of Viashington, Vol. 8, 189-Z:--. ­ Hill,R.T. and '!faughan., T.W.: '1The Lm-.er Cretaceous Gryphaea of the Texas Region~' :lJ. S. Geol. Survey Bull. 151, 1898. -~ -:;---­ Hyatt, A.: 11Pseuclocer~'-tites of the Cretaceous, rr U.S. Geol. Surve~r , Mono.44, .1900. · Kniker, H. T.: ·11 Comanchean and ':"retaoeous Pecti.tii­ dae of Texas, 11 ~· of Texas Bull, No.1817, 1918. Liddle, R.A~: nThe Geology and W:.inero.l Resources of !·Jedina C'ounty, 11 Univ. of Texas Bull. No. -1860, 1918. --­ Paige, Paul: 11Llano-Burnett Folio, 11 Geologic. Atlas of ~United States, Eo . 183, 1912. Roemer, F.: Texas, Bonn, 1849. ----Die Kreid.ebildungen von •rexas ~~Organischen, Einsoh!usse, Bonn, l~. Shattuck, G~B. : · trThe !,Tollusca of the Bttda Li~nestone, 11 U~S· Geol. Surv. Eull. 205, 1903. Shumard, B.F.: 11 Description. of Speci ';S of Carbonifer­ous and Cretaceous Fossils,rr i n 11Ezploration of the Red River of Louisiana, 11 Repts. on Hat. 'Hist. washington, 1853. ' --- SLnonds, F. v'i.: 11Eibliogra_phy of Texas IJ.eology for the Decade 1890-1900 , ir Trans. Te,xas Acad.. of ~·, Vol.III. Taff,J.A.: 11Reports of t 11e C:retaceous Area North of the ~olorad.o River, 11 Geol. 3urv. of Texas, mi • d. ' t 1891 ~~ ~ ~tlir ~nn. R~g ., . ttReporrs0f ne Cretaceous AreG. Nort}1 of the ~olorad.o Riv8r~ '.}eol. Surv. of Texas, Fourth Ann •. Rept., 1892-.-.----­ Udd.en, J.A.; Bak~r,~.L., and BHse, 3.: "Review of the '.}eology of Texas, 11 Univ. of Texas :Bull. No.44, third. edition., lm7 · \'lhi tney, F. L.: :rThe Zchinoide2. of the Bud..:.. Lime­stone, rr Bull. Amer. Pal. Ho.26, 1916. ----nThe Fauna of the Bud.a. Li:nestone, n Univ. of Texas Eull. IJo. 184, 1911. ----Biblio~~y and. Index of the l~orth America Mesozoic aunas-(ManuscrTp~opy). Winton, ~.M.: "The Geology of Denton County, 11 Univ. of Texas Bull. Ko. 2544, 1925. Winton, V.M. and Ad.kins, ~.s.: nThe Geology of ' Tarr2.nt County,H Univ•. of T.e:xas :Bull. ~To. 1931, 1919. Winton, W .M. and Scott, G.: 1'The Geology of Johnson County, :r Univ. of Texas Bull. No. 2229, 1922. PLATES --.... ---­ PLA.TE I PLAT~ I Figures l-2. . A.natina whitneyi n. sp. T ..l. PLA'l:..:: II PLATE II Figures 1-2. Cyrena brilli, n. SJ;l. 1 rLA.:.c; III Figure 1. E.xogyra texan.a .Roemer --, -.J.J -~..i...J...J .L..L 1. PLA'l'.i:! IV PLATE IV Figures 1-2. Granocardium alleni n. sp. PLATE V PLATE V Figu.res 1-2. Homomya ouyleri n. sp. -..1.J. ' PLAT3 VI PLATZ VI Figures 1-2. Protocard.ia walnutensis n.sp. 1. (:.; .