14.GS: tlPI 77 c. 1 STATE OF ILLINOIS DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION FRANK G. THOMPSON, Director DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief URBANA REPORT OF INVESTIGATIONS — No. 77 CHESTER OSTRACODES OF ILLINOIS BY CHALMER L. COOPER PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1941 CIBRARY STATE OF ILLINOIS SPRINGFIELD, ILLINOIS STATE OF ILLINOIS DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION FRANK G. THOMPSON, Director DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief URBANA REPORT OF INVESTIGATIONS — No. 77 CHESTER OSTRACODES OF ILLINOIS BY CHALMER L. COOPER PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1941 STATE OF ILLINOIS HON. DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. FRANK G. THOMPSON, Director BOARD OF NATURAL RESOURCES AND CONSERVATION HON. FRANK G. THOMPSON, Chairman EDSON S. BASTIN, Ph.D., Geology WILLIAM A. NOYES, Ph.D., LL.D., Chem.D., D.Sc, Chemistry ^ LOUIS R. HOWSON, C.E., Engineering WILLIAM TRELEASE, D.Sc, LL.D., Biology EZRA JACOB KRAUS, Ph.D., D.Sc, Forestry ARTHUR CUTTS WILLARD, D.Engr., LL.D. President of the University of Illinois STATE GEOLOGICAL SURVEY DIVISION Urbana M. M. LEIGHTON, Ph.D.. Chief ENID TOWNLEY, M.S., Assistant to the Chief JANE TITCOMB. M.A., Geological Assistant GEOLOGICAL RESOURCES Coal G. H. CADY, Ph.D., Senior Geologist and Head L. C. McCABE, Ph.D., Geologist (on leave) R. J. HELFINSTINE, M.S., Assoc Mech. Eng. JAMES M. SCHOPF, Ph.D., Asst. Geologist J. NORMAN PAYNE, Ph:D., Asst. Geologist CHARLES C. BOLEY, M.S., Asst. Mining Eng. BRYAN PARKS, M.S., Asst. Geologist Industrial Minerals T. E. LAMAR, B.S., Geologist and Head H. B. WILLMAN, Ph.D., Assoc Geologist DOUGLAS F. STEVENS, M.E., Research Associate ROBERT M. GROGAN. Ph.D., Asst. Geologist ROBERT R. REYNOLDS, B.S., Research Assistant Oil and Gas A. H. BELL, Ph.D., Geologist and Head G. V. COHEE, Ph.D., Asst. Geologist FREDERICK SQUIRES, B.S., Assoc Petr. Eng. CHARLES W. CARTER, Ph.D., Asst. Geologist WILLIAM H. EASTON, Ph.D., Asst. Geologist PAUL G. LUCKHARDT, M.S., Research Assistant WAYNE F. MEENTS, Research Assistant Areal and Engineering Geology GEORGE E. EKBLAW, Ph.D., Geologist and Head RICHARD F. FISHER, M.S., Asst. Geologist Subsurface Geology L. E. WORKMAN, M.S., Geologist and Head TRACY GILLETTE, Ph.D., Asst. Geologist ARNOLD C. MASON, B.S., Asst. Geologist KENNETH O. EMERY, Ph.D., Asst. Geologist MERLYN B. BUHLE, M.S., Asst. Geologist FRANK E. TIPPIE. B.S., Asst. Geologist Stratigraphy and Paleontology J. MARVIN WELLER, Ph.D., Geologist and Head CHALMER L. COOPER, M.S., Assoc Geologist Petrography RALPH GRIM, Ph.D., Petrographer RICHARDS A. ROWLAND, Ph.D., Asst. Petrographer Physics R. J. PIERSOL, Ph.D., Physicist B. J. GREENWOOD, B.S.. Mech. Engineer DONALD O. HOLLAND, M.S., Asst. Physicist PAUL F. ELARDE, B.S., Asst. Physicist DONALD W. HANEY. B.S., Research Assistant GEOCHEMISTRY FRANK H. REED, Ph.D., Chief Chemist ROBERTA M. LANGENSTEIN, B.S.. Chemical Assistant Coal G. R. YOHE, Ph.D., Assoc. Chemist MYRON H. WILT, B.S., Research Assistant Industrial Minerals J. S. MACHIN, Ph.D., Chemist and Head DELBERT L. HANNA, B.A., Research Assistant Fluorspar G. C. FINGER, Ph.D., Assoc. Chemist EVERETT W. MAYNERT, B.S., Research Assistant X-ray and Spectrography W. F. BRADLEY, Ph.D., Assoc Chemist Analytical O. W. REES. Ph.D.. Chemist and Head L. D. McVICKER, B.S., Asst. Chemist P. W, HENLINE, M.S., Asst. Chemical Engineer WILLIAM F. WAGNER, M.S., Asst. Chemist K. F. BURSACK, B.A., Research Assistant MARION LUND DICKMAN, B.S., Research Assistant MINERAL ECONOMICS W. H. VOSKUIL, Ph.D., Mineral Economist GRACE N. OLIVER. A.B., Assistant in Mineral Economics EDUCATIONAL EXTENSION DON L. CARROLL, B.S., Assoc Geologist PUBLICATIONS AND RECORDS GEORGE E. EKBLAW, Ph.D., Geologic Editor CHALMER, L. COOPER, M.S., Geologic Editor DOROTHY E. ROSE, B.S., Technical Editor KATHRYN K. DEDMAN, M.A., Asst. Technical Editor ALMA R. SWEENY, A.B., Technical Files Clerk PORTIA ALLYN SMITH, Asst. Technical Files Clerk RUTH E. ROTH, B.S., Asst. Technical Files Clerk MEREDITH M. CALKINS. Geologic Draftsman LESLIE D. VAUGHAN, Asst. Photographer DOLORES THOMAS SIMS, B.A., Geologic Clerk Consultants: Ceramics, CULLEN W. PARMELEE, M.S, D.Sc, and RALPH K. HURSH, B.S., University of Illinois: Pleistocene Invertebrate Paleontology, FRANK COLLINS BAKER, B.S. Mechanical Engineering, SEICHI KONZO, M.S., University of Illinois, University of Illinois; Topographic Mapping in Cooperation with the United States Geological Survey. This Report is a Contribution of the Division of Stratigraphy and Paleontology. October 1, 1941 CONTENTS PAGE Introduction 5 Range of Chester ostracodes 5 Chester stratigraphy 5 Distribution 7 New Design group 7 Renault formation 7 Paint Creek formation 8 Romberg group 9 Golconda formation 9 Glen Dean formation 10 Elvira group 10 Vienna formation 10 Menard formation 10 Clore formation 11 KInkaid formation 11 Chester correlations 12 Amsden formation 12 Reynolds formation 12 Fayetteville shale ' 13 Faunal chart 14-21 Collecting localities .22 Systematic description 23 Acronotellldae 23 Bairdiidae . 24 Beyrlchiidae 35 Cytherellidae 35 Drepanellidae 39 Glyptopleuridae ' . 40 Graphiadactyllldae 45 Holllnellidae 45 Kirkbyldae 46 Kloedenellldae 54 Leperditellidae 61 Primitiidae 63 Youngiellidae 64 References 65 Index 97 Digitized by tine Internet Arciiive in 2012 witii funding from University of Illinois Urbana-Champaign http://archive.org/details/chesterostracode77coop CHESTER OSTRACODES OF ILLINOIS BY Chalmer L. Cooper INTRODUCTION The first descriptions of ostracodes apparently of Chester age were pub- lished during the last half of the nineteenth century by some of the early workers in Great Britain and were based on specimens collected from the Carboniferous "Lime- stone Series" of England^ The first Ameri- can species were described by Ulrich in 1890 from beds in Kentucky and Illinois, but these fossils seem to have aroused little interest among paleontologists until after the first quarter of this century. The study of well cuttings by geologists connected with the petroleum industry and the recognition of the value of micro-fossils as horizon markers has resulted in a revival of interest in Carboniferous ostracodes, and since 1927 the number of published studies has steadily increased. The discovery of oil in the Ches- ter series of the Illinois basin has recently directed attention to these ostracodes, and several papers have been published by Cro- neis, Coryell, their students, and others. During this time several studies on other Chester formations appeared, chief among which were those of Coryell and Sohn (1938) on the Reynolds (Mauch Chunk) of West Virginia, Morey (1935) on the Amsden of Wyoming, Harlton (1929) on the Fayetteville of Oklahoma and Arkansas, and Roundy (1926) on the Barnett and Chappel of Texas. The Fayetteville fauna described by Girty (1910) should also be mentioned although it was not illustrated, since two important Carboniferous ostra- code genera were first described therein, one of which, Amphissites, was subsequently figured by Roundy. iFor a complete bibliography of Chester ostracodes up to 1934 see Bassler, R. S., and Kellett, Betty, Biblio- graphic Index of Paleozoic Ostracoda: Geol. Soc. Am., Spec. Paper 1, 1934. Subsequent references will be found in the various synonomies and in the list of references at the end of this report. The present study was undertaken to de- termine the stratigraphic ranges of all Ches- ter ostracode species known in Illinois. It is based principally upon new collections obtained from outcrops, but is supplemented by samples from the cores and cuttings from a few wells. Many of the faunas are sur- prisingly rich, and fully one-third of the species recognized here are new. Although it is the first complete record of the distri- bution of Chester species, in so far as they are now known, this study must be regarded as a report of progress, because many more new species will probably be recognized upon the study of additional collections. The accompanying faunal chart lists 359 species of Chester ostracodes, only 35 of which are not known to occur in Illinois. The determined stratigraphic ranges of spe- cies described from other areas, but also occurring in Illinois, permits the more pre- cise correlation of widely separated Chester formations with the standard section than was formerly possible. Few species are identified with European forms, and these with some hesitation and only after careful study. RANGE OF CHESTER OSTRACODES Chester Stratigraphy The Chester series^ in the Illinois basin, cropping out in southern Illinois and adja- cent parts of Indiana and Kentucky, con- sists of eight limestone and shale formations alternating with a like number of sandstone or sandy shale formations. The limestone and shale formations vary considerably in both lithology and thickness. The sand- stones are largely nonmarine although some 2 For a recent, more complete discussion of the details of Chester formations see Weller and Sutton (1940, pp. 819-853), and Weller (1940, pp. 31-35). 5] CHESTER OSTRACODES OF ILLINOIS contain marine fossils at a few localities. The}' also are quite variable in character and usually can be identified only by their association with the adjacent limestone- shale formations. With the exception of the Aux Vases, all New Design and Romberg formations thin to the west, the Bethel being represented by a cherty horizon in outcrops near Missis- sippi River. There the Renault and Paint Creek are clastic littoral deposits, but con- tain considerable limestone to the east be- yond the limits of the Aux Vases. Neither the Cypress nor the Hardinsburg is well developed in the west, the latter being pres- ent as a cherty zone in the Okaw formation. The upper Chester, the Elvira group, seems in general more uniform than the lower groups, although the Vienna, Wal- tersburg, and Palestine thin both east and west from a central area in Johnson and Pope counties. The Degonia thins to the east, seemingly to compensate for the thickening of the Clore in this direction. The be- havior of the Kinkaid is not very well known, as its thickness is quite variable due to pre-Pennsylvanian erosion. The other formations of the Elvira thin to the west. Many of the Chester sands thin and dis- appear, and the limestone-shale formations thin and become more dominantly shale to the southeast in west-central Kentucky, where the entire Elvira grades into a single shale unit, the Leitchfield formation. To the north in Indiana, however, the Chester sandstones are all present, though thinner and more shaly than in the central part of the basin. Ostracodes are abundant in some calca- reous shale beds of all of the Chester lime- stone-shale formations. The number of spe- cies recognized in each formation is roughly proportional to the number of collections studied. Although the greatest number of species, 94, is recorded from the Golconda (7 collections) and the smallest number, 40, from the Glen Dean (2 collections), it is believed that continued study will maintain about the same proportion of species shown in the check list on page 8. Like the larger invertebrate fossils a greater number of diagnostic species occur in the lower than in the higher formations. In the New Design group 50 per cent of the species are, so far as now known, restricted to one formation, whereas in the Romberg and Elvira groups only 39 and 30 per cent respectively are so restricted. The greatest change in ostracode faunas appears to occur at the Homberg-Elvira boundary. Only seven species are known to be present in both the Glen Dean and Vienna formations, although 21 of the 40 Glen Dean species occur in the Golconda, and of the 48 Vienna species 32 occur in the Menard. This relationship may be some- what exaggerated because of the relatively small number of Glen Dean and Vienna species that have been recognized, but it seems unlikely that additional material would entirely eliminate this discrepancy. In contrast the New Design - Homberg boundary is not so clearly marked by change in the ostracode faunas. Eighteen species are common to the Paint Creek and Gol- conda, whereas 15 of the 61 Paint Creek species occur in the Renault and 20 of the 94 Golconda species are represented in the Glen Dean. The following table shows sim- ilar relationships for all of the Chester formations. Sixty-seven genera of ostracodes have been recognized in this study. Of this number 27 are, as far as known, restricted to the Mississippian system, 11 range from the Devonian to the Pennsylvanian, seven oc- cur in both the Devonian and Mississippian, and 22 are present in both the Mississip- pian and Pennsylvanian. Genera alone are of little or no stratigraphic significance. Only eight genera are known from but a single formation and all of these are rare forms, five of them being known from only one species each. Additional collections will undoubtedly extend most of their ranges. Over half of the known Chester species, however, appear to be restricted to a single formation. This does not mean, however, that these are all good index fossils. The distinguishing characteristics of the species in several genera are so slightly different that, even though usually found in great abundance, they are easily confused and therefore are of little value for correlation. Falling within this category are Bairdia, CavelUna, Healdia, and a number of the species of the old Amphissitinae, many of which are included in the new genera Ecto- de?nites and Polytylites. RANGE OF CHESTER OSTRACODES DISTRIBUTION New Design Group The following nine genera have been found only in the Renault and Paint Creek formations: Cribroconcha, Hastacyprisj In- cisurella, Tetratylus, Sulcella, Chesterella, OliganisuSj Cyathus, and Coryellina. Four of them, Cribroconcha, Sulcella, Cyathus, and Coryellina, are present in the Pennsyl- vanian, however, and therefore are not re- stricted to the New Design group, and Oli- ganisus is found in the middle Mississippian. The four remaining genera are now known only from the lowest Chester group. The following species have been found only in the Renault and Paint Creek for- mations: Cribroconcha costata n. sp., Incis- urella lata n. sp., Glyptopleura bristoli Croneis and Gutke, Discoidella pendens Croneis and Gutke, Oliganisus geisi Croneis and Gutke, and Moorites elongatus n. sp. Of these /. lata and M. elongatus seem to be good markers for this group, especially the latter, which is quite distinctive. The only other Chester species of Moorites known is from the Vienna. Renault formation. — Of the 31 restricted Renault species, 16 are new. Many of these, together with some of those described by Croneis and Gutke (1939), are too imper- fectly known to serve as good index forms. Few Bairdia are good horizon markers but B. aequa n. sp. seems to possess, in its very flat parallel sides, sufficient differentiation to make it fairy easy to recognize. In the Gyptopleuridae, Glyptopleura henbesti Cro- neis and Gutke, Glyptopleurina longuronis n. sp., Glyptopleuroides girtyi and G. per- plexus Croneis and Gutke are distinctive. Hollinella longispina (Jones and Kirkby), from the Carboniferous limestone of Eng- land and Scotland, seems to be confined to the Renault in Illinois. The genus Chester- ella Croneis and Gutke, represented by C. exuta and C. fissurata, and C.f incerta Correlation of Chester Formations^ Group Standard Section Southwestern Illinois Southeastern Illinois and Western Kentucky Southwestern Indiana West-Central Kentucky Kinkaid fm. Kinkaid fm. Kinkaid Is. & sh. Negli Creek Is. Degonia ss. Degonia ss. Degonia ss. Mt. Pleasant ss. Clore fm. Clore fm. Clore sh. & Is. Gennet Creek sh. Elvira Palestine ss. Palestine ss. Palestine ss. Bristow ss. Leitchfield fm. Menard fm. Menard fm. Menard Is. & sh. Siberia Is. Waltersburg ss. Baldwin fm. Waltersburg ss. Wickcliffe ss. Vienna fm. Tar Springs ss. Vienna Is. & sh. Unnamed sh. Tar Springs ss. Tar Springs ss. Glen Dean fm. Okaw Is. Glen Dean sh.& Is. Glen Dean Is. Glen Dean Is. Horn berg Hardinsburg ss. Hardinsburg ss. Hardinsburg ss. Hardinsburg ss. Golconda fm. Golconda sh. & Is. Golconda Is. Golconda Is. Indian Creek sh. Cypress ss. Rum a fm. Cypress ss. Cypress ss. Cypress ss. Paint Creek fm. Paint Creek fm. Paint Creek sh.& Is. Beech Creek Is. Elwren ss. & sh. New Design Reelsville Is. Bethel ss. Yankeetown cht. Bethel ss. Sample ss. & sh. Girkin Is. Renault fm. Renault fm. Renault Is. & sh. Beaver Bend Is. Mooretown sh. & ss. Paoli Is. Aux Vases ss. Aux Vases ss. a In part after Weller and Sutton, p. 766, 1940. 8 CHESTER OSTRACODES OF ILLINOIS n. sp., is one of the few Chester genera re- stricted to a single formation. Insofar as now known, none of these species are found outside the Renault. The following list contains those species found only in the Renault. Species Restricted to the Renault Formation Monoceratina opima n. sp. *Bairdia aequa n. sp. Bairdia impendere n. sp. Bairdia insolens n. sp. Bairdiolites tenuis n. sp. Bythocypris gibba n. sp. *Bythocypris truncata n. sp. Hastacypris bradyi Croneis and Gutke Incisurella prima n. sp. Macrocypris biconcava Croneis and Gutke Microcheilinella? exilis n. sp. Seminolites ovalis n. sp. Glyptopleura elliptica Croneis and Gutke *GlyptopIeura henbesti Croneis and Gutke *Glyptopleurina longuronis n. sp. Glyptopleurina simulans Croneis and Gutke *Glyptopleuroides girtyi Croneis and Gutke *Glyptopleuroides perplexus Croneis and Gutke. *Hollinella longispina (Jones and Kirkby) Discoidella ampla n. sp. Polytylites ambitus n. sp. Polytylites grovei (Croneis and Gutke) *Chesterella exuta Croneis and Gutke *Chesterella fissurata Croneis and Gutke *Chesterella? incerta n, sp. Knoxina rogatzi Croneis and Gutke Neokloedenella subquadrata Croneis and Gutke Sansabella vinitaensis (Harlton) Proparaparchites fabulus n. sp. Coryellina elegans (Croneis and Gutke) Moorites intermedins n. sp. Paint Creek formation. — Although all re- stricted Paint Creek species are new, several of the 31 should make good horizon mark- ers. Cribroconcha fornicata, possessing char- acteristics of both Healdia and Seminolites^ is a distinctive form not found in any other * Species of probable correlative value. Check List of Chester Ostracode Species^ Illinois Chester Formations" Other Chester Formations'^ Elvira Homberg New Design H • < (U to > "o c >^ Q c 0 c 0 0 u Oh ■i-j 3 C •5PQ Total species 81 74 74 48 40 94 61 67 7 4 32 19 IS 17 10 Kinkaid 51 63 28 70 26 47 18 45 7 24 9 16 7 23 8 22 0 2 10 6 4 2 Clore 28 55 40 54 20 36 15 38 5 17 9 16 4 13 4 11 1 1 7 8 6 1 Menard 26 51 20 50 55 74 32 80 13 45 18 32 8 27 8 22 0 0 8 12 2 2 Vienna 18 35 15 38 32 58 40 83 7 24 17 30 7 23 10 28 0 0 7 7 1 2 Glen Dean .^^ 5 13 13 24 7 18 29 73 21 37 3 10 9 25 0 1 6 5 3 3 Golconda 9 18 9 23 18 33 17 43 20 69 57 61 18 60 20 55 1 1 9 5 1 -7 Paint Creek 7 14 4 10 8 14 7 18 3 10 18 32 30 49 15 42 0 0 5 2 4 0 0 Renault 8 16 4 10 8 14 10 25 9 31 20 35 15 50 36 54 0 1 7 3 2 1 0 a In the first eight vertical columns the upper number in black type at the intersection of the horizontal and vertical columns of any one formation represents the number of species in this formation which are found in other Illinois Chester formations (51 of the 81 Kinkaid species are found in other formations). The figures below the black face numbers show the per cent of the total species present in other formations. The upper figures at the Intersection of other horizontal and vertical columns represent the number of species common to any two formations (e.g., 32 species are common to the Vienna and Menard formations). The lower figure in small type gives the percentage of the species common to any two formations (e.g., the 32 Menard species found in the Vienna repre- sents 58 per cent of the 55 Menard species present in other formations; likewise the 32 Vienna species in the Menard represents SO per cent of the 40 Vienna species present in other formations). 5 In the last seven columns the figures show the number of species from other formations recognized in the Chester of Illinois. RANGE OF CHESTER OSTRACODES 9 formation. Two species of the new Tetra- tyluSj T. ellipticus and T. elongatus, are also characteristic of the Paint Creek. The only other known species of this genus is found in the Menard. Glyptopleurina flex- uosa is sufficiently well marked to be easily recognized. Perprimitia elongata is distin- guished from species of Perprimitia present in other formations by its elongate thin cara- pace. Mooreaf circincta, distinguished by its almost flat subparallel sides bordered by a ridge located well in from the margins, is probably the most distinctive Paint Creek form. Moorites convexus is distinguished from its long-range associates by its tumid ovate dorsal outline and lack of a prominent border around the free margins. The list of restricted Paint Creek species follows : Species Restricted to the Paint Creek Formation Acratia obtusa n. sp. Bairdia curvis n. sp. Bairdiolites vulgaris n. sp. Bythocypris modicus n. sp. Bythocypris ovatus n. sp. *Cribroconcha fornicata n. sp. Healdia menisca n. sp. Healdia minuta n. sp. Healdia radinula n. sp. Seminolites symmetricus n. sp. *Tetratylus ellipticus n. sp. *Tetratylus elongatus n. sp. *Beyrichia sagitta n. sp. Paracavellina opima n. sp. Paracavellina tumida n. sp. Sulcella celsa n. sp. Sulcella nodocosta n. sp. Sulcella ovata n. sp. *Glytopleurina flexuosa n. sp. Ectodemites magnireticulatus n. sp. Ectodemites quadratus n. sp. Kirkbya elongata n. sp. Kirkbyella truncata n. sp. Jonesina equilatera n. sp. *Perprimitia elongata n. sp. Sansabella ampla n. sp. Sansabella elongata n. sp. Sansabella ovata n. sp. Cyathus vetustus n. sp. *Moorea? circincta n. sp. *Moorites convexus n. sp HoMBERG Group Genera restricted to the Romberg group are as follows: Golcondella, Gejfenina, Kloedenella, Knightina, and Tetrasacculus. Kloedenella heretofore has been known in North America only from the Silurian and Devonian, and Tetrasacculus from Middle Devonian strata of Ohio and Michigan. Knightina is a genus found previously in the * species of probable correlative value. Pennsylvanian and Permian of the mid- Continent region. Golcondella and Gef- fenina are not known outside of the Horn- be rg group. The following species are found in both the Golconda and Glen Dean formations but are restricted to the Romberg group. Those marked with an asterisk are suffi- ciently diverse to form good markers. Glyptopleura intermedia Croneis and Gale *Glyptopleurina? bulbosa Croneis and Gale Glyptopleurina ornata (Croneis and Gale) Glyptopleurina simplex Croneis and Bristol *Glyptopleuroides insculptus Croneis and Gale "*Amphissites carinatus n. sp. *Jonesina craterigera (Brady) *Tetrasacculus mirablilis (Croneis and Gale) Golconda formation. — Approximately half of the 36 restricted Golconda species are new, but some of these are sufficiently abundant and distinctive to make good horizon markers. Monoceratina celsalobata n. sp. is distinguished from other species of Alonoceratina by its low thick form and the relatively high position of the spines as seen in lateral view. Beyrichia contracta n. sp. and B. placida Croneis and Gale are Gol- conda species, and the only other Chester representative of this genus is B. sagitta n. sp. from the Paint Creek. Glyptopleura decacostata Croneis and Gale may be recog- nized by the pronounced forward swing and the relatively wide area free of costae at the posterior end. Denisonia brevicosta n. sp. and Z). cirrata n. sp. both possess shells with a pronounced swing, with un- equal ends, and with a relatively short rid^T^e in the middle of the shell. The single Me- nard species lacks the swing, has a long ridge, and has ends of equal height. Other species which seem distinctive are Golcon- della sulcata, Glyptopleura pentacostata, Glyptopleurina vetula, and Geffeninaf praelonga. The complete list of restricted Golconda species follows: Species Restricted to the Golconda Formation *Monoceratina celsalobata n. sp. Bairdia? osorioi Croneis and Gale Bairdia cf. subelongata Jones and Kirkby Bythocypris opima n. sp. Healdia cornigera (Jones and Kirkby) Healdia elliptica n. sp. Healdia mucronata n. sp. Healdia opima n. sp. Seminolites? reversus n. sp. *Beyrichia contracta n. sp. 10 CHESTER OSTRACODES OF ILLINOIS *Beyrichia placida Croneis and Gale Cavellina longula n. sp. Paracavellina elliptica n. sp. *ParacavellLia pinguis n. sp. Golcondella sulcata Croneis and Gale Glyptopleura curvata Croneis and Gale *Glyptopleura decacostata Croneis and Gale *Glyptopleura pentacostata Croneis and Gale Glyptopleurina insignis Croneis and Gale *Glyptopleurina vetula n. sp. Discoidella simplex Croneis and Gale Kirkbya regularia Croneis and Gale Kirkbya cf. reflexa Girty Kirkbya turrita Croneis and Gale Polytylites similis (Croneis and Gale) Polytylites trilobus (Croneis and Gale) *Denisonia brevicosta n. sp. *Denisonia cirrata n. sp. *Geffenina? praelonga n. sp. Jonesina persulcata Croneis and Gale Knightina neglecta Croneis and Gale Knightina pinguoides Croneis and Gale Neokloedenella? magna n. sp. Perprimitia? bicornis Croneis and Gale Sansabella declivis n. sp. Sansabella truncata n. sp. Glen Dean formation. — As in other for- mations, about half of the restricted species of the Glen Dean are of value as index fos- sils. Of the remainder, four are species described by Ulrich (1891) from Kentucky and Illinois and have not been recognized by subsequent workers. Polytylites directus n. sp. is easily recognized because of its un- usually elongated vertical nodes. Acratia mucronata n. sp., Bairdia attenuata Girty, and Kloedenella macer n. sp. are also dis- tinctive of the Glen Dean. Species Restricted to the Glen Dean Formation *Acratia mucronata n. sp. *Bairdia attenuata Girty Healdia caneyensis Harlton *Polytylites directus n. sp. Polytylites tricollinus (Jones and Kirkby) ^Kloedenella macer n. sp. Primitia cestriensis Ulrich Primitia granimarginata Ulrich Primitia simulans Ulrich Moorea granosa Ulrich Elvira Group Nine genera were found to occur exclu- sively in the upper Chester group, namely, Beyrichiopsis, Rlatychilus, Sargentina, Ve- nula, Balantoides, Gillina, Kloedenellina, Pseudoparaparchites, and Carbo primitia. The first, Beyrichiopsis, is known in the Devonian, so it is presumed that species yet undescribed will be found in the older ■Species of probable correlative value. Chester groups. P seudoparaparchites is rep- resented in the Pennsylvanian and Permian, but is unknown below the Elvira. All other genera listed above are restricted to the group. Many species of the Elvira are restricted to two adjacent formations, and in many cases will serve as good index forms when others are not available. These species are given in the following lists, those thought to be of greatest value being marked with an asterisk. Kincaid-Clore Species *Bairdia sinuosa n. sp. Bairdiolites elongatus Croneis and Funk- houser *Bythocypris clorensis Croneis and Funk- houser Macrocypris reginni Coryell and Johnson Glyptopleura alata Croneis and Funk- houser Glyptopleura compta Croneis and Thurman Glyptopleura symmetrica Croneis and Funk- houser Glyptopleurina insculpta (Croneis and Funkhouser) *Venula striata (Croneis and Funkhouser) *Ectodemites tumidus n. sp. *Ectodemites warei (Morey) *Perprimitia funkhouseri Croneis and Thur- man Sansabella harrisi Croneis and Funkhouser Clore-Menard Species Healdia fayettevillensis Harlton Kirkbya aequalis Croneis and Funkhouser *Denisonia cincta Croneis and Bristol Jonesina puncta Morey Menard-Vienna Species Healdia exilis n. sp. Healdia goniapleura Croneis and Bristol ^Glyptopleurina oehersi (Croneis and Bristol) Kirkbya fossula Croneis and Bristol Vienna formation. — Only eight restricted species are found in the Vienna, six of which are new. Of the eight, four are recognized easily, namely, Healdia vinitaensis Harlton, Platychilus ovoides n. sp., Glyptopleurina iniqua n. sp., and Sansabella parallela n. sp. Cavellina parva, Polytylites diversuSj and Moorites brevis, all new species, complete the Vienna list. Menard formation. — At least five of the 19 restricted species in the Menard form good index fossils. Bairdia brevis Jones and Kirkby has an unusually high dorsum, a very long dorso-posterior slope, and a low, sharp posterior termination. Bairdiolites fornica- RANGE OF CHESTER OSTRACODES 11 tus n. sp. has a very highly arched dorsum, is comparatively short, and has a short but somewhat sharp posterior end. Paracavellina ovata n. sp. is the shortest species so far recognized in this genus. G, kayi Croneis and Bristol can be distinguished from other species of Glyptopleura by the ribs which are concave upward just below the pit. Kirkbyella truncata possesses a prominent vertical furrow across the posterior end. Species Restricted to the Menard Formation *Bairdia brevis Jones and Kirkby Bairdia dellcata Morey *Bairdiolites fornicatus n. sp. Macrocypris acuminata n. sp. Macrocypris chapmani Croneis and Bristol Cavellina dispar n. sp. ^Paracavellina ovata n. sp. Glyptopleura carrolli Croneis and Bristol *Glyptopleura kayi Croneis and Bristol Glyptopleura resupinata Croneis and Bristol Ectodemites monomastadis (Coryell and Sohn) Ectodemites parvus n. sp. *Kirbyella truncata n. sp. Polytylites concavus (Croneis and Bristol) Jonesina lalickeri Croneis and Bristol Carboprimitia campa n. sp. Clore formation. — The genus Glypto- pleurdj which reaches its maximum develop- ment in the upper Elvira, has eight species restricted to the Clore. The most distinctive of these is the rectangular G. inoptina Girty, first described from the Fayetteville shale of Arkansas. This species is readily differenti- ated by its characteristic lateral outline, large overlap, and by the median rib which, instead of ending at the pit, bends upward and around the pit, joining the rib next above it. Other particularly distinctive spe- cies are G. multicostata Morey, G. sagae Coryell and Johnson and G. tyri (Coryell and Johnson), Other distinctive forms not known out- side of the Clore are Beyrichiopsis bryfihil- daCj B. thorij Sargentina allani and Loch- riella fenriri, all described by Coryell and Johnson. Polytylites reticulatus n. sp. may be recognized by the high position of the inner carina. The Clore also has a large number of Amphissitinae, which however, are difficult to distinguish specifically and therefore are not good index fossils. Species Restricted to the Clore Formation Bairdiolites ovatus Croneis and Funk- house r Bythocypris amsdenensis Morey *Beyrichiopsis brynhildae Coryell and Johnson *Beyrichiopsis thori Coryell and Johnson Cavellina congruens n. sp. Cavellina hoeniri Coryell and Johnson Cavellina ithunnae Coryell and Johnson Cavellina librata n. sp. ^Sargentina allani Coryell and Johnson Glyptopleura alata Croneis and Funk- houser Glyptopleura elongata n. sp. Glyptopleura friggae Coryell and Johnson ^Glyptopleura inoptina Girty *Glyptopleura multicostata Morey ^Glyptopleura sagae Coryell and Johnson Glyptopleura similis Croneis and Funk- houser *Glyptopleura tyri (Coryell and Johnson) Balantoides moreyi Croneis and Funkhouser Kirkbya marginata Croneis and Funkhouser *Polytylites reticulatus n. sp. Gillina vitharri Coryell and Johnson Jonesina odini Coryell and Johnson Jonesina spinosa Croneis and Funkhouser Kloedenellina heimdalli Coryell and John- . son Lochriella fenriri (Coryell and Johnson) Lochriella reversa (Morey) Perprimitia sigynae (Coryell and Johnson) Sansabella lenticularis n. sp. Sansabella njorthi (Coryell and Johnson) Paraparchites ovatus n. sp. Carboprimitia longula n. sp. Primitia cestriensis caldwellensis Ulrich Primitia subaequata Ulrich Kink aid formation. — The Kinkaid, like the Clore, contains numerous species of the Amphissitinae and Glyptopleura. The for- mer contains the species Amphissites exiguus n. sp., A. rugosus Girty, and Ectodemites primus n. sp., which have the variant char- acteristics necessary to form good horizon markers. Six species of Glyptopleura are restricted to the Kinkaid, G. alvea n. sp. being the most easily recognized by reason of its flattened dorsum and the few thin costae. Other restricted species, all new, in- clude the large thick Acratia tumida, the long slender Bairdia aculeata, and Sargen- tina asulcata. Kirkbya bifrons and Deloia serrata, described by Croneis and Thurman, are also thought to be good horizon markers.. *Species of probable correlative value. * Species of probable correlative value. 12 CHESTER OSTRACODES OF ILLINOIS Species Restricted to the Kinkaid Formation Acratia tumida n. sp. Bairdia aculeata n. sp. Bairdia subtila n. sp. Bairdiolites procerus n. sp. Macrocypris ovata n. sp. Microcheilinella cordata n. sp. *Sargentina asulcata n. sp. Sargentina crassimarginata (Croneis and Thurman) Glyptopleura adunca Croneis and Thurman *Glyptopleura alvea n. sp. Glyptopleura circumcostata n. sp. Glyptopleura reniformis Croneis and Thur- man Glyptopleura teretiformis Croneis and Thurman *Amphissites exiguus n. sp. Amphissites quadratus n. sp. *Amphissites rugosus Girty Balantoides reticulatus Croneis and Thurman Ectodemites elongatus n. sp. *Ectodemites primus n. sp. *Kirkbya bifrons Croneis and Thurman Kirkbya humerosa n. sp. Kirkbya intermedia Croneis and Thurman Polytylites crassus n. sp. Polytylites sublineatus (Croneis and Thur- man) *Deloia serrata Croneis and Thurman Deloia tumida n. sp. Proparaparchites ovatus n. sp. Pseudoparaparchites? aclis Croneis and Thurman CHESTER CORRELATIONS Ostracodes have been described from three Upper Mississipplan formations which crop out in areas outside of the Illinois basin. These are the Amsden formation of Wyo- ming, the Reynolds formation of West Vir- ginia, and the Fayetteville shale of western Arkansas and eastern Oklahoma. These for- mations all appear, from the data now avail- able, to correlate with the upper Chester El- vira group, although the Fayetteville con- tains several species found in the middle and lower groups. In addition to these forma- tions, a few scattered species have been re- ported from the Bell shale of Ontario, the Batesville sandstone of Arkansas, and the Barnett shale of Texas. Amsden formation. — Darton (1904) named the Tensleep and Amsden forma- tions, which occur between the Chugwater and Madison and are exposed along a branch of Tongue River west of Dayton, Wyoming, and considered them to be of Pennsylvanian age. Branson and Greger *Species of probable correlative value. (1918) established the Mississippian age of the Amsden in the Wind River Moun- tains, correlating it with the Ste. Genevieve formation of the Mississippi Valley. Morey (1935) described 17 species of ostracodes from the Amsden, and followed Branson and Greger's correlation. He stated how- ever "that comparatively little on ostracode faunas of this period has been published and, therefore, it is not easy to make exact correlations." Scott (1935), in connection with a discussion of the Big Snowy group of Montana which immediately underlies the Amsden, considered the Amsden fauna "to be more closely related to the Chester fauna than any other. . . . When this fauna is considered in relation to that of the underlying Big Snowy group, and when stratigraphic relationships are taken into consideration, the Amsden of central Mon- tana must be middle or upper Chester in age." A preponderance of the Amsden ostra- code species is found in the upper Chester Clore formation. Of the restricted forms, five Amsden species occur in the Elvira, one in the Homberg and none in the New Design. Although the Amsden fauna is small, the presence of such species in the Clore as Bythocypris amsdenensisj Glypto- pleura m.ulticostatay and Ectodemites warei appears to be particularly significant. Reynolds lirnestone. — The Reynolds, de- fined as a member of the Bluefield forma- tion of the Mauch Chunk "group" by Re- ger (1926), crops out in Monroe County, southeastern West Virginia. It, with the overlying Ada and Talcott members, was considered to be the equivalent of the Clore formation. Coryell and Sohn (1938) de- scribed 13 ostracode species from a shale bed near the top of the formation exposed in a quarry near Morgantown, some dis- tance from the type locality. They attempted no correlation other than that shown on a columnar section which gives the members of the Bluefield and Greenbrier groups. The only tie with the Illinois formations given in the section is the Bethel sandstone which is shown between Fredonia below and Gasper above, and is erroneously corre- lated with the "Meramecan." An examination of topotype material has more than doubled the number of species, bringing the total number of known spe- cies (exclusive of those as yet undescribed) CHESTER CORRELATIONS 13 to 27. While the Reynolds fauna is small, those species found in it are quite distinctive. The present study shows a decided preva- lence of Elvira species, all but one of the restricted species occurring in this group. Within the group there is a dominance of Menard forms. The overlying Talcott and Ada members are probably also referable to the Menard, and the Droop may be equiva- lent to the Palestine as they correspond lith- ologically more closely than do the shaly Webster Springs and Bickett members. The upper Chester age of the Reynolds is shown by the presence of Ectodemites mono- mastadis, Deloia serrata and large numbers of Carboprimitia, among which is found C. depressa Croneis and Funkhouser. The correlation of the Reynolds with the Me- nard, which is high in the type Chester series, raises an interesting speculation as to the West Virginia equivalents of the Clore and Kinkaid, and as to the probable age of the many hundreds of feet of Mauch Chunk beds which must lie above the equivalent of the highest Chester formation of the Illinois basin. Fay etteville shale. — Simonds (1891) de- scribed this formation from outcrops in northwestern Arkansas, but confused it with the Moorefield. Adams and Ulrich (1904) gave the correct position of the formation in the succession and later (1905) the same authors placed the Wedington sandstone in the upper Fayetteville as a member of that formation. Croneis (1930, p. 69), after an exhaustive faunal study, concluded that "although these Arkansan beds may be correlated with parts of the Chester series of Illinois, they are more closely related to such southern formations as the Caney shale of Oklahoma and the upper Gasper, Gol- conda and Bangor formations of Alabama". David White ( 1937 ) , from a study of the fossil plants, determined the age of the Wedington sandstone as upper Chester. Girty (1910) described, but did not figure, 13 new species of ostracodes from the Fay- etteville of Arkansas. Later, Harlton (1929) described 12 species, most of which were new, from the formation in Arkansas and Oklahoma. However, neither Girty nor Harlton attempted correlations with type Chester formations. Half of their species have not been recognized in the Illi- nois Chester, largely because of the lack of illustrations in the former paper. How- ever, an examination of some of Girty's types has overcome a part of this difficulty. Our collections contain about 50 species from Oklahoma and Arkansas and, eliminat- ing new species and duplicates, there remain about 30 species on which correlations can be based. There appears to be close agreement in the distribution of the Oklahoma and Ar- kansas species with respect to the type Chester, each showing two distinct affini- ties, one with the middle Chester (Golcon- da) and the other with the upper Chester (Clore and Kinkaid). The restricted Ches- ter species show that the affinity of the Fayetteville is much closer with the upper Chester than with the Golconda. This cor- relation is in close agreement with the con- clusions of Croneis based on the megafauna, because the Bangor limestone occurs below the Pennington shale. The latter, according to Reger (1926, pp. 311-312) is equivalent to the Hinton and succeeding groups, which may be younger than any formations in the type Chester section. Thus the Bangor of Alabama and Tennessee, the Fayetteville of northeastern Oklahoma and Arkansas, and equivalent portions of the Caney shale of Oklahoma appear to correspond to the Elvira group of Illinois. The Elvira species occurring in the Fay- etteville are as follows, the particularly significant ones being starred. Bairdia aculeata n. sp. Bythocypris clorensis Croneis and Funk- houser Healdia fayettevillensis Harlton Healdia vinitaensis Harlton *Glyptopleura inoptina Girty Glyptopleura multicostata Morey *Amphissites rugosus Girty *Denisonia cincta Croneis and Bristol Lochriella reversa (Morey) Sansabella harrisi Croneis and Funkhouser The most characteristic Fayetteville spe- cies, GraphiadactylUs arkansana (Girty), which outnumbers all others in most of the Oklahoma and Arkansas collections, is not represented by a single specimen in the Chester collection of Illinois and adjacent states that have been studied. Other species of GraphiadactylUs are known from the lower Mississippian (Kinderhook) of south- ern Illinois but these are easily differenti- ated from the Fayetteville species. 14 CHESTER OSTRACODES OF ILLINOIS Faunal Chart ^ U W O ACRONOTELLIDAE \/[r\rtr\np'rcii-\n^ rplQfllona f J3 CoOPPr X X X X X X X X X X X X X X X X X X X X X X X X X cf. cf. X X X _ X X X X X X X cf. cf. X X X X X X X X X X X X X X X X X cf. X X X X X X X X X X X X X X X X X X X 6 IVTrM-inr'^rpf-i n^ nnima Clonnpr BAIRDIIDAE Ai^rafia Hicinnrfa A/Tnrpv 7 Ar'rot-ia mnpronflt"3 Cnnnpf 6 3 4 34 7 Bairdia curvis Coooer 7 Bairdia salei Croneis and Thurman. .... . Bairdia golcondensis Croneis and Gale 3 Bairdia granireticulata Harlton . . 3 4 Bairdia imDendere CooDer . ... Bairdia insolens Cooper Bairdia lanulata Harlton 4 Bairdia mccoyi Croneis and Gutke Bairdia nasuta Morey 7 Bairdia? osorioi Croneis and Gale Bairdia renaultensis Croneis and Gutke Bairdia sinuosa Cooper Bairdia subelongata Jones and Kirkby 8 Bairdia subtila Cooper Bairdia submucronata (Jones and Kirkby) 3, 8 Bairdia? subrotundata Harlton 3 Bairdiolites brevirostris Croneis and Thurman Bairdiolites bulbosus Croneis and Bristol Bairdiolites crassus Cooper . . . Bairdiolites crescentis Croneis and Gale Bairdiolites elongatus Croneis and Funkhouser Bairdiolites fornicatus Cooper . Bairdiolites ovatus Croneis and Funkhouser Bairdiolites platypleurus Croneis and Gale r — Bairdiolites procerus Cooper ' Bairdiolites tenuis Cooper 4 Bairdiolites vulgaris Cooper Beyrichiopsis brynhildae Coryell and Johnson Beyrichiopsis thori Coryell and Johnson — Bythocypris amsdenensis Morey 4, 7 Bythocypris clorensis Croneis and Funkhouser Bythocypris concava Cooper 3 Bythocypris fabalis Cooper Bythocypris fayettevillensis Harlton 4 Bythocypris gibba Cooper. Bythocypris modica Cooper FAUN AL CHART 15 Species J^ c tu o i^ Bythocypris opima Cooper .... X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Bythocypris ovata Cooper Bythocypris truncata Cooper Cribroconcha conspicua (Harlton) 3 Cribroconcha costata Cooper. . Cribroconcha fornicata Cooper Hastacypris bradyi Croneis and Gutke Healdia aequabilis Cooper Healdia bluefieldiana Coryell and Sohn. 6 Healdia caneyensis Harlton Healdia cornigera (Jones and Kirkby) 8 Healdia elliptica Cooper Healdia exilis Cooper 6 Healdia fayettevillensis Harlton 3 Healdia goniapleura Croneis and Bristol Healdia menisca Cooper Healdia minuta Cooper Healdia mucronata Cooper Healdia opima Croneis and Gale Healdia ornata Morey 6 7 Healdia ovoidea Cooper Healdia radinula Cooper Healdia simplex Roundy 6 Healdia subcarinata Morey Healdia tenuicosta Cooper 7 Healdia vinitaensis Harlton 3 Incisurella lata Cooper Incisurella prima Cooper Macrocypris acuminata Cooper Macrocypris biconcava Croneis and Gutke — Macrocypris chapmani Croneis and Bristol . . . Macrocypris ovata Cooper Macrocypris reginni Coryell and Johnson Microcheilinella cordata Cooper Microchellinella? exilis Cooper Microcheilinella obesa Cooper Microcheilinella pergracills Croneis and Gale Microcheilinella subcorbuloides (Jones and Kirkby) . . Microcheilinella tumida Cooper 3 Seminolites ovalls Cooper Seminolites? reversus Cooper Seminolites sohni Croneis and Bristol Seminolites symmetricus Cooper. 3 Tetratylus ellipticus Cooper Tetratylus elongatus Cooper. Tetratylus menardensis (Croneis and Bristol) BEYRICHIIDAE Beyrichia contracta Cooper Beyrichia placida Croneis and Gale Beyrichia sagitta Cooper 6 16 CHESTER OSTRACODES OF ILLINOIS Species ^ OJ c ^ OS 3 C (U o CYTHERELLIDAE Cavellina bransoni (Morey) X X X X X X cf. X X X X X X X X X X X X X X X X X X X X X X X X X X X cf. X X X X X X X X cf. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 7 Cavellina dispar Cooper. 6 Cavellina geisi (Croneis and Gale) Cavellina glandella (Whitfield) 2 Cavellina hoeniri Coryell and Johnson Cavellina ithunnae Coryell and Johnson Cavellina longula Cooper Cavellina ovatiformis (Ulrich) 3 Cavellina parallela Croneis and Gutke Cavellina parva Cooper . . 6 Cavellina perplexa Croneis and Funkhouser Cavellina spatulata Croneis and Gutke Paracavellina elliptica Cooper Paracavellina opima Cooper 4,6 Paracavellina ovata Cooper Paracavellina pinguis Cooper .... Paracavellina tumida Cooper Platychilus ovoides Cooper .... — Sargentina allani Coryell and Johnson Sargentina asulcata Cooper — Sargentina crassimarginata (Croneis and Thurman) . . Sulcella celsa Cooper — Sulcella nodocosta Cooper . Sulcella ovata Cooper DREPANELLIDAE Cornigella golcondensis (Croneis and Gale) . . Golcondella sulcata Croneis and Gale GLYPTOPLEURIDAE Glyptopleura adunca Croneis and Thurman • Glyptopleura alata Croneis and Funkhouser Glyptopleura alternata Croneis and Funkhouser. . . . • Glyptopleura alvea Cooper Gluptopleura angulata Girtv 4 Glyptopleura bristoli Croneis and Gutke Glyptopleura carrolli Croneis and Bristol Glyptopleura circumcostata Cooper ■ Glyptopleura complexa Croneis and Funkhouser Glyptopleura compta Croneis and Thurman Glyptopleura conflexacostata Croneis and Gale Glyptopleura.^ curvata Croneis and Gale .... — Glyptopleura decacostata Croneis and Gale Glyptopleura elliptica Croneis and Gutke Glyptopleura elongata Cooper " Glyptopleura friggae Coryell and Johnson . . — Glyptopleura gibba Croneis and Gale Glyptopleura harltoni Croneis and Bristol . . Glyptopleura henbesti Croneis and Gutke . . . FAUN AL CHART 17 Species J< ^ U t^ Glyptopleura inoptina Girty . Glyptopleura intermedia Croneis and Gale. . . . Glyptopleura kayi Croneis and Bristol Glyptopleura kellettae Croneis and Thurman Glyptopleura multicostata Mbrey . . . Glyptopleura cf. pentacostata Croneis and Gale Glyptopleura pseudosulcata Croneis and Thurman. . . Glyptopleura reniformis Croneis and Thurman Glyptopleura resupinata Croneis and Bristol Glyptopleura sagae Coryell and Johnson Glyptopleura schizopleura Coryell and Sohn Glyptopleura similis Croneis and Funkhouser Glyptopleura spinosa (Jones and Kirkby) Glyptopleura symmetrica Croneis and Funkhouser. . . Glyptopleura teretiformis Croneis and Thurman. . . . . Glyptopleura tyri (Coryell and Johnson) Glyptopleura variacostata Croneis and Thurman . . . . Glyptopleura varians Croneis and Funkhouser Glyptopleura venosa (Ulrich) Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina Glyptopleurina .^ bulbosa Croneis and Gale complexa Croneis and Bristol coryelli Croneis and Gutke . . flexuosa Cooper iniqua Cooper. insculpta (Croneis and Funkhouser) . . insignis (Croneis and Gale) longuronis Cooper oehersi (Croneis and Bristol) ornata (Croneis and Gale) simplex Croneis and Bristol ....... simulans Croneis and Gutke simulatrix (Ulrich) vetula Cooper Glyptopleuroides girtyi Croneis and Gutke ... Glyptopleuroides insculptus Croneis and Gale. Glyptopleuroides perplexus Croneis and Gutke Mesoglypha mediocre Cooper ........... Venula striata (Croneis and Funkhouser). GRAPHIADACTYLLIDAE Graphiadactyllis arkansana (Girty) Graphiadactyllis tenuis Cooper. . . . HOLLINELLIDAE Hollinella granifera (Ulrich) HolHnella longispina (Jones and Kirkby) Hollinella radiata (Jones and Kirkby). . . KIRKBYIDAE Amphissites carinatus Cooper Amphissites chappelensis Roundy Amphissites exiguus Cooper Amphissites golcondensis Croneis and Gale Amphissites insignis Croneis and Thurman . 0 3.7. 18 CHESTER OSTRACODES OF ILLINOIS Species C u c o o o c a Q c c El > hi<;«;lfphicci f(=Q nnarlratiis C-OODpr 3,4 A mnViiccif PI qiitidIpv fCrirtVI 4 Balantoides moreyl Croneis and Funkhouser RTlanfoirles auadrilobus Morev 7 Balantoides reticulatus Croneis and Thurman T^iQmidplla amnla Coonpr Ectodemites bicarinatus (Croneis and Thurman) .... Ectodemites costelliferus (Croneis and Bristol) Frtodemites elono'atus CooDer — Ectodemites masnireticulatus Cooper Ectodemites monomastadis (Coryell and Sohn) Ectodemites obesus (Croneis and Gale) 6 Frtodemites obloneus (Tones and Kirkbv) 8 Frtodemites oblonsfus transversalis (Girtv) 3 7 7 Kirkbya aequalis Croneis and Funkhouser Kirkbya elongata Cooper Kirkbya humerosa Cooper Kirkbya intermedia Croneis and Thurman. Kirkbya marginata Croneis and Funkhouser Kirkbya cf. reflexa Girty 3 Kirkbya regularia Croneis and Gale Kirkbya symmetrica Croneis and Thurman Kirkbya turrita Croneis and Gale . . Kirkbyella gutkei Croneis and Bristol . . Kirkbyella quadrata Croneis and Gutke . . Kirkbyella sulcata Cooper Kirkbyella truncata Cooper Polytylites ambitus Cooper Polytylites biforatus (Croneis and Thurman) Polytylites bradfieldi (Croneis and Funkhouser) Polytylites concavus (Croneis and Bristol) . . — Polytylites crassus Cooper Polytylites directus Cooper Polytylites diversus Cooper .... . Polytylites elongatus (Croneis and Bristol) Polytylites fossilis (Croneis and Thurman) , Polytylites geniculatus Cooper . . Polytylites grovei (Croneis and Gutke) Polytylites nodobliquus (Croneis and Gale) Polytylites quincollinus (Harlton) 3 Polytylites reticulatus Cooper . . Polytylites similis (Croneis and Gale) FAVNAL CHART 19 Species _bd OJ c rt rt 3 G o U 15 Poly tylites sublineatus (Croneis and Thurman) Polytylites superus (Croneis. and Gale) . x X X X X X X X X X X X X X X X X X X X X X X X X X X ? X X X X X X X X X X X ? X cf. X X X X X X X X X X X X — Polytylites tricollinus (Jones and Krikby) 8 Polytylites trilobus (Croneis and Gale) Polytylites wilsoni (Croneis and Gutke) Savagella? acuminata Cooper Savagella lindahli (Ulrich) . Savagella rhomboidalis (Girty) 1 2 KLOEDENELLIDAE Chesterella exuta Croneis and Gutke Chesterella fissurata Croneis and Gutke Chesterella? incerta Cooper . . Deloia serrata Croneis and Thurman 6 Deloia spinosa Croneis and Bristol Deloia sulcata Croneis and Funkhouser 1 Deloia tumida Cooper Denisonia brevicosta Cooper Denisonia cincta Croneis and Bristol 4 Denisonia cirrata Cooper GefFenina johnsoni Coryell and Sohn 6 Geffenina marmerae Coryell and Sohn 6 Geffenina? praelonga Cooper Geffenites jungae Coryell and Sohn 6 Geffenites mammoides Coryell and Sohn 6 Gillina vitharri Coryell and Johnson Jonesina craterigera (Brady) Jonesina equilatera Cooper Jonesina intermedia Croneis and Bristol Jonesina lalickeri Croneis and Bristol Jonesina odini Coryell and Johnson Jonesina persulcata Croneis and Gale . . Jonesina puncta Morey. 7 Junesina reticulata Harlton 4 Jonesina spinigera Cooper. Jonesina spinosa Croneis and Funkhouser Jonesina tenuisinuosa Cooper — Kloedenella macer Cooper Kloedenellina heimdalli Coryell and Johnson Knightina neglecta Croneis and Gale — Knightina pinguoides Croneis and Gale Knoxina inflata Croneis and Gale Knoxina rogatzi Croneis and Gutke Lochriella fenriri (Coryell and Johnson) . Lochriella reversa (Morey) Neokloedenella? magna Cooper ■ 3,6 20 CHESTER OSTRACODES OF ILLINOIS Species 3 1) d c PL. d 8 'o O c OS tu Q c o c c > -a a 0 6 Neokloedenella prima Croneis and Funkhouser Neokloedenella secunda Croneis and Bristol X X X X X X X ? X X X X X X X X cf. X X X X X X X X X X X X X X X cf. X X X X X X X p X X cf. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 1 '^ 6 6 Neokloedenella subquadrata Croneis and Gutke Olio'anisus 2eisi Croneis and Gutke Perprimitia'^ bicornis Croneis and Gale Perprimitia elongata Cooper Perprimitia funkhouseri Croenis and Thurman Perprimitia matheri Croneis and Bristol — Perprimitia robusta Croneis and Gale ....:. Perprimitia sigynae (Coryell and Johnson) . .... Perprimitia tenera Cooper ... Perprimitia turrita Croneis and Gutke . . . Sansabella ampla Cooper .... Sansabella amsdenensis Morey . . 7 Sansabella bradfieldi (Coryell and Sohn) 3,6 Sansabella declivis Cooper . . Sansabella? dubia Morey / Sansabella elongata Cooper Sansabella harrisi Croneis and Funkhouser 3 Sansabella lenticularis Cooper Sansabella njorthi (Coryell and Johnson) Sansabella ovata Cooper Sansabella parallela Cooper Sansabella sulcata Roundy. 1,^ Sansabella truncata Cooper Sansabella tumida Coryell and Sohn . 6 Sansabella vinltaensis (Harlton) 3,4 LEPERDITELLIDAE Cyathus vetustus Cooper .... Microcoelonella scanta Coryell and Sohn 6 Microparaparchites erectus Cooper Microparaparchites inornatus Croneis and Bristol . . . Microparaparchites spinosus Croneis and Gale Paraparchites cyclopeus (Girty) 3 Paraparchites gibbus Bell 5 Paraparchites inornatus (McCoy) 3 Paraparchites kinkaidensis Croneis and Thurman Paraparchites nicklesi (Ulrich) . \6,7 Paraparchites ovatus Cooper Proparaparchites fabulus Cooper Proparaparchites ovatus Cooper Pseudoparaparchites? aclis Croneis and Thurman. . . . PRIMITIIDAE Carboprimitia campa Cooper — Carboprimitia depressa Croneis and Funkhouser Carboprimitia longula Cooper . . 6 Carboprimitia rotunda Croneis and Funkhouser Carboorimitia simulans Croneis and Bristol — FAUN AL CHART 21 Species M o U s Coryellina elegans (Croneis and Gutke) X X X cf. X X X X X X p ? X X X X X _ X ? X X Halliella? retiferiformis Girty 3 Primitia cestriensis Ulrich Primitia cestriensis caldwellensis Ulrich Primitia fayettevillensis Girty Primitia granimarginata Ulrich 3 Primitia seminalis Girty 1,2,3 Primitia simulans Ulrich Primitia subaequata Ulrich Tetrasacculus mirablilis (Croneis and Gale) YOUNGIELLIDAE Moorea? circincta Cooper Moorea granosa Ulrich Moorites brevis Cooper Moorites convexus Cooper Moorites elongatus Cooper Moorites intermedius Cooper Moorites jhomboidalis (Croneis and Bristol) . 3,6 "The last column shows scattered occurrences outside of Illinois, as follows: 1. Barnett shale, San Saba County, Texas; 2. Batesville sandstone, Arkansas; 3. Fayetteville shale, Arkansas; 4. Fayetteville shale, Oklahoma; 5. Lower Windsor series, Ontario; 6. Reynolds (Mauch Chunk) formation, Morgantown, West Virginia; 7. Amsden formation, Wyoming; and 8. Lower Carboniferous formations, Great Britain. 22 CHESTER OSTRACODES OF ILLINOIS COLLECTING LOCALITIES 1. SW. 14 NW. J4 sec. 30, T. 7 S., R. 6 W., Randolph County, Illinois. Glen Dean for- mation (just below upper ledge of Okaw limestone). Collection No. 50. 2. SW. yi sec. 4, T. 6 S., R. 8 W., Randolph County. Illinois. Paint Creek formation along Mississippi River bluffs. Collection No. 155. 3. SE. % NE. 14 sec. 20. T. 12 S.. R. 3 E., John- son County, Illinois. Kinkaid formation, Yo mile south of Veatch school. Collection No. 320. 4. SE. 14 SW. ^ sec. 15, T. 7 S., R. 6 W., Randolph County, Illinois. Clore forma- tion. Collection No. 152. 5. NE. ^ NW. ^ sec. 30 and SE. >4 SW. ^ sec. 19, T. 12 S., R. 5 E., Pope County, Illinois. Kinkaid formation in railroad cut at Robbs. Collection Nos. 7, 314. 6. NE. 14 SW. % sec. 35,^T. 8_ S., R. 4 W., Jackson County, Illinois. Kinkaid forma- tion in abandoned quary. Collection No. 53. 7. SE. 14 SW. ^ sec. 28, ^T. 11 S., R. 1 W., Union County, Illinois. Menard forma- tion. Collection No. 157. 8. NE. y4 NW. 14 sec. 20, T. 5 S., R. 8 W., Randolph County, Illinois. Golconda for- mation, on east side of new highway bridge. Collection No. 156. 9. SE. ^ SW. % sec. 11, T. 12 S., R. 7 E., ^^ mile south of Eichorn, Hardin County, Il- linois. Renault formation. Collection No. 4. 10. SE. 14 SW. 14 sec. 26, T. 11 S., R. 1 W., Union County, Illinois. Vienna formation. Collection No. 160. 11. NW. 1/4 NW. ^ sec.^ 15, T. 11 S., R. 9 E., Hardin County, Illinois. Glen Dean for- mation. Collection No. 310. 12. NW. % NW. % sec. 3, T. 14 S., R. 3 E., Massac County, Illinois. Renault forma- tion. Collection No. 328. 13. NE. ^ SW. % sec. 9, T. 12 S., R. 1 W., Union County, Illinois. Renault formation. Collection No. 304. 14. NE. 14 SW. li sec. 23, T. 4 S., R. 9 W., Monroe County, Illinois. Renault forma- tion. Collection No. 153. 15. SW. 14 NE. % sec. 1, T. 13 S., R 4 E., Johnson County, Illinois. Menard forma- tion at south entrance to railroad tunnel. Collection No. 322. 16. SW. 1/4 NW. 14 sec. 13, T. 12 S., R. 1 W., Union County, Illinois. Golconda forma- tion. Collection No. 307. 17. SW. 14 SE. 1/4 sec. 5, T. 13 S., R. 7 E., Pope County, Illinois. Type locality Golconda formation in Ohio River bluff near Rock Quarry school. Collection No. 318. 18. SE. 14 SW. 1/4 sec. 32, T. 5 S., R. 8 W., Randolph County, Illinois. Okaw (Golcon- da) and Paint Creek formation. Collec- tion No. 49. 19. NE. 14 SW. y4 NW. 1/4 sec. 28, T. 13 S., R. 3 W., Johnson County, Illinois. , Gol- conda formation. Collection Nos. 40, 324. 20. NW. % NE. 34 sec. 2, T. 7 S., R. 7 W., Ran- dolph Countv, Illinois. Menard formation. Collection No. 313. 21. SE. cor. 1-30, 9 miles east of Greenville, Muhlenberg County, Kentucky. Phillips- Shearn No. 3, Golconda and Paint Creek formations, well cuttings. Collection No. 32. 22. NW. ^ NW. ^ sec. 3, T. 14 S., R. 6 E., Pope County, Illinois. Golconda forma- tion in road cut 0.8 mile north of Hora- berg. Collection No. 315. 23. SW. ^ NW. 14 NW. 14 sec. 27, T. 6 S., R. 6 W., Randolph County, Illinois. Bad- ger-Schroeder No. 1, well cuttings. Col- lection No. 2995 (Subsurface Division). 24. NE. >4 NW. 14 SE. ^ sec. 16, T. 4 S., R. 2 E., Jefferson County, Illinois. Bene- dum-Trees Jefferson No. 1, core samples. Paint Creek formation, depth 2454. Col- lection No. 14. 25. SW. J4 SE. }i sec. 5, T. 13 S., R. 8 E., Hardin County, Illinois. Renault (Shetlerville?) formation, at loading docks for fluorspar southwest of Rosiclare. Collection No. 309. 26. SW. 14 SE. % sec. ^34, T. 11 S., R. 1 W., Union County, Illinois. Clore formation. Collection No. 161. 27. CWL., SW. ^ sec. 33, T. 10 S., R. 8 E., Gallatin County, Illinois. Clore forma- tion. Collection No. 150. 28. W. ^ SW. ^ NW. ^ sec. 5, T. 6 S., R. 1 W.. Perry County, Illinois. H. Forester No. 1 core; top Kinkaid formation (618 ft.) to base Renault (1458 ft.). Collection No. 2. 29. NE. 14 NE. y sec. 26, T. 25 N., R. 20 E., Oklahoma. Fayetteville shale. Collection No. 207. 30. SE. y SW. % sec. 2, T. 7 S., R. 7 E., Ran- dolph County, Illinois. Menard forma- tion. Collection No. 312. 31. North end of cut along Frisco Railroad, be- tween Maple and Douglas streets, Fayette- ville, Arkansas. Upper Fayetteville shale. Collection No. 209. 32. SW. y SW. % sec. 29, T. 7 S., R. 6 W., Randolph County, Illinois. Menard for- mation. Collection No. 51. 33. Near cen. sec. 27, T. 17 N., R. 29 W., north- east of Fayetteville, Arkansas. Habberton collecting locality, near base of Fayetteville shale. Collection No. 211. 34. S. of cen., SE. ^ sec. 16. T. 17 N., R. 29 W., northeast of Fayetteville, Arkansas. U. S. G. S. green loc. 1339a. 35. Greer quarry, 6% miles southeast of Mor- gantown. West Virginia. Near top of Reynolds formation, Mauch Chunk series. Collection No. 31. 36. NW. % SE. % sec. 12, T. 13 S., R.^ 4 E., Johnson County, Illinois. On west side of railroad cut 50 feet north of "RW" post. Vienna formation. Collection No. 325. 37. NW. 14 SW. % NE. y sec. 33, T. 7 S., R. 6 W., Randolph County, Illinois. Quar- ry 3^ miles southeast of Chester. Clore formation. Collection No. 52. 38. SW. 14 SE.^ SE. 1/4 sec. 5, T. 13 S., R. 7 E., Pope County, Illinois. Steep ravine ^ mile east of Rock Quarry School. Type localitv of Golconda formation. Collection No. 9." 39. NW. % NE. 14 NW. ^ sec. 22, T. 6 S., R. 6 W., Randolph County, Illinois. Small quarry, south bank Mary's River. Clore formation. Collection No. 311. ACRONOTELLIDAE 23 SYSTEMATIC DESCRIPTION Three hundred and twenty-five species and one variety of ostracodes have been identified from the Chester series in Illinois, 126 of which are newly described in this report. All but 38 species and one variety of the previously described forms are repre- sented in our collections. Descriptions of the new species are presented in the follow- ing pages together with redescriptions of 37 species known from other areas (including two from western Kentucky) which have been recognized in Illinois for the first time. In addition descriptions of two species from the Fayetteville shale, one of them new, and two species from the Reynolds formation of the Mauch Chunk series are included for purposes of comparison. One new sub- family and 10 new genera are proposed. Illustrated on the plates are all of the new species, 117 species described by Croneis and associates and by Coryell and Johnson that are present in our collections, and 45 species described from other areas, all but four of which are known in Illinois. The dimensions listed in the following descriptions refer to the holotypes of new species and the principal figured specimens of others. Family Acronotellidae Swartz Genus Monoceratina Roth MONOCERATINA CELSALOBATA Cooper, n. sp. Plate 1, figures 23-26 Carapace elongate in lateral view, very thick; ends rounded with a slight forward swing; cardinal angles obtuse; dorsum and venter very slightly convex, subparallel ; ventral lobe terminates just above the ven- tral margin and about the middle of the posterior half; hinge straight; greatest height and thickness just back of midlength ; pit indistinguishable. Length, 0.83 mm; height, 0.30 mm; thickness, 0.37 mm. Golconda formation, locality 17, rare. M. cehalobata is distinguished from M. furcula Croneis and Gale by the greater proportional length (form ratio) and by the relatively high position of the lobes. Monoceratina opima Cooper, n. sp. Plate 1, figures 29-32 Carapace short and thick, valves equal, elongate in lateral view, ovate to acumin- ate In ventral view; cardinal angles fairly prominent, anterior more obtuse, posterior of about 90 degrees, giving a slight forward swing; dorsum slightly convex, venter broadly so ; hinge straight and slightly chan- nelled ; lobes terminate at and conform to ventral margin; greatest height and thick- ness back of midlength. Length, 0.59 mm; height, 0.30 mm; thickness, 0.37 mm. Renault formation, locality 9, rare. This species Is distinguished by Its short, thick carapace and by the conformation of the spine-like lobe and the ventral margin. Genus Triceratina Upson Triceratina Upson, 1933, Nebraska Geol. Survey, Bull. 8, p. 29. Monoceratina (part) Kellett, 1935, Jour. Paleon- tology, vol. 9, p. 157. Pterocodella (part) Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 40. The presence of a trinodal ostracode In the basal Chester, described by Croneis and Gutke as Pterocodella inconsueta, throws an Interesting light upon Upson's genus Triceratina. The Chester species possesses a large, prominent posterior node In addition to the splne-termlnated ventral node, and a somewhat less prominent but wider dorsal node or swelling, the latter situated above the ventral node. The Chester specimens show these nodes to be quite constant, especially the ventral and dorsal ones, and therefore the question of the synonymy of these forms should be reopened. Bassler and Kellett (1934, p. 12) say that "Good generic characters are found In the loba- tlon of the valve. . . . and variations In their development always afford good specific characters, and often distinguish genera" — the latter referring to lobes of the Bey- rich I ace a. M. lewisi Harris and Lallcker agrees with the Renault species In all major fea- tures, differing only In minor structural de- tails. While the shape, size, number, and position of nodes vary considerably between young moults and adult specimens, the pre- sence of such prominent nodes on these species is significant. The occurrence, in the lowest Chester, of a species so similar to one from the highest Pennsylvanlan and Permian beds, is Important In that it 24 CHESTER OSTRACODES OF ILLINOIS establishes the persistence of this genus throughout a considerable period of time. The common Chester Monoceratina agrees closely in general structural features and ornamentation with Roth's genotype from the lower Pennsylvanian. Triceratina inconsueta (Croneis and Gutke) Plate 1, figures 4-8 Pterocodella inconsueta Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 40, pi. 1, figs. 7-9, Renault formation. Length, 0.52 mm; height, 0.25 mm; thickness, 0.26 mm. Renault formation, locality 9, rare; Men- ard formation, locality 20, rare. The specimen illustrated is a topotype and is identical with the holotype, except for the somewhat greater swelling above the ven- tral lobe. This species resembles Monocera- tina lewisi Harris and Lalicker from the Fort Riley limestone in its similarly sharp- ended ventral lobe and prominently rounded posterior lobe. Its dorsal swelling corresponds to the dorsal lobe of the latter species but it differs in possessing a more acuminate anterior end in lateral view and in the presence of a tubercle in the postero- dorsal angle. Family Bairdiidae Sars Genus Acratia Delo AcRATiA MUCRONATA Cooper, n. sp. Plate 1, figures 40-42 Carapace long thin and smooth, lens-like in outline; ends sharply pointed and low (near ventral margin), the posterior end produced downward ; hinge line straight or very slightly curved in centro-dorsal region, but not depressed as in A. tumida; articu- lation on ventral margin broadly but slight- ly curved ; surface smooth. Length, 0.98 mm; height, 0.39 mm; thickness, 0.44 mm. Glen Dean formation, locality 1, rare. Acratia obtusa Cooper, n. sp. Plate 1, figures 1-3 Carapace large, elongate, thick and smooth ; ends abruptly terminated without the tapering characteristic of other species; hinge straight, but not depressed; left valve slightly overlaps the right around en- tire margin except in the centro-dorsal por- tion ; posterior end slightly produced down- ward. Length, 0.80 mm; height, 0.35 mm; thickness, 0.38 mm. Paint Creek formation, locality 2, rare. Acratia tumida Cooper, n.sp. Plate 1, figures 35-37 Carapace large, oval or lens-shaped in outline; thicker than wide, with largest dimensions central ; centro-dorsal region slightly flattened ; hinge line slightly de- pressed and strongly curved ; left valve overlaps entire free margin, with greatest overlap ventral ; hinge line strongly curved toward left in centro-dorsal portion; sur- face smooth. Length, 1.10 mm; height, 0.58 mm; thickness, 0.58 mm. Kinkaid formation, locality 3, common. Genus Bairdia McCoy Bairdia aculeata Cooper, n. sp. Plate 1, figures 47-48 Bairdia sp. Jones and Kirkby, 1879, Quart. Jour. Geol. Soc. London, vol. 35, pi. 32, figs. 7, 8, Carboniferous of Great Britan. Carapace large, with extremely long and straight postero-dorsal slope with inclination of 30-35° starting forward of the middle of the shell ; dorsal overlap very conspicuous, that on venter much less so ; point low and thin ; hinge sinuous in dorsal view ; greatest height forward of center. Length, 1.10 mm; height, 0.51 mm; thickness, 0.39 mm. Kinkaid formation, locality 3, common. B. aculeata differs from other described species in the long postero-dorsal slope, oc- cupying about three-fifths of the dorsal margin. The nearest known described form is the one figured 2iS Bairdia sp. by Jones and Kirkby from Fife. Bairdia aequa Cooper, n. sp. Plate 1, figures 21-22 Carapace ovate, short and thick, with prominent antero-dorsal shoulder produc- ing abrupt break in the curvature at this point ; anterior end rounded ; posterior end short and blunt ; postero-dorsal slope about 60° ; overlap most prominent along venter; hinge area depressed ; greatest height for- ward of center; sides distinctly flattened in dorsal view; surface appears finely pitted. BARIDIIDAE 25 Length, 0.85 mm; height, 0.49 mm; thickness, 0.38 mm. Renault formation, locality 13, common. This species may be distinguished by its flat, almost parallel sides. Bairdia attenuata Girty Plate 1, figures 33-34 Bairdia attenuata Girty, 1910, Ann, New York Acad. Sci., vol. 20, p. 237, Fayetteville shale. Carapace very long and thin; central portion of ventral margin almost straight, upturned strongly to meet ends; anterior extremity rounded, posterior produced to sharp point directed slightly upward ; ex- tremities slightly belov^^ middle; dorsum convex in middle, sloping towards ends ; postero-dorsal slope very low (35-40°). Length, 1.0 mm; height, 0.46 mm; thick- ness, 0.29 mm. Glen Dean formation, locality 1, common. Although no figures of the type from the Fayetteville shale of Arkansas have been published, the Glen Dean form, by com- parison with the holotype, is so close to it that there is little uncertainty concerning this identification. Bairdia brevis Jones and Kirby Plate 1, figures 11-12 Bairdia hre'vis Jones and Kirkby, 1867, Trans. Geol. Soc. Glasgow, vol. 2, p. 221; 1879. Geol. Soc. London, Quart. Jour., vol. 35, p. 575, pi. 31, figs. 1-8. Carboniferous of Great Britain. — Latham, 1932, Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, p. 377, Car- boniferous of Scotland. Carapace high and thick ; strongly con- vex, dorsum highly arched, forming extrem- ely long postero-dorsal slope inclined about 45°; posterior point very low, venter straight in middle and curved to meet ends ; surface granulose. Length, 1.0 mm; height, 0.60 mm; thickness, 0.43 mm. Menard formation, locality 15, common. Bairdia cestriensis Ulrich Plate 1, figures 27-28 Bairdia cestriensis Ulrich, 1891, Cincinnati Soc. Nat. Hist, Jour., vol. 13, p. 210, pi. 17, figs. 6a-c, Chester series. — Girty, 1915, U. S. Geol. Survey, Bull. 595, p. 39, pi. 2, fig. 10, Bates- ville sandstone. Bairdia cestriensis granulosa Girty, 1910, Ann. New York Acad. Sci., vol. 20, p. 237, Fayette- ville shale. Bairdia cooperi Croneis and Gale, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 287, pi. 6, figs 11, 12, Golconda formation. Length, 1.45 mm; height, 0.73 mm; thickness, 0.58 mm. Renault formation, locality 12, abundant; Golconda formation, locality 19, abundant; Glen Dean formation, locality 1, rare; Men- ard formation, locality 7, rare. This species presumably described from the Glen Dean limestone near Grayson Springs, Kentucky, appears to be identical with forms found in the Renault, Golconda, Glen Dean, and Menard formations in the Illinois Chester and the lower Fayetteville of Arkansas. The granulose surface of Girty's specimens appears to be due to the character of the preservation. Bairdia curvis Cooper, n. sp. Plate 1, figures 43-44 Carapace elongate, tumid ; ends rounded ; dorsum arched, meeting anterior margin in smooth curve, posterior slope 45°, venter strongly concave, giving entire shell a de- cidedly bowed appearance. Length, 1.14 mm; height, 0.46 mm; thickness, 0.41 mm. Paint Creek formation, locality 32, depth 1304-1343 feet, common. This species lies between B. hisingeri (Miinster) and B. suhelongata Jones and Kirkby; it is shorter and more rounded on the ends than the former; and higher and more bowed than the latter species. It is known only from the Golconda and Paint Creek formations from the wells in Muh- lenberg County, where it is found associated with two species of Bythocypris. Bairdia delicata Morey Plate 1, figures 45-46 Bairdia delicata Morey, 1935, Jour. Paleontology, vol. 9, p. 480, pi. 54, figures 14, 16, Amsden formation. Carapace elongate, tenuous ; overlap most prominent along dorsal and ventral mar- gins; venter straight, dorsum curving almost equally toward each end, anterior curve slightly more abrupt; antero-dorsal slope somewhat pronounced, forming angle at junction with anterior margin; posterior slope low (about 45°). Length, 0.71 mm; height, 0.31 mm; thickness, 0.24 mm. Menard formation, locality 20, common. 26 CHESTER OSTRACODES OF ILLINOIS Bairdia granireticulata Harlton Plate 1, figures 17-20 Bairdia giumircticulata Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 267, pi. 2, figs. 10 a, b, Fayetteville shale. Carapace tumid; dorsum broadly arched, with ahnost equal slope toward each end, venter curved; overlap around entire mar- gin prominent except at anterior portion; antero-dorsal intersection slightly greater than 90°; postero-dorsal slope about 50°; posterior end short, sharp, slightly upturned ; surface granulose. Length, 1.17 mm; height, 0.53 mm; thickness, 0.43 mm. Golconda formation, locality 17, com- mon; Paint Creek formation, locality 18, common. Bairdia impendere Cooper, n. sp. Plate 2, figures 7-8 Carapace short and high with strong overlap around the entire margin, parti- cularly on the postero-dorsal portion; dor- sum strongly curved, venter almost straight ; hinge and articulation form broad curve in dorsal view; terminal projection somewhat long and very low, one-fourth the height of the shell above the venter; greatest height forward of center, greatest length just be- low center; postero-dorsal slope about 55°; surface smooth. Length, 1.23 mm; height, 0.80 mm; thickness, 0.50 mm. Renault formation, locality 14, rare. Bairdia insolens Cooper, n. sp. Plate 2, figures 1-2 Carapace elongate, dorsum curved, ven- ter straight ; antero-ventral margin meeting upper and lower margins at an angle ; over- lap prominent around entire margin, includ- ing hinge; posterior projection short and low; postero-dorsal slope about 55°; sur- face smooth. Length, 1.44 mm; height, 0.73 mm; thickness, 0.50 mm. Renault formation, locality 12, common. This form may be distinguished by its complete overlap and the unusual curvature of the anterior end. Bairdia sinuosa Cooper, n. sp. Plate 2, figures 11-12 Carapace ovate, tumid; left valve over- laps right except at apex of dorsum and at posterior ventral corner; in dorsal view hinge and overlap form smooth, sinuous curve; dorsum slightly curved, right valve projecting slightly above hinge; postero- dorsal slope about 50° ; ventral margin straight; anterior margin curved; greatest height at center, greatest length slightly above center; posterior projection short, located below center line; surface smooth. Length, 1.0 mm; height, 0.51 mm; thickness, 0.40 mm. Clore formation, locality 52, common; Kinkaid formation, locality 5, abundant. B. sinuosa might be confused with B. cestriensis Ulrich but it does not possess the depressed hinge line of the latter species. Bairdia cf . subelongata Jones and Kirkby Plate 2, figures 3-4 Bairdia subelongata Jones and Kirkby, 1879, Quart. Jour., Geol. Soc. London, vol. 35, p. 573, pi. 30, figs. 1-11, 16, Carboniferous of Great Britain. Carapace thin, rounded anteriorly, slender and tapering posteriorly; postero- dorsal slope low (ca. 35°), venter gently convex; overlap not conspicuous. Length, 1.30 mm; height, 0.52 mm; thickness, 0.40 mm. Golconda formation, locality 19, common. Bairdia subtila Cooper, n. sp. Plate 2, figures 5-6 Carapace wide, dorsum acutely arched, especially posteriorly; postero-dorsal slope 50°, venter concave and strongly overlap- ped ; Intersection of anterior and dorsal margins about 90 ° ; greatest height central ; greatest thickness In middle of posterior half ; posterior projection very poorly de- veloped. Length, 1.27 mm; height, 0.53 mm; thickness, 0.37 mm. Kinkaid formation, locality 3, abundant. This species is very similar to B. nasuta Morey, but differs In Its concave venter and lack of the symmetrical lens-like dorsal out- line. Genus Bairdiolites Croneis and Gale Bairdiolites brevirostris Cronels and Thurman Plate 2, figures 15-16 Bairdiolites brevirostris Croneis and Thurman, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 326, pi. 7, fig. 20, Kinkaid forma- tion. BARIDIIDAE 27 Carapace ovate; overlap around entire margin, especially prominent along antero- dorsal margin; postero-dorsal slope short and straight ; ventral margin straight in cen- tral portion; beak of medium length and located below median line; curved ridges low and close set, providing a broad area between the anterior rib and the end of the shell. Length, 0.77 mm; height, 0.43 mm; thickness, 0.33 mm. Menard formation, locality 7, common; Kinkaid formation, locality 5, abundant. Bairdiolites bulbosus Croneis and Bristol Plate 2, figures 19-20 Bairdiolites bulbosus Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 95, pi. 3, figs. 14-15, Menard formation. Bairdiolites emarginatus Croneis and Bristol, 1939, idem., p. 96, pi. 3, figs. 12, 13, Menard formation. Length, 0.80 mm; height, 0.47 mm; thickness, 0.31 mm. Golconda formation, locality 17, abun- dant; Glen Dean formation, locality 1, rare ; Vienna formation, locality 10, rare; Menard formation, locality 20, common; Clore formation, locality 26, common. Bairdiolites crassus Cooper, n. sp. Plate 2, figures 29-30 Carapace short and thick ; greatest height almost central; overlap prominent around entire margin, venter slightly curved, dor- sal margin rounded, anterior and posterior dorsal slopes fairly straight; postero-dorsal slope unusually steep (ca. 55°) ; anterior end rounded ; beak slightly below center line; greatest height central; curved ridges, if extended, would form a very short ellipse ; hinge depressed, postero-central ; articula- tion in dorsal view slightly curved. Length, 0.82 mm; height, 0.50 mm; thickness, 0.26 mm. Clore formation, locality 28, abundant. Bairdiolites fornicatus Cooper, n. sp. Plate 2, figures 27-28 Carapace small and very short; overlap prominent except on antero- and postero- ventral slopes; in lateral view articulation above extremities forms high arch or curve, which in most species is bounded by three nearly straight lines; beak and anterior ex- tremity very low; venter straight only in central third; dorsal articulation almost straight. Length, 0.75 mm; height, 0.47 mm; thickness, 0.29 mm. Menard formation, locality 15, common. This species may be distinguished by the arch-like margin above the extremities which occupy an extremely low position. Bairdiolites ovatus Croneis and Funkhouser Plate 2, figures 21-22 Bairdiolites o'uatus Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 357, pi. 9, figs. 13-14, Clore formation. Length, 0.73 mm; height, 0.46 mm; thickness, 0.35 mm. Kinkaid formation, locality 5. The holotype from the Clore formation has been so deeply corroded that the ribs have almost disappeared from both valves. This Kinkaid specimen, while slightly larg- er than the type, agrees closely in outline and general shape, the form ratio being identical. Bairdiolites procerus Cooper, n. sp. Plate 2, figures 39-40 Carapace ovate, rather high, with prom- inent overlap around entire margin ; antero- and postero-dorsal slopes straight, the latter about 60°; dorsal margin of left valve arched, that of right valve almost straight, so that upper margin is bounded by three almost straight lines ; lower margins curved ; beak short and low, less than one-fourth of height above venter ; curved ridges prom- inent and close-set and would, if extended to form a closed figure, result in a circle (in more elongate species the extended ridges would form ellipses) ; hinge de- pressed ; surface slightly pitted. Length, 0.80 mm; height, 0.49 mm; thickness, 0.35 mm. Kinkaid formation, locality 6, common. Bairdiolites tenuis Cooper, n. sp. Plate 2, figures 37-38 Carapace very long, somewhat thin, ends pointed; centro-dorsal area flat and sides almost parallel; each end tapers to a long, thin point; overlap greatest along venter, w^hich is almost straight, and prominent on the antero- and postero-dorsal slopes; the latter being about 40° from the horizontal; 28 CHESTER OSTRACODES OF ILLINOIS curved ridges, if extended would form flat or elongate ellipse ; hinge depressed and central; in dorsal view articulation forms almost symmetrical reverse or S curve, center of which is concave toward the right valve; beak long, almost on center line. Length, 0.91 mm; height, 0.35 mm; thickness, 0.28 mm. Renault formation, locality 13, common. Bairdiolites vulgaris Cooper, n. sp. Plate 2, figures 41-42 Carapace thick, overlap moderate around entire margin ; hinge depressed, postero- central; postero-dorsal slope steep (ca. 55°); venter straight in central portion swinging upward to meet beak and an- terior extremity ; antero-ventral curve forms angle at each extremity, ventral articulation swinging upward resulting in concave lower margin on right valve ; beak of average length, subcentral; greatest height central. Length, 0.84 mm; height, 0.48 mm; thickness, 0.35 mm. Paint Creek formation, locality 2, rare. B. vulgaris may be distinguished by the concavity of the ventral margin of the right valve. Genus Bythocypris Brady Bythocypris amsdenensis Morey Plate 2, figures 35-36 Bythocypris amsdenensis Morey. 1935, Jour. Pale- ontology, vol. 9, p. 481, pi. 54, figs. 2, 3, Ams- den formation. Carapace subovate ; dorsal margin arched, venter almost straight; overlap prominent except on posterior end; greatest thickness in posterior half, tapering anteriorly. Length, 0.48 mm; height, 0.29 mm; thickness, 0.23 mm. Clore formation, locality 26, rare; Fay- etteville shale, locality 31, abundant. Bythocypris clorensis Croneis and Funkhouser Plate 3, figures 1-2 Bythocypris clorensis Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 357, pi. 10, figs. 11, 12, Clore for- mation. Bythocypris ulli Coryell and Johnson, 1939. Jour. Paleontology, vol. 13, p. 222, pi. 26, figs. 13a, b, Clore formation. Length, 0.48 mm; height, 0.31 mm; thickness, 0.21 mm. Clore formation, locality 27, common ; Kinkaid formation, locality 6, rare. Bythocypris concava Cooper, n. sp. Plate 3 figures 3-6 Carapace elongate ovate, dorsum arched, venter concave, posterior slope straight, rising at high angle; overlap around entire margin, most prominent along anterior end and venter; hinge straight, surface smooth. Length, 0.46 mm; height, 0.23 mm; thickness, 0.18 mm. Vienna formation, locality 10, rare; Menard formation, locality 7, common; Kinkaid formation, locality 6, common. B. concava, characterized by the high angle of the postero-lateral slope and the concave venter is very close to B. cuneola Jones and Kirkby, 1886, which however, has a straight venter. Bythocypris fabalis Cooper, n. sp. Plate 3, figures 29-30 Carapace large, bean-shaped, tumid ; ends and dorsum rounded, venter almost straight (slightly concave) ; greatest height post- erior, greatest thickness well above middle; greatest length near venter ; middle overlap prominent; surface smooth. Length, 1.37 mm; height, 0.90 mm; thickness, 0.60 mm. Paint Creek formation, locality 23, depth 530-540 feet, common ; Golconda formation, locality 22, rare. Bythocypris gibba Cooper, n. sp. Plate 3, figures 7-8 Carapace somewhat rectangular, ventral extremities angular and produced into sharp, thin edges; posterior margin almost straight and nearly vertical ; dorsum broad- ly curved, venter distinctly concave, sub- parallel with dorsum; overlap prominent except on venter ; greatest height and thick- ness central, greatest length just above ven- ter; surface finely granulose to smooth. Length, 0.53 mm; height, 0.25 mm; thickness, 0.21 mm. Renault formation, locality 9, rare. Bythocypris modica Cooper, n. sp. Plate 3, figures 9-10 Carapace small, very ovate or subelllptl- cal ; ends and dorsum rounded, venter straight ; greatest height just back of middle ; BARIDIIDAE 29 greatest length and thickness central ; over- lap moderately developed, varies little around the entire margin. Length 0.42 mm; height, 0.23 mm; thickness, 0.18 mm. Paint Creek formation, locality 24, depth 2454 feet, common. Bythocypris opima Cooper, n. sp. Plate 3, figures 20-21 Carapace subovate, tumid; overlap indis- tinct, except on ventral margin, which is slightly concave ; greatest thickness slightly back of middle, greatest height above center ; posterior margin almost vertical, surface smooth. Length, 0.82 mm; height, 0.51 mm; thickness, 0.33 mm. Golconda formation locality 22, rare. Bythocypris ovata Cooper, n. sp. Plate 3, figures 11-13 Carapace small, bean-shaped, smooth ; ends and dorsum rounded ; greatest height slightly posterior ; greatest thickness central ; greatest length in lower half of shell ; over- lap prominent, especially along dorsum. Length, 0.69 mm; height, 0.44 mm; thickness, 0.31 mm. Paint Creek formation, locality 21, depth 1304-1323 feet, common. Bythocypris truncata Cooper, n. sp. Plate 3, figures 22-28 Carapace reniform ; dorsum highly arched and asymmetrical, posterior slope longer, venter straight to concave; ends rounded; greatest length well below center; greatest thickness almost central, surface sloping gradually in smooth convex curve to broad dorsum and posterior end, more rapidly to venter and anterior, giving distinctly acu- minate appearance to latter margins, over- lap left over right, most prominent along venter and adjacent parts of terminal mar- gins, surface smooth. Holotype, length, 0.98 mm; height, 0.65 mm; thickness, 0.50 mm. Renault formation, locality 25, common. Genus Cribroconch A Cooper, n. gen. Seminolites (?) (in part) Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 266. — Harlton, 1933, Jour. Paleontology, vol. 7, p. 27. Small ovate ostracodes with arched dor- sum, straight to slightly convex venter; overlap, right over left around entire margin except on postero-dorsal slope where artic- ulation is somewhat indented ; anterior end curved to acuminate ; posterior somewhat acuminate to rounded in lateral view ; post- ero-lateral slope bears transverse ridge or carina more or less perpendicular to long axis of shell which may be terminated above and below in short, sharp spines, directed backward ; postero-dorsal slope flattened ; surface marked by numerous irregularly spaced, relatively large, round pores. Genotype. — C. costata n. sp., Renault formation. Cribroconcha is flattened antero-dorsally like Healdia but the latter lacks the round perforations similar to those of Seminolites. Criboconcha lacks the anterior rib of Sem- inolites and has, instead of a curved posterior rib a straight, spine-terminated rib. Many species of Healdia carry the short spines at the ends of the posterior rib but all seem to lack the very definite perforations character- istic of Cribroconcha and Seminolites. Cribroconcha costata Cooper, n. sp. Plate 3, figures 37-42 Carapace small, ovate in lateral outline ; dorsum arched, venter straight; postero- dorsal slope low, hinge line incised ; postero- lateral slope interrupted by straight, vertical to slightly inclined rib terminated at each end by backward-directed spine; rib bor- dered by slight sinus; surface perforated by numerous round, deep pits, irregularly spaced ; antero-ventral angle sharp ; wedge- shaped in dorsal view; anterior end acum- inate, posterior margin irregular. Holotype, length, 0.50 mm; height, 0.30 mm ; thickness, 0.23 mm. Renault formation, locality 9, common ; Paint Creek formation, localties 24 and 28, common. This species differs from C. perforata (Harlton) and C. conspicua (Harlton) in having an arched rather than a smoothly convex dorsum, and in possessing a sharp antero-dorsal angle as compared to the rounded anterior end of the latter species. Harlton (1929, p. 266) states in his des- cription of the above species that a faint 30 CHESTER OSTRACODES OF ILLINOIS ridge bordered by a punctate sinus is located near the anterior end. None of the Chester specimens have even the faintest anterior ridge, but some do show an abrupt change in the curvature of the shell anteriorly, marked by a row of pits. If this is what Harlton designates as the anterior ridge, the two species referred to above belong in the genus Cribroconcha. In any event, the dev- elopment of the posterior end is so different from the typical Seminolites that these species should not be included in that genus. Cribronconcha conspicua (Harlton) Seminolites conspicuus Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 266, pi. 2, figs. 9a-c, Fayetteville shale. Cribroconcha fornicata Cooper, n. sp. Plate 3, figures 34-36 Carapace ovate in lateral outline, post- erior end round, dorsum arched, venter straight where prominent overlap (left over right) makes ventral margin of right valve slightly concave; anterior end truncates on ventral edge, placing greatest length well above center; greatest height central; post- erior end marked by narrow, slightly curved, vertical rib, concave inward, on the inner side of which is a narrow punctate sinus; overlap moderate along anterior end and venter, less so elsewhere; postero-dorsal slope flattened, with hinge incised. Length, 0.48 mm; height, 0.30 mm; thickness, 0.23 mm. Paint Creek formation, locality 24, common. Genus Healdia Roundy Healdia aequabilis Cooper, n. sp. Plate 3, figures 17-19 Carapace wide and thick, dorsum highly arched, with prominent posterior slope, venter broadly curved ; ends rounded ; post- erior ribs located well back from end of shell, straight and vertical, terminating in short knob; overlap moderate around en- tire margin except posterior dorsal slope, which is channelled ; greatest height central ; greatest thickness at posterior quarter, just in front of ribs. Length, 0.63 mm; height, 0.39 mm; thickness, 0.30 mm. Renault formation, locality 25, common ; Paint Creek formation, locality 2, common ; Golconda formation, locality 19, common. This form resembles H. simplex Roundy but lacks the abrupt posterior end and has a longer posterior dorsal slope, which is channelled from the apex of the dorsal arch. Healdia caneyensis Harlton Plate 3, figures 46-49 Healdia caneyensis Harlton, 1927, Jour. Paleon- tology, vol. 1, p. 208, pi. 33, figs. 2 a-c, upper Caney shale; 1929, Am. Jour. Sci., ser. 5, vol. 18, pp. 261, pi. 1, figs. 9 a-c, Springer shale; 1933, Jour. Paleontology, vol. 7, p. 26, pi. 7, fig. 10, Johns Valley shale. ? Brad- field, 1939, Bull. Am. Paleontology, vol. 22, no. 73, p. 105, pi. 8, fig. 14, Dornick Hills formation. Length, 0.57 mm; height, 0.35 mm; thickness," 0.27 mm. Glen Dean formation, locality 11, abundant. There seems to be considerable variation in the form described as H. caneyensis. The drawing of the dorsal view of the genotype is probably not representative, because the angularity shown is not characteristic of any known Healdia. However, the lateral view of this species shown later by Harlton (1929, pi. 1, fig. 9e) shows the typical dorsal outline. Healdia cornigera (Jones and Kirkby) Plate 3, figures 14-16 Cythere cornigera Jones and Kirkby, 1867, Ms., Geol. Soc. Glasgow, vol. 2, p. 223. Vine, 1884, Proc. Yorkshire Geol. Polyt. Soc, n.s., vol. 8, pp. 223, 239, pi. 12, figs. 9, 9a Car- boniferous of Great Britain, Bythocyprisf cornigera Jones and Kirkby, 1886, Ann. Mag. Nat. Hist., ser. 5, vol. 18, p. 251, pi. 6, figs. 8a-c, 9, Carboniferous of Great Britain. Healdia cornigera. Latham, 1932, Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, p. 38, fig. 23, Car- boniferous of Great Britain. IVaylandella cornigera. Bassler and Kellett, 1935, Geol. Soc. Am., Spec. Paper 1, p. 491. Length, 0.50 mm; height, 0.27 mm; thickness, 0.22 mm. Golconda formation, locality 19, rare. This species, referred to no less than four different genera, is returned to Healdia because of the work of Latham, who had access to many of Jones and Kirkby's col- lections and to topotype collections from their localities. Waylandella of Coryell and Billings lacks the postero-dorsal slope of Healdia, which the specimen figured by Jones and Kirkby (1886, pi. 6, fig. 8a) surely has. Latham's figure of this species BARIDIIDAE 31 also shows this slope. The Golconda form in addition to agreeing very closely with the British Carboniferous limestone specimen possesses a well-defined channel along the line of articulation on this slope. Healdia elliptica Cooper, n. sp. Plate 3, figures 43-45 Carapace elongate, subsymmetrical in out- line; anterior end rounded; venter slightly less convex than dorsum; antero- and postero-dorsal slopes almost equal ; posterior transverse ridge, located well back from end, vertical, slightly concave forward ; each end terminated by knob or short spine ; dor- sal outline lens-shaped; greatest thickness back of middle; overlap prominent along venter and anterior margin. Length, 0.58 mm; height, 0.33 mm; thickness, 0.25 mm. Golconda formation, locality 19, common. Healdia menisca Cooper, n. sp. Plate 4, figures 3-5 Carapace ovate, ends rounded, dorsum arched, venter almost straight; transverse rib, located fairly close to posterior end, strongly curved, merging into upper and lower margins in posterior quarter ; greatest thickness just in front of rib in center of posterior half; greatest height almost central; articulation channelled on the postero-dorsal slope and end; surface smooth; overlap moderate along venter and antero-dorsal slope, slight on anterior end. Length, 0.58 mm; height, 0.35 mm; thickness, 0.28 mm. Paint Creek formation, locality 24, depth 2454-56 feet, abundant. This species is characterized by the chan- nelled posterior and the lack of nodes or spines. A reversal of overlap of this species would produce a form similar to Cavellin- ella. H, menisca does not possess the postero- dorsal shoulder of Aurigerites. Healdia exilis Cooper, n. sp. Plate 3, figures 52-54 Carapace ovate, high and thin; dorsum arched, postero-dorsal slope somewhat flat- tened; low rib curved in wide arc, its ends merging with surface of shell near apex of arched dorsum, venter near posterior quart- er ; overlap prominent along venter, moder- ate on ends; greatest height central, greatest width through posterior quarter. Length, 0.60 mm; height 0.38 mm; thickness, 0.26 mm. Vienna formation, locality 10, abundant. Healdia cf. fayettevillensis Harlton Plate 3, figures 50-51 Healdia fayette'villensis Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 263, pi. 2, figs. 2a-c, Fayetteville shale. Length, 0.50 mm; height, 0.31 mm; thickness, 0.24 mm. Menard formation, locality 7, rare ; Clore formation, locality 4, common. The Clore specimens seem to be somewhat longer than the Fayetteville forms, although the two specimens illustrated by Harlton vary as much as 13 per cent in form ratio. The Chester form agrees very closely in general outline and in the development of the posterior end. Healdia minuta Cooper, n. sp. Plate 4, figures 6-7 Carapace small, short; ends rounded; dorsum slightly arched, venter convex; rib straight and inclined slightly backward ; postero-dorsal slope somewhat flattened ; overlap not pronounced; greatest height and thickness central. Length, 0.48 mm; height, 0.40 mm; thickness, 0.20 mm. Paint Creek formation, locality 24, common. Healdia mucronata Cooper, n. sp. Plate 4, figures 8-10 Carapace ovate, anterior end pointed, posterior bluntly rounded, dorsum and venter curved ; wedge-shaped in dorsal view; transverse ridge almost straight, ver- tical, close to posterior end. Ends of the ridges curve back to meet dorsal and ven- tral margins near the posterior quarter, giving postero-dorsal area triangular aspect ; articulation on postero-dorsal slope chan- nelled ; overlap not conspicuous. Length, 0.42 mm; height, 0.27 mm; thickness, 0.22 mm. Golconda formation, locality 19, rare. This species may be distinguished by its pointed anterior end and by the abrupt 32 CHESTER OSTRACODES OF ILLINOIS termination of the posterior end, particul- arly in the dosal view. Healdia ornata Morey Plate 4, figures 1-2 Healdia ornata Morey, 1935, Jour. Paleontology, vol. 9, p. 481, pi. 54, fig. 4, Amsden forma- tion. Healdia triangularis Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 290, pi. 6, fig. 22, Golconda formation. Length, 0.48 mm; height, 0.31 mm; thickness, 0.21 mm. Glen Dean formation, locality 11, common. The Amsden and Illinois specimens agree very closely in general outline, in the de- velopment of the sharp keel-like posterior transverse ridge which is perpendicular to the venter, and in the symmetry of the dorsal arch. Healdia ovoidea Cooper, n. sp. Plate 4, figures 15-17 Carapace ovate, dorsum and venter curved, ends rounded ; overlap conspicuous ; rib straight, inclined slightly backward and curving forward at ends to merge with shell near upper and lower margins; surface smooth. Length, 0.48 mm; height, 0.29 mm; thickness, 0.22 mm. Renault formation, locality 9, abundant ; Golconda formation, locality 19, common. Healdia radinula Cooper, n. sp. Plate 4, figures 18-20 Carapace elongate, anterior tapering to rounded end, dorsal and ventral margins broadly curved ; rib almost straight in central portion, curving broadly to meet dorsum and sharply to meet venter; over- lap moderate, surface smooth; greatest height and thickness postmedial. Length, 0.62 mm; height, 0.35 mm; thickness, 0.30 mm. Paint Creek formation, locality 24, common. H. radijiula is distinguished from H. menisca by the tapering of the anterior half of the carapace. Healdia tenuicosta Cooper, n. sp. Plate 4, figures 13-14 Carapace somewhat elongate, symmetri- cal; dorsum arched, venter slightly convex. ends equally rounded; rib thin, strongly curved, located well back from end ; postero- dorsal slope flat, articulation channelled ; overlap slight; greatest height central. Length, 0.51 mm; height, 0.28 mm; thickness, 0.23 mm. Vienna formation, locality 10, rare; Menard formation, locality 7, rare; Clore formation, locality 4, abundant; Kinkaid formation, locality 5, common. Healdia vinitaensis Harlton Plate 4, figures 11-12 Healdia ^vinitaensis Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 262, pi. 2, figs, la, b, Fay- etteville shale. Length, 0.60 mm ; height, 0.32 mm ; thickness, 0.22 mm. Vienna formation, locality 10, common. The Illinois and Oklahoma specimens are identical in form ratio and shape of outline. There may be some question about the agreement of the posterior ridges or nodes, due to the lack of clearness in the illustra- tion of Harlton's specimen. Genus Incisurella Cooper, n. gen. Carapace thick, subovate outline; dorsal margin arched, ventral margin slightly con- vex ; ends rounded ; overlap moderate around entire margin except on postero-dorsal slope, where the articulation is a narrow, slit-like channel and the slope of this portion of the shell resembles Healdia; subovate shallow area just in front of posterior margin im- pressed into the shell, interrupting but not changing its regular curvature ; overlap left over right. Genotype. — /. prima n. sp. This genus possesses many features of Healdia but differs in the development of the depressed area on the posterior end. Incisurella prima Cooper, n. sp. Plate 4, figures 27-29 Carapace thick subovate, ends rounded, dorsum arched, venter almost straight, but slightly convex; ventral margin of right valve somewhat concave; postero-dorsal slope short, articulation along hinge slit- like ; overlap moderate ; depression near posterior end flat, ovate slightly subcentral ; surface smooth, greatest thickness and height just back of center. BARIDIIDAE 33 Length 0.62 mm; height, 0.37 mm; thickness, 0,32 mm. Renault formation, locality 9, abundant; Paint Creek formation, locality 24. rare. /. prima may be distinguished from 7. lata n. sp. by its elongate anterior end, greater relative length, and somewhat smaller ovate posterior depression. Incisurella lata Cooper, n. sp. Plate 4, figures 21-22 Carapace short, subovate, thick, ends rounded ; ventral margin slightly convex ; posterior and anterior dorsal slopes almost equal, greatest height nearly central ; over- lap moderate on ends, greater on ventral margin ; ovate depressed area, shallow, sub- central, in center of curve around posterior quarter as seen in dorsal view ; depression bordered by low, very narrow rim ; surface smooth. Length, 0.60 mm; height, 0.37 mm; thickness, 0.28 mm. Renault formation, locality 25, rare; Paint Creek formation, locality 24, com- mon. Genus Microcheilinella Geis MiCROCHEILINELLA CORDATA Cooper, n. sp. Plate 4, figures 23-24 Carapace ovate, very thick, ends rounded, left valve overlaps right along venter and anterior end; posterior articulation depress- ed, producing decided heart-shaped outline in ventral view; hinge curved and slightly channeled ; dorsum arched ; venter straight ; greatest thickness posterior ; surface smooth. Length, 0.45 mm ; height, 0.22 mm ; thickness, 0.60 mm. Kinkaid formation, locality 3, rare. Microcheilinella? exilis Cooper, n. sp. Plate 4, figures 45-46 Carapace elongate, slender; ends round- ed, posterior slightly more acute; dorsum straight, venter slightly convex; greatest length about central; greatest height and thickness back of middle; dorsal area some- what flattened ; overlap around free margin inconspicuous; hinge straight, surface smooth. Length, 0.53 mm; height, 0.18 mm; thickness, 0.15 mm. Renault formation, locality 9, common. The generic affinities of this small slender form are somewhat obscure and it is being provisionally placed under Microcheilinella because of the flattened dorsal area and the slightly more acuminate posterior end. Microcheilinella obesa Cooper, n. sp. Plate 4, figures 35-38 Carapace ovate, thick; left valve larger and thicker than right ; prominent overlap around free margin; ends rounded, dorsum arched, venter straight; hinge curved, channeled ; greatest length central ; greatest height and thickness posterior ; surface smooth. Length, 0.58 mm; height, 0.30 mm; thickness, 0.37 mm. Paint Creek formation, locality 21, rare; Menard formation, locality 28, depth 838- 44 feet, rare ; Kinkaid formation, locality 28, rare. This species differs from M. cordata n. sp. in that it does not possess the indented posterior articulation which gives the latter species its heart-shaped outline. It also appears to be very close to M. subcorbuloides (Jones and Kirkby) and is about the same size as a form from the Barnett shale ten- tatively referred to the latter species by Roundy (1926, p. 8). Microcheilinella tumida Cooper, n. sp. Plate 4, figures 47-49 Carapace ovate, tumid ; ends rounded, posterior slightly more acute than anterior; venter straight; left valve larger, overlaps around entire free margins; hinge line depressed, sinuous; greatest length and height central ; greatest thickness posterior ; surface smooth. Length, 0.52 mm; height, 0.25 mm; thickness, 0.28 mm. Paint Creek formation, locality 2, rare; Golconda formation, locality 17, rare; Vienna formation, locality 36, rare; Kin- kaid formation, locality 3, rare. Genus Seminolites Coryell Seminolites ovalis Cooper, n, sp. Plate 4, figures 32-34 Carapace ovate, almost elliptical in lateral view, ends rounded, dorsum curved, venter slightly convex; overlap pronounced along posterior and ventral margms, slight along 34 CHESTER OSTRACODES OF ILLINOIS anterior and dorsum; posterior ridge thin, but quite high, directed backward along dorsal margin ; anterior ridge indistinct, little more than slight indentation and fold in regular curvature of shell ; hinge line sinuous; surface smooth. Length, 0.60 mm; height, 0.37 mm; thickness, 0.25 mm, Renault formation, locality 13, rare. Seminolites? reversus Cooper, n. sp. Plate 4, figures 41-42 Carapace subovate laterally, ends round- ed, posterior more acute, dorsum arched; overlap right over left around entire margin, most pronounced along dorsum and venter ; greatest height and length through center; greatest thickness posterior ; parenthesis-like ridges at each end, subparallel to margin ; anterior half higher than posterior. Length, 0.72 mm ; height, 0.47 mm ; thickness, 0.33 mm. Golconda formation, locality 17, rare. The lateral outline of this species is almost the exact reversal of S. compressus Coryell and, considering the thicker end to be posterior, the overlap is also reversed. There are other notable differences how^- ever which mark S. reversus as a new species, namely, the marked thickening of the over- lap near the mid-portions of the dorsal and ventral margins and the lack of large punctae. Seminolites symmetricus Cooper, n. sp. Plate 4, figures 53-55 Carapace subtriangular, tumid, ends rounded, dorsum arched, venter almost straight, but slightly convex; moderate overlap around entire margin except posterior slope of dorsum, w^hich is flattened much as in Healdia, articulation of this portion slightly channeled; posterior ridges thin, but prominent, subparallel to margin; anterior ridge short, low, and parallel to margin, inner side depressed Into slight furrow ; greatest length and height central ; surface smooth. Length, 0.55 mm; height, 0.33 mm; thickness, 0.27 mm. Paint Creek formation, locality 2, common. This species may be distinguished by Its symmetrical lateral outline, slight overlap, and the character of the posterior ridge. Genus Macrocypris Brady Macrocypris acuminata Cooper, n. sp. Plate 4, figures 30-31 Carapace elongate, ends rounded, dorsum arched, venter straight; overlap most prom- inent on posterior end, anterior narrow and tapering to well rounded point ; greatest thickness and height about middle of posterior half ; greatest length below middle ; surface smooth. Length, 0.72 mm; height, 0.41 mm; thickness, 0.33 mm. Menard formation, locality 30, rare. Macrocypris ovata Cooper, n. sp. Plate 4, figures 25-26 Carapace elongate, elliptical, ends rounded, dorsum arched, venter concave; greatest thickness near mid-length; overlap prominent along dorsum and venter only. Length, 1.18 mm; height, 0.53 mm; thickness, 0.36 mm. KInkaid formation, locality 3, common. Genus Tetratylus Cooper, n. gen. Carapace ovate, ends rounded, dorsum curved, venter straight to convex, end margins of some species bordered by low ridge, terminated above and below by round, knoblike spines of variable length ; valves highest anteriorly, with shallow sinus just back of center which is elongate verti- cally, extending from the dorsum down to about one-third of shell height, deepest near bottom ; right valve overlaps left around entire margin, but overlap Is inconspicuous except along venter; surface smooth to finely punctate. Genotype — T. elUpticus, n. sp., Paint Creek formation. Tetratylus differs from Seminolites In that the ridge, when present, is on and not back of the end margins of the shell, in the presence of four spines or knobs, and the presence of a sulcus; from Healdia In the presence of anterior spines and sulcus ; and from Cribrospira n. gen. in the presence of the anterior spines and ridge, the sulcus, and the lack of circular pits. The family classification of Tetratylus is somewhat uncertain because of the pri- mitlan sulcus and the cytherelloid outline. BEYRICHIIDAE 35 However, because of the simple hingement and the ovate outline with arched dorsum, it is believed to be most closely allied to the Bairdiidae. Tetratylus ellipticus Cooper, n. sp. Plate 5, figures 1-6 Carapace w^ith symmetrical lateral out- line, elliptical, greatest height and length central; dorsal outline somewhat wedge- shaped ; greatest thickness near posterior end ; terminal ridges fairly prominent ; spines short knob-like ; sulcus shallow just back of middle ; surface faintly punctate. Length, 0.58 mm; height, 0.33 mm; thickness, 0.23 mm. Paint Creek formation, locality 24, abundant. This species may be distinguished from T. menardensis (Croneis and Bristol) by its bilaterally symmetrical outline, and from T. elongatus n. sp. by the lower form ratio (length over height). Tetratylus elongatus Cooper, n. sp. Plate 5, figure 7 Carapace elongate, ends rounded and equal ; terminal ridges absent or very faint ; spines short, knob-shaped; sulcus shallow, almost central ; surface punctate. Length, 0.58 mm; height, 0.28 mm. Paint Creek formation, locality 24, rare. Tetratylus menardensis (Croneis and Bristol) Plate 5, figures 8-12 Healdia? menardensis Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 98, pi. 3, fig. 28, Menard formation. Length, 0.52 mm ; height, 0.28 mm ; thickness, 0.22 mm. Paint Creek formation, locality 24, common ; Menard formation, locality 28, depth 748 feet, common. There are apparently three fairly distinct Tetratylus species in the Illinois Chester : ( 1 ) The bilaterally symmetrical form, T. ellipticus; (2) the elongate T. elongatus, and (3) a short, asymmetrical form, T. menardensis. The latter differs from species of Healdia in possessing a sinus, four nodes, and a reversal of overlap. Family Beyrichiidae Ulrich Genus Beyrichia McCoy Beyrichia contracta Cooper, n. sp. Plate 5, figures 13-14 Carapace elongate, thin anteriorly in lateral view; dorsum thin, expanding to wide venter. Three nodes near dorsum, the middle one wider, but not so high as an- terior one; fold confined to border of ven- tral margin, separated from posterior node by a low saddle. Length, 0.65 mm; height, 0.37 mm; thickness, 0.35 mm. Golconda (basal Okaw) formation, lo- cality 18, rare. Differs from B. placida Croneis and Gale in the very narrow anterior end in the lateral view. Beyrichia sagitta Cooper, n. sp. Plate 5, figures 15-17 Carapace subrectangular, with distinct backward swing; free margins bordered by frilled false margin which is usually more or less completely broken away; three nodes, two located on either side of the center near the dorsum, the third at anterior end of dorsal fold which rises rapidly from posterior end, giving dorsal outline the shape of an arrow point ; dorsum thin, keel- like; venter wide. Length, 0.55 mm; height. 0.28 mm; thickness, 0.21 mm. Paint Creek formation, locality 2, rare. This species differs from B. placida Croneis and Gale in the extreme angularity of the dorsal outline. Family Cytherellidae Sars Genus Cavellina Coryell Cavellina bransoni (Morey) " Plate 5, figures 22-23 CytJierella bransoni Morey, 1935, Jour. Paleon- tology, vol. 9, p. 482, pi. 54, fig. 5, Amsden formation. Length, 0.75 mm; height, 0.50 mm; thickness, 0.31 mm. Kinkaid formation, locality 3, common. Following the ideas of Geis (1932) and Kellett ( 1935), this species is classified with the Carboniferous Cavellina rather than with the Mesozoic Cytherella. 36 CHESTER OSTRACODES OF ILLINOIS Cavellina congruens Cooper, n. sp. Plate 5, figures 20-21 Carapace elliptical, ends equally rounded ; dorsum slightly more curved than venter; overlap around entire margin, greatest along the venter, resulting in trough-like furrow in mid-portion; hinge straight; sides smoothly convex, greatest thickness just hack of middle ; greatest length and height central. Length, 1.10 mm; height, 0.51 mm; thickness, 0.35 mm. Clore formation, locality 4, abundant. This species is distinguished by its sym- metry and by the unusual overlap along the venter. Cavellina dispar Cooper, n. sp. Plate 5, figures 28-29 Carapace subelliptical ; dorsal margin slightly more arched than ventral ; ends asymmetrically rounded, making greatest length above middle ; overlap greatest around dorsal and posterior margins; hinge slightly sinuous; in dorsal view left valve appears much shorter than right because of offset at articulation ; greatest thickness near but somewhat back of middle ; greatest height central. Length, 0.82 mm; height, 0.49 mm; thickness, 0.31 mm. Menard formation, locality 20, common. C. dispar may be distinguished by its peculiar overlap, and by the differences in length of the two valves. Cavellina geisi (Croneis and Gale) Plate 5, figures 43-44 Cythcrella geisi Croneis and Gale, 1938, Denison Univ. Bull., Jour. Sci. Lab., vol. 33, p. 291, pi. 5, fig. 32, Golconda formation. Length, 0.93 mm; height, 0.58 mm; thickness, 0.38 mm. Vienna formation, locality 10, common. This Vienna Cavellina agrees closely with the figure and description of the Gol- conda form of Croneis and Gale. In addi- tion this specimen shows, in dorsal v'ltw, a somewhat sinuous hinge line and the in- ternal ridge in the posterior quarter is suggested by a faint interruption of the re- gular convexity of the valves at this point. Cavellina glandella (Whitfield) Plate 5, figures 49-50 Cytherellina glandella Whitfield, 1882, Am. Mus. Nat. Hist., Bull. 3, vol. 1, p. 54, pi. 9, figs. 28, 29, Spergen limestone. Hall, 1882, In- diana Dept. Geol. Nat. Res., 12th Ann. Rept, pi. 32, figs. 28, 29, Spergen limestone. Cummings and Beede, 1905, ibid., 30th Ann. Rept., pi. 26, figs. 28, 29, Spergen limestone. Cytherella glandella. Girty, 1915, U. S. Geol. Sur- vey, Bull. 593, p. 136, Batesville sandstone. Cavellina glandella. Geis, 1932, Jour. Paleon- tology, vol. 6, p. 186, pi. 26, figs. 9a-d, Salem limestone. Length, 1.0 mm; height, 0.60 mm; thickness, 0.29 mm. Kinkaid formation, locality 3, common. These Chester specimens, although smaller than those described from the Salem, appear to be identical in form ratio and other structural features. Cavellina exila Cooper, n. sp. Plate 5, figures 34-36 Carapace long, thin ; dorsal and ventral margins almost straight, subparallel ; over- lap moderate; anterior end uniformly rounded ; postero-ventral margin almost straight, posterior end not smoothly curved, greatest length above middle; greatest height and thickness posterior ; hinge sinu- ous, sharply curved in middle of anterior half, produced by pronounced overlap at this point. Length, 1.27 mm; height, 0.67 mm; thickness, 0.28 mm. Renault formation, locality 13, rare; Vienna formation, locality 10, common; Menard formation, locality 7, common; Clore formation, locality 26, common. Cavellina librata Cooper, n. sp. Plate 5, figures 37-38 Carapace subelliptical; dorsum rounded or broadly arched, venter straight ; overlap around entire margin, most pronounced on dorsum ; in dorsal view posterior end bound- ed by almost straight sides, giving somewhat pointed appearance ; anterior end sharply rounded ; hinge almost straight. Length, 0.78 mm; height, 0.45 mm; thickness, 0.29 mm. Clore formation, locality 4, common. Cavellina longula Cooper, n. sp. Plate 5, figures 41-42 Carapace elongate ; dorsum arched, vent- er almost straight ; left valve considerably BEYRICHIIDAE 37 smaller than right due to prominent over- lap ; posterior end asymmetrically rounded, due to flattening of curvature of postero- ventral portion of left valve ; greatest length above middle ; antero-ventral margin of left valve slightly upturned ; in dorsal view hinge line sinuous, offset at articula- tion prominent ; greatest thickness posterior ; greatest height central. Length, 0.98 mm ; height, 0.62 mm ; thickness, 0.42 mm. Golconda formation, locality 22, rare. Cavellina ovatiformis (Ulrich) Plate 5, figures 45-48 Cytherella ovatifortnis Ulrich, 1891, Jour. Cin- cinnati Soc. Nat. Hist., vol. 13, p. 209, pi. 17, figs. 3, 4a-c, Chester series. Batalina, 1924, Bull. Com. Geol., vol. 43, no. 10, pp. 1324, 1335, pi. 22, fig. 7, pi. 23, figs. 12-14, Lower Carboniferous of Russia. Cavellina mediocris Croneis and Thurman, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 327, pi. 7, fig. 17, Kinkaid formation. Cavellina oralis Croneis and Funkhouser, idem, p. 358, pi. 10, figs. 9, 10, Clore formation. Length, 1.03 mm; height, 0.69 mm; thickness, 0.49 mm. Paint Creek formation, locality 24, abundant; Vienna formation, locality 10, common ; Menard formation, locality 32, rare; Kinkaid formation, locality 5, com- mon; Fayetteville shale, locality 31, abundant. Cavellina parva Cooper, n. sp. Plate 5, figures 39-40 Carapace small, subelliptical, smooth ; overlap greatest on dorsum and venter; posterior end slightly less regularly curved than anterior ; greatest length slightly above center; greatest height slightly forward of center, greatest thickness back of center ; posterior end somewhat upturned ; hinge line sinuous, due to increase of overlap in anterior half. Length, 0.78 mm; height, 0.49 mm; thickness, 0.33 mm. Vienna formation, locality 10, common. The position of the greatest height, just forward of the middle, serves to distinguish this species which is somewhat intermediate between Cavellina and Paracavellina; how- ever, it does not possess the posterior ridge of the latter genus. Genus Paracavellina Cooper, n. gen. Carapace cytherelloid in outline; overlap right over left around entire margin ; dorsal and ventral margins arched to form greater overlap at these points; curvature of valves interrupted at each end by ridge close to and parallel with margins resulting in furrow just inside the ridge; surface smooth to granulose or minutely pitted. Genotype. — P. elliptica n. sp. This genus is distinguished from Cavel- lina by the ventral arch and terminal ridges ; from Birdsallella and Cavellinella by the presence of the anterior ridge and the loca- tion of the posterior ridge much closer to the margin. Paracavellina elliptica Cooper, n. sp. Plate 6, figures 5-6 Carapace elliptical, like Cavellina in out- line, greatest height and length central; overlap around entire margin ; regular convexity of right valve interrupted at each end by abrupt swelling, forming more or less prominent ridge parallel to terminal margins ; ridge extends farther around venter than around dorsum, matched on the left valve by a slight swelling that is much less noticeable on the right valve; width of left valve increased by regular increase in amount of overlap from each end toward center; greatest thickness in posterior quarter. Length, 1.06 mm; height, 0.67 mm; thickness, 0.48 mm. Golconda formation, locality 17, rare. Paracavellina opima Cooper, n. sp. Plate 6, figures 34-35 Carapace short, ovate, tumid ; terminal ridges somewhat prominent; ends broadly curved ; dorsum arched, venter almost straight; greatest overlap along venter; hinge straight ; greatest length and height central ; greatest thickness posterior ; sur- face smooth. Length, 0.68 mm ; height, 0.49 mm ; thickness, 0.33 mm. Paint Creek formation locality 24, rare. Paracavellina ovata Cooper, n. sp. Plate 6, figures 3-4 Carapace ovate; dorsum strongly arched, venter almost straight ; terminal ridges low, 38 CHESTER OSTRACODES OF ILLINOIS somewhat indistinct; greatest height and thickness just back of center, greatest length central ; hinge straight. Length, 0.76 mm; height, 0.55 mm; thickness, 0.38 mm. Menard formation, locality 15, rare. P. ovata resembles P. opima n. sp. from the Paint Creek, but is larger, not so abruptly terminated anteriorly, and has its greatest thickness more nearly central. Paracavellina pinguis Cooper, n. sp. Plate 6, figures 7-8 Carapace short, thick ; outline subellipti- cal in lateral view; ventral margin almost straight, dorsum arched ; anterior ridge more prominent than posterior; surface smooth. Length, 0.95 mm ; height, 0.62 mm ; thickness, 0.47 mm. Golconda formation, locality 17, common. P. pinguis may be distinguished from the genotype by the shorter, thicker carapace and by the relatively greater width across the anterior and posterior ends in lateral view. Paracavellina tumida Cooper, n. sp. Plate 6, figures 17-18 Carapace ovate, tumid ; right valve much thicker than left; greatest thickness poster- ior ; terminal ridges only slightly developed, posterior one quite indistinct ; hinge irregul- ar or sinuous; dorsum arched, venter less so; overlap greatest along venter; greatest thickness and height just back of middle, greatest length central ; surface smooth to pitted just inside terminal ridges. Length, 0.74 mm; height, 0.50 mm; thickness, 0.39 mm. Paint Creek formation, locality 24, common. Genus Platychilus Cooper, n. gen. Carapace cytherelloid in outline; ends rounded, overlap inconspicuous at these points ; dorsum and venter strongly arched, overlap very prominent ; valves regularly convex or with a broad shallow depression near mid-dorsal area; hingement cardine^ ; surface smooth. sThe ''tongue and groove" articulation at the hinge, common in so many ostracodes, is, unfortunately, often described as denticulation. Since the "tongue" does not possess the usual shape of a denticle or tooth, it is pro- posed to use the word "cardine" (L. cardinis, a pivot and socket on which the doors of the ancients revolved, or m building, a tenon and mortise) for this type of ostracode hingement. Genotype. — Platychilus ovoides n. sp., Vienna formation. Platychilus resembles Cavellina somewhat closely but may be readily distinguished from it by the unusual development of the overlap along the midportions of the dorsal and ventral margins, especially by the latter. It also lacks the post-ventral truncation common in Cavellina. Platychilus ovoides Cooper, n. sp. Plate 6, figures 26-27 Carapace cytherelloid in outline ; ends about equally rounded ; upper and lower margins of left valve slightly convex, sub- parallel ; right valve strongly convex, result- ing in very marked increase in overlap near mid-portion of the dorsum and venter ; over- lap greatest just back of middle on dorsum, just in front of middle on venter ; overlap on ends inconspicuous; greatest thickness just back of, and above center; both valves have pinched or broadly depressed area in front of point of greatest tumidity, greatest at dorsum, disappearing about mid-height; hinge straight, occupies anterior two-thirds of dorsal articulation ; surface smooth. Length, 0.63 mm; height, 0.43 mm; thickness, 0.26 mm. Vienna formation, locality 10, common. Genus Sargentina Coryell and Johnson Sargentina allani Coryell and Johnson Plate 6, figures 19-22 Sargentina allani Coryell and Johnson, 1939, Jour. Paleontology, voL 13, p. 223, pi. 25, figs. 9a-c, Clore formation. Sargentina forsetii Coryell and Johnson, idem. p. 224, pi. 25, figs. 10a, b, Clore formation. Male: length 0.91 mm; height, 0.61 mm ; thickness, 0.39 mm. Female: length, 0.95 mm; height, 0.62 mm; thickness, 0.49 mm. Clore formation, locality 27, common. These two species are similar in every respect except thickness. Because the greater thickness of the posterior portion of the shell has been considered a character that distinguishes female individuals, these two forms are believed to be the two sexes of the same species. The figured specimens are topotypes. figure 19 clearly showing the obesity of DREPANELLIDAE 39 the female as contrasted with the male (fig. 21), while the lateral views (figs. 20 and 22) are indistinguishable one from the other. Sargentina asulcata Cooper, n. sp. Plate 6, figures 1-2 Carapace subelliptical, tumid ; surface smooth; overlap prominent around entire margin; ends almost equally curved except for slight backward swing; greatest thick- ness slightly in front of middle, greatest length and height through center ; right valve has broad, somewhat flat area in postero-dorsal region, beginning just below hinge ; hinge line straight, meeting posterior margin at an angle with pronounced over- lap of right valve. Length, 0.89 mm; height, 0.62 mm; thickness, 0.45 mm. Kinkaid formation, locality 5, rare. S. asulcata differs from all other species in the lack of a prominent sulcus, in lieu of which is found the flattened area in the mid-dorsal portion of the left valve. Sargentina crassimarginata (Croneis and Thurman) Plate 6, figures 9-10 Sulcella crassimarginata Croneis and Thurman, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 328, pi. 7, figs. 15, 16, Kinkaid formation. Carapace subelliptical in lateral outline; right valve overlaps prominently around entire margin, especially along dorsum and venter ; dorsal margin of left valve straight, lateral outline with forward swing; sulcus deep, forward of center; hinge straight, notched at ends ; surface smooth. Length, 0.73 mm; height, 0.51 mm; thickness, 0.33 mm. Kinkaid formation, locality 5, rare. This form lacks the lateral configuration and type of overlap of Sulcella and also possesses a deeper sulcus than is present in the latter genus. Genus Sulcella Coryell and Sample Sulcella celsa Cooper, n. sp. Plate 6, figures 15-16 Carapace ovate, ends high and rounded, dorsum and venter curved ; sulcus and ter- minal ridges indistinct ; hinge line curved ; overlap greatest along dorsum and venter ; surface smooth. Length, 0.73 mm; height, 0.44 mm; thickness, 0.40 mm. Paint Creek formation, locality 24, depth 2454 feet, common. S. celsa is differentiated from S. ovata n. sp. by its low form ratio, 1.65 as compared to 1.8. Sulcella nodocosta Cooper, n. sp. Plate 6, figures 13-14 Carapace ovate, ends round ; dorsum curved, venter almost straight ; overlap mod- erate on dorsum and venter, inconspicuous on ends; sulcus very indistinct, wide, shal- low ; anterior ridge low, parallel to margin ; posterior ridge more prominent, higher at ends than in middle, giving somewhat knob- like appearance, especially in the dorsal view ; hinge slightly sinuous ; surface smooth. Length, 0.58 mm; height, 0.35 mm; thickness, 0.22 mm. Paint Creek formation, locality 24, depth 2454 feet, common. This species may be distinguished from S. ovata n. sp. by the raised and abruptly terminated posterior costae. Sulcella ovata Cooper, n. sp. Plate 6, figures 11-12 Carapace ovate; venter straight, dorsum curved ; ends rounded ; overlap most prom- inent on dorsum and venter ; sulcus central, wide, very shallow; terminal ridges quite inconspicuous; hinge line curved; greatest thickness in center of posterior half; sur- face smooth. Length, 0.72 mm; height, 0.42 mm; thickness, 0.29 mm. Paint Creek formation, locality 24, depth 2454 feet, common. Family Drepanellidae Swartz Genus CoRNiGELLA Warthin CORNIGELLA GOLCONDENSIS (Croneis and Gale) Plate 6, figures 36-37 Verrucosella golcondensis Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 275, pi. 5, fig. 8, Golconda formation. Croneis and Bristol, 1939, ibid., vol. 34, p. 85, pi. 4, fig. 6, Menard formation. Length, 0.67 mm; height, 0.36 mm; thickness, 0.27 mm. 40 CHESTER OSTRACODES OF ILLINOIS Paint dreek formation, locality 2, rare; Vienna formation, locality 10, rare; Men- ard formation, locality 28, common, Pennsylvanian species found in both Illi- nois and the mid-Continent area show that the genus Coriiigella is quite variable. The Chester species, illustrated here by an adult from the Paint Creek is known also from the Golconda, Vienna and Menard forma- tions. The mature specimen is almost indis- tinguishable from many elongate, short- spined species occurring abundantly in samples yielding many specimens of the Pennsylvanian C. minuta — C. longispina type. The only known differentiation is by means of the large form ratio (1.87) of the Chester series. Family Glyptopleuridae Girty Genus Glyptopleura Girty Glyptopleura alata Croneis and Funkhouser Plate 6, figures 45-47 Glyptopleura alata Cronies and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 349, pi. 10, fig. 3, Clore formation. Glyptopleura skathiae Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 217, pi. 25. fig. 4, Clore formation. Length, 0.95 mm; height, 0.59 mm; thickness, 0.40 mm. Clore formation, locality 26, common. This common Clore species is character- ized by its almost horizontal ribs and by its short ovate outline. Glyptopleura alvea Cooper, n. sp. Plate 6, figures 31-33 Carapace ovate, hinge long, straight ; dor- sum trough-like, very broad ; three fairly prominent ribs, central one traversing an elongate pit; less distinct ribs occur be- tween more prominent ones, one above and two below pit ; dorsal angles sharp. Length, 1.13 mm; height, 0.71 mm; thickness, 0.55 mm. Kinkaid formation, locality 5, rare. Glyptopleura Bristol: Croneis and Gutke Plate 6, figure 38 Glyptopleura bristoli Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 49, pi. 2, figs. 3, 4, Clore formation. Glyptopleura pergihha Croneis and Gutke, 1939, idem., p. 53, pi. 2, figs. 1, 2, Clore formation. Length, 0.96 mm; height, 0.55 mm. Renault formation, locality 25, rare; Paint Creek formation, locality 2, rare. Glyptopleura circumcostata Cooper, n. sp. Pate 7, figures 1-3 Carapace large, elongate, ends rounded; hinge straight ; posterior dorsal angle sharp ; hinge depressed, with notched overlap at each end ; ribs form triple U nested one inside the other, joined at the base; two additional unjoined ribs inside Inner U and below pit; cardinal area broad, shal- lowly V-shaped where hinge is slightly depressed. Length, 1.06 mm; height, 0.64 mm; thickness, 0.54 mm. Kinkaid formation, locality 3, common. Glyptopleura complexa Croneis and Bristol Plate 7, figure 32 Glyptopleura comlexa Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 87, pi. 4, fig. 25, Menard formation. Glyptopleura hamatilis Croneis and Bristol, 1939, idem., p. 88, pi. 4, fig. 22, Menard formation. Length, 0.71 mm; height, 0.42 mm. Vienna formation, locality 10, rare; Men- ard formation, locality 28, depth 746-49 feet, common ; Clore formation, locality 28, rare; Kinkaid formation, locality 5, rare. Glyptopleura elongata Cooper, n. sp. Plate 7, figure 42 Carapace long, about symmetrical in out- line, ends rounded, hinge straight, short compared to total length ; four ribs implant- ed in broad U, second from dorsum inter- rupted by pit; linear dimension greatly in- creased by comparative elongation of posterior end, observable by comparison w^ith the posterior dorsal angle; hinge only slightly more than half total length of shell. Length, 1.14 mm; height, 0.53 mm. Clore formation, locality 26, rare. Glyptopleura henbesti Croneis and Gutke Plate 7, figure 9-11 Glyptopleura henbesti Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 51, pi. 2, figs. 7, 8, Renault formation. Glyptopleura hendricksi Croneis and Gutke, 1939, idem., p. 52, pi. 2, figs. 5, 6, Renault forma- tion. GLYPTOPLEURIDAE 41 Length, 0.89 mm; height, 0.50 mm; thickness, 0.49 mm. Renault formation, locality 9, common. Glyptopleura inoptina Girty Plate 7, figures 20-22 Glyptopleura inoptina Girty, 1910, Ann. New York Acad. Sci., vol. 20, p. 236, Fayetteville shale. Roth, 1929, Pub. Wagner Free Inst. Sci., vol. 1, pp. 7, 35, 36. Coryell and Brockmier, 1931, Am. Midland Nat., vol. 12, p. 509. Carapace subquadrate ends rounded; dorsum straight, venter slightly convex; overlap very prominent around free margins; hinge slightly channeled, termin- ated posteriorly by well developed lip which overlaps margin; cardinal extremities an- gular, ventral extremities curved ; pit slight above and back of center ; costae prominent, regular, oblique; rib bends sharply upward around pit, coalescing with the rib next above rather than being broken by pit as in most other species. Length, 1.34 mm; height, 0.83 mm; thickness, 0.47 mm. Clore formation, locality 26, rare. This form, common in the Fayetteville shale and Pitkin limestone of Arkansas, is characteried by the union of the two ribs immediately above the pit. This form is thought to be identical with the form des- cribed but not figured by Girty (1910) from the Arkansas formation. G. costata (McCoy) also resembles this form in the rib arrangement but is shorter and lacks the rounded anterior margin of G, inoptina. Glyptopleura kellettae Croneis and Thurman Plate 7, figure 12 Glyptopleura kellettae Croneis and Thurman, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 319, pi. 7, fig. 8, Kinkaid formation. Length, 0.84 mm; height, 0.42 mm. Clore formation, locality 26, rare; Kin- kaid formation, locality 10, common. This specimen is somewhat less rounded on the posterior end than the holotype, but the rib pattern is similar. The original figure of the holotype shows an over ac- centuation of the ribs because of a heavy coat of ammonium chloride. Glyptopleura multicostata Morey Plate 7, figures 33-34 Glyptopleura multicostata Morey, 1935, Jour. Paleontology, vol. 9, p. 477, pi. 54, fig. 9, Amsden formation. Glyptopleura valkyriae Coryell and Johnson, 1939, Jour. Palentology, vol. 13, p. 218, pi. 25, fig. 6, Clore formation. Length, 1.05 mm; height, 0.67 mm; thickness, 0.44 mm. Clore formation, locality 27, rare. This Clore form, although a little higher than the one described by Morey, appears very close to that species, especially in the arrangement of the surface markings. Glyptopleura spinosa (Jones and Kirkby) Plate 7, figures 17-19 Kirkhya spinosa Jones and Kirkby, 1885, Ann. Mag. Nat. Hist., ser. 5, vol. 15, p. 185, pi. 3, fig. 12, Lower Carboniferous of Great Britain. Glyptopleura spinosa. Coryell and Brackmier, 1931, Am. Midland Nat. vol. 12, p. 513, pi. 2, fig. 10. Latham, 1932, Trans. Roy. Soc. Edinburgh, vol. 72, pt. 2, p. 732, fig. 20, Lower Carboniferous of Great Britain. Carapace small, short, retral swing prom- inent; ribs form single inclined loop or U across shell, upper side crossing deep elong- ate pit and terminating in antero-dorsal quarter in sharp elongate, spine-like node; surface reticulate; greatest thickness and height anterior ; overlap slight. Length, 0.48 mm; height, 0.29 mm; thickness, 0.25 mm. Menard formation, locality 20, rare. The lateral view of this form resembles G. parvacostata Geis, but lacks the promin- ent overlap of the Salem species. Glyptopleura symmetrica Croneis and Funkhoiiser Plate 8, figures 12-14 Glyptopleura symmetrica Croneis and Funk- houser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 353, pi. 10, fig. 1, Clore formation. Glyptopleura nertJiusae Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 217, pi. 25, figs. 5a, b, Clore formation. Length, 1.02 mm; height, 0.59 mm; thickness, 0.53 mm. Kinkaid formation, locality 5, common; Clore formation, locality 26, rare. 42 CHESTER OSTRACODES OF ILLINOIS Glyptopleura tyri (Coryell and Johnson) Plate 8, figures 10-11 Glypioplcuritcs tyri Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 219, pi. 26. figs. lOa-c, Clore formation. Length, 0.67 mm; height, 0.35 mm; thickness, 0.29 mm. Clore formation, locality 27, rare. Glyptopleura varians Croneis and Funkhouser Plate 8, figures 15-17 Glyptopleura varians Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 355, pi. 10, figs. 5, 6, Clore forma- tion. Glyptopleura freyjae Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 219, pi. 26, fig. 17, Clore formation. Ceratopleurina mimiri? Coryell and Johnson, 1939, idem., p. 221, pi. 26, figs. 9a, b, Clore formation. Length, 0.78 mm; height, 0.46 mm; thickness, 0.33 mm. Menard formation, locality 20, rare; Clore formation, locality 27, rare; Kinkaid formation, locality 3, common. Glyptopleura venosa (Ulrich) Plate 8, figures 19-21 Kirkhya 'uenosa Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist., vol. 13, p. 208, pi. 18, figs. 3a, b, Glen Dean formation. Glyptopleura venosa. Coryell and Brackmier, 1931, Am. Midland Nat., vol. 12, p. 516, pi. 2, fig. 5. Carapace ovate, nearly symmetrical, greatest height slightly in front of center ; hinge straight; ribs irregularly curved, anastomosing; surface reticulate; border of free margins flat to slightly depressed ; greatest thickness anterior. Length, 0.89 mm; height, 0.53 mm; thickness, 0.53 mm. Kinkaid formation, locality 3, common. This Kinkaid form is identical v^^ith that described by Ulrich from the Glen Dean of Kentucky in shape, markings, and size; the latter is erroneously stated in the original description, but Ulrich's figure shows that the holotype is almost exactly the same size as the Kinkaid specimen. Genus Glyptopleurina Coryell Glyptopleurina Coryell, 1928, Jour. Paleontology, vol. 2, p. 381. Idiomorphina Croneis and Gale, 1938, Bull, Deni- son Univ., Jour. Sci. Lab., vol. 33, p. 284. Coryell differentiated Glyptopleurina from other Glyptopleuridae by the presence of nodes and flange in addition to the inos- culating costae. The subsequent descriptions of several species from the Chester have shown that the flange is an extremely vari- able character, in some species being al- most inconspicuous around the entire free margin, and well developed only at the ends of the carapace. Idiomorphina was described as being more bulbous posteriorly than Glyptopleurina and as possessing a split anterior lobe. How- ever, in their description of G. bulbosa, Croneis and Gale list the split lobe as a specific character. The genotype /. insignia is a single right valve and since the marginal development of Glyptopleurina is somewhat variable, this feature therefore is of doubt ful generic value. It is suggested that the three described species of Idiomorphina are all females, which would explain the obe sity of the posterior end. Some species of Glyptopleurina bear a general resemblance to Geffenina and Geff- enites, except that the latter genera do not possess the curved rib joining the dorsal nodes, nor is the marginal lobe so sharply defined as in Glyptopleurina. The orienta- tion of this family has been reversed to con- form to more recent ideas concerning ostracode orientation, which makes the right valve the larger and the overlapping one. This puts the position of the greatest thick- ness and ventral truncation posterior, and the obtuse cardinal angle anterior (Geis, 1932, pp. 150-155). Glyptopleurina flexuosa Cooper, n. sp. Plate 8, figures 25-27 Carapace large, elongate, ovate, hinge straight, ends rounded; venter slightly convex, wedge-shaped in dorsal view; node slightly elongate vertically; ventral margin joined to narrow rib which turns abruptly upward and across shell where it joins an- terior inflation about midway between dorsum and venter; rib distinctly con- cave downw^ard ; hinge straight, channelled, with distinct notch at posterior end; mar- ginal ridge broad and close to ventral and posterior margins, merging into inflation on opposite end. GLYPTOPLEURIDAE 43 Length, 0.71 mm; height, 0.47 mm; thickness, 0.44 mm. Paint Creek formation, locality 2, rare. This species resembles G. bulbosa Croneis and Gale, but lacks the separation of the rib from the anterior lobe, and the decided curvature. The marginal ridge is also farther from the edge of the shell than in that species. Glyptopleurina iniqua Cooper, n. sp. Plate 8, figures 7-8 Carapace large, dorsum straight, venter broadly curved ; ends rounded, highest an- teriorly, posterior end thickest; node joined to posterior swelling by prominent rib which is concave downward ; marginal flange prominent only on anterior end ; surface reticulate; hinge straight. Length, 0.87 mm; height, 0.51 mm; thickness, 0.42 mm. Vienna formation, locality 10, common. This species is distinguished by the very unequal height of the two ends and by the extreme obesity of the posterior end. Glyptopleurina insculpta (Croneis and Funkhouser) Plate 8, figures 53-54 Jonesina insculpta Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 342, pi. 10, figs. 21, 22, Clore formation. Length, 0.88 mm; height, 0.53 mm; thickness, 0.42 mm. Clore formation, locality 26, rare; Kin- kaid formation, locality 5, common. The Kinkaid specimen is slightly more tumid than the holotype, but is in close agreement w4th the paratypes, which show the faint ridge subparallel to the antero- ventral portion of the free margin. Glyptopleurina insignis (Croneis and Gale) Idiomorphifia insignis Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 284, pi. 6, fig. 4, Golconda formation. Glyptopleurina longuronis Cooper, n. sp. Plate 8, figures 50-52 Carapace elongate; dorsum straight, venter broadly curved ; anterior node ovate, lower side joined to narrow rib which turns abruptly backward, ending in spine- like knob; marginal lobe marked with nar- row carina, curving up and around node; sinus small but deep ; ends rounded and greatly produced, making total length much greater than length of hinge; flat marginal flange prominent only on ends; hinge im- pressed into cardinal area as straight narrow groove ; portion of frill preserved anteriorly ; surface reticulate ; greatest thickness central. Length, 0.73 mm; height, 0.40 mm; thickness, 0.34 mm. Renault formation, locality 9, rare. This form, in contrast to G. bulbosa Croneis and Gale and G. flexuosa n. sp., is thickest in the central portion, suggesting that it is either a male or non-fertile female, and that the wedge-shaped forms with the greatest thickness quite close to the posterior end are fertile females. This difference is discernible only in the dorsal view. Glyptopleurina oehersi (Croneis and Bristol) Plate 8, figure 9 Idiomorphina oehersi Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 94, pi. 4, fig. 17, Menard formation. Length, 0.89 mm ; height, 0.48 mm. Golconda formation, locality 22, rare ; Vienna formation, locality 36, common ; Menard formation, locality 28, depth 746- 749 feet, common. Glyptopleurina ornata (Croneis and Gale) Plate 8, figures 35-37 Idiomorphina ornata Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 285, pi. 6, figs. 1, 2, Golconda formation. Length, 0.77 mm; height, 0.44 mm; thickness, 0.41 mm. Golconda formation, locality 19, rare; Glen Dean formation, locality 11, rare. Glyptopleurina simulatrix (Ulrich) Plate 8, figures 38-41 Beyrichia simulatrix Ulrich, 1891, Jour. Cincin- nati Soc. Nat. Hist., vol. 13, p. 205, pi. 18, figs. 7a, b, Chester series. Hollinella simulatrix. Bassler and Kellett, 1935, Geol. Soc. Am. Spec. Paper 1, p. 335. Carapace elongate, ovate ends rounded, hinge straight; nodes just below dorsum connected by curved, narrow rib-like ridge ; ridge bordered below and on posterior end by wider, hook-shaped ridge, broadest an- teriorly, gradually tapering and ending 44 CHESTER OSTRACODES OF ILLINOIS just back of posterior node; hinge depressed, notched at ends; surface reticulate. Length, 0.74 mm; height, 0.45 mm; thickness, 0.33 mm. Paint Creek formation, locality 2, rare; Golconda formation, locality 28, depth 1134-74 feet, rare. Glyptopleurina vetula Cooper, n. sp. Plate 8, figures 44-46 Carapace large, elongate, dorsum straight, ends curved, venter complex; re- tral swing fairly prominent ; medium sinus deep, anterior one shorter, more shallow; lobe connected to anterior inflation by low curved costa subparallel to another which curves around front of lobe; overlap prom- inent around free margins ; hinge channeled, overlapped at ends ; surface granulose ; frill, if ever present, completely broken away ; greatest thickness near anterior end ; greatest height through lobe. Length, 0.30 mm; height, 0.49 mm; thickness, 0.48 mm. Golconda formation, locality 19, rare. This species, like others from the Chester, lacks the posterior lobe possessed by many congeneric forms. It is probable that the great inflation of the posterior end has pre- cluded the development of this node, sug- gesting that these forms are females. Genus Mesoglypha Cooper, n. gen. Shell large, ovate in lateral outline, strongly convex, right valve much larger than left, overlapping along free margins, extending above dorsal margin ; surface sculpture centered about small but deep pit just in front of and slightly above center of shell, consists of rather indistinct, broad, subhorizontal costae covering about fifty per cent of shell surface; hinge line straight, slightly channeled, terminated at each end by flap overlapping the left valve; hinge- ment cardine, free margins frilled. Genotype. — AL mediocre n. sp.. Glen Dean formation. Mesoglypha is similar to Glyptopleura Girty but lacks the prominent ridges mark- ing the entire shell surface, is less quadrate in lateral outline. No species of Glypto- pleura are known to be frilled. Sargentina does not possess the same hinge structure, nor a pit (it has a sulcus) and it lacks the transverse costae. Mesoglypha mediocre Cooper, n. sp. Plate 8, figures 47-49 Carapace tumid, ovate in lateral outline, ends rounded ; dorsum and venter convex ; right valve much larger than left, overlap- ping around entire free margins, rising above hinge on dorsal margin ; postero-dorsal angle truncated ; forward swing moderate ; hinge straight, cardine, terminated at each end by large flap overlaping left valve at cardinal angles; surface smooth, except around pit, which area is marked by low, broad, somewhat indistinct subhorizontal costae ; pit just in front of center, quite deep although of small diameter ; greatest thick- ness in posterior quarter ; greatest height in anterior quarter; remnant of a frill appar- ently present at antero-ventral corner. Length, 0.93 mm; height, 0.59 mm; thickness, 0.49 mm. Glen Dean formation, locality 11, common. Genus Venula Cooper, n. gen. Glyptopleuridae with faint anastomosing costae, subquadrate outline, characteristic Glyptopleura hingement ; right valve larger, overlapping around free margin ; pit small, circular, almost midway between ends and slightly above midheight. Genotype. — Primitiopsisf striatus Cro- neis and Funkhouser. Venula has somew^hat the same outline as Primitiopsis (Jones) but lacks the reticulate surface, ventral swelling, the strong con- vexity, and the terminal flanges of the older genus. Venula striata (Croneis and Funkhouser) Plate 9, figures 26-27 Prunitiopsis? striatus Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 340, pi. 10, fig. 13, Clore formation. Carapace subquadrate, dorsum and ven- ter straight, parallel; anterior end rounded, posterior almost straight and vertical, giving forward swing; in dorsal view distinctly wedge-shaped, sides straight or very slightly convex ; hinge line straight, somewhat san- HOLLINELLIDAE 45 sabelloid with overlapping notch at each end, channeled in posterior half ; pit circular, slightly forward, above center; surface marked with numerous faint anastomosing or vein-like costae. Length, 0.72 mm; height, 0.39 mm; thickness, 0.29 mm. Kinkaid formation, locality 28, depth 628-33 feet, rare. This form does not possess the down- ward shell slope parallel to the posterior margin of the Clore specimen, although it seems to conform in most other respects. Family Graphiadactyllidae Kellett Genus Graphiadactyllis Roth Graphiadactyllis arkansana (Girty) Plate 9, figures 9-12 Kirkbya lindahli var. arkansana Girty, 1910, Ann. New York Acad. Sci., vol. 20, no. 3, pt. 2, p. 234, (no figs.), Fayetteville shale. Roundy, 1926, U. S. Geol. Survey, Prof. Paper 146, p. 7, figs. 15-16, Barnett shale. Graphiodactylus arkansanus. Kellett, 1936, Jour. Paleontology, vol. 10, pp. 773-775. Length, 1.31 mm; height, 0.70 mm; thickness, 0.60 mm. Fayetteville shale, locality 34, abundant. The genotype (figs. 10-12) shows the lack of the anterior spur, the short reticulae, the position of the pit just anterior to mid- length, and the development of a number of small spines on the anterior end. Figure 9, the interior of a right valve, shows the hinge line, the pitted muscle spot, and the arti- culation along the free margins. Graphiadactyllis tenuis Cooper, n. sp. Plate 9, figures 7-8 Bassleria fayettemllensis Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 256, pi. 1, figs. 2a-c, Fayetteville shale. Kirkbya lindahli var. arkansana (part). Roundy, 1926, U. S. Geol. Survey, Prof. Paper 146, p. 7, pi. 1, figs. 14a-c, Barnett shale. Carapace subrhomboid, narrowing (in lateral view) perceptibly toward posterior end ; dorsum straight, hinge slightly chan- nelled ; overlap most prominent around ends and venter; surface bears long straight to curved reticulae ; anterior spine-like pro- jection moderately developed ; a short and narrow but prominent posterior spine rises abruptly from antero-dorsal corner; pit or muscle scar just back of mid-length; great- est thickness posterior. Length, 1.12 mm; height, 0.63 mm; thickness, 0.50 mm. Fayetteville shale, locality 33, common. This species differs from the genotype G. arkansana (Girty) in having more elongate reticulae, a prominent posterior spine, and an anterior spur, and the pit located just behind, instead of in front of mid-length. Family Hollinellidae Swartz Genus Hollinella Coryell Hollinella granifera (Ulrich) Plate 9, figure 45 Bollia granifera Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist., vol. 13, p. 205, pi. 12, figs. 12a, b, Spergen limestone. Batalina, 1924, Com. Geol., Bull. 43,, no. 10, p. 1325, pi. 22, figs. 9-12, pi. 23, figs. 18-22. Hollina granifera. Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., vol. 35, p. 315, pi. 42, figs. 16, 17. Hollinella granifera. Bassler and Kellett, 1935, Geol. Soc. Am., Spec. Paper 1, p. 332. Length, 1.69 mm; height, 1.01 mm. Renault formation, locality 12, common. Two specimens from the Renault, although somewhat crushed, agree very closely with Ulrich's figures of the Kentucky Salem species. Little doubt is felt that they are the same because of the unusual features possessed by H. granifera. Hollinella longispina (Jones and Kirkby) Plate 9, figures 48-49 Beyrichia longispina Jones and Kirkby, 1886, Ann. Mag. Nat. Hist., ser. 5, vol. 18, p. 257, pi. 8, fig. 3, Carboniferous of Great Britain. Hollina longispina. Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., vol. 35, p. 316.— Latham, 1933, Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, p. 361, fig. 9, Carboniferous of Great Britain. Hollina steplianovi Batalina, 1924, Com. Geol., Leningrad, Bull. 43, p. 1335, pi. 23, figs. 23, 24. Length, 1.24 mm; height, 0.77 mm. Renault formation, localities 12 and 14, common. The Renault specimens agree with Jones and Kirkby's species in the presence of two large spines, one on the postero-ventral margin and the other almost exactly below the large node on the antero-ventral margin ; in the spinose free margins; in the retral swing of the valves, although in the British form this is somewhat more pronounced ; and in the lack of a frill or marginal flange. 46 CHESTER OSTRACODES OF ILLINOIS Although not mentioned in the description, the British form also seems to have an in- flated area between the nodes and the ven- ral margin as in the species shown here. The smaller node is poorly developed. It differs from H. grauifera (Ulrich) in the lack of the frill, the presence of a spinose margin with two very large spines, and in the distinct retral swing. HoLLiNELLA RADiATA (Jones and Kirkby) Plate 9, figures 42-44 Beyrichia radiata Jones and Kirkby, 1886, Ann. Mag. Nat. Hist., ser. 5, vol. 18, p. 257, pi. 8, figs. 1, 2a, b. Carboniferous of Great Britain. Beyrichia radiata cestriensis Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist., vol. 13, p. 204, pi. 14, figs. 4a, b. Hollina radiata cestriensis. Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., vol. 35, p. 315, pi. 42, figs. 19, 20. Hollina radiata. Latham, 1933, Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, pp. 359, 360, fig. 8. Hollina a'uonensis Latham, 1933, ibid., p. 360, fig. 9. Hollinella cestriensis. Bassler and Kellett, 1935, Geol. Soc. Am., Spec. Paper 1, p. 332. Hollinella radiata. Bassler and Kellett, 1935, ibid., p. 334. Hollinella typica Morey, 1935, Jour. Paleontology, vol. 9, p. 479, pi. 54, fig. 19, Amsden forma- tion. Hollinella sp., Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour, Sci. Lab., vol. 33, p. 341, pi. 9, fig. 15, Clore formation. Hollinella moreyi Croneis and Bristol, 1939, idem., vol. 34, p. 77, pi. 4, fig. 18, Menard formation. Carapace subrhomboidal, with moderate retral swing; ends rounded, cardinal angles obtuse ; hinge straight ; anterior node even with or below hinge line and more than twice diameter of posterior one ; sulcus deep, narrow, located between nodes just behind midpoint of shell ; surface coarsely punctate, sparsely to thickly spinose, margins and cardinal angles often carrying well-develop- ed somewhat larger spines; frill wide, flar- ing, occupying about three-fourths of free margin, often quite variable in width and m the angle of attachment to shell, some- times turning sharply outward, sometimes directed downward. Length, 1.34 mm; height, 0.78 mm. Glen Dean formation, locality 1, rare; Vienna formation, locality 10, common; Menard formation, locality 7, common ; Clore formation, locality 26, rare; Kinkaid formation, locality 5, common. The study of specimens from the Illinois Chester, ranging from the Glen Dean to the Kinkaid, and a close scrutiny of the pub- lished species from comparable horizons elsewhere, have convinced me that the vari- able character of the minor details makes it impossible to distinguish separate species from these formations. The position of the large node with reference to the dorsal margin, the variations in surface markings, and the changing character of the frill all appear to be quite variable. Family Kirkbyidae Ulrich and Bassler Genus Discoidella Croneis and Gale DiscoiDELLA AMPLA Cooper, n. sp. Plate 9, figures 36-37 Carapace very small, disc-shaped, outline subcircular, thickest in dorso-central area; very coarse reticulae in irregular rows sub- parallel to venter, becoming larger and more irregular in arrangement toward dor- sum ; cardinal area short, wide, somewhat depressed ; dorsal angles subequal. Length, 0.45 mm; height, 0.42 mm; thickness, 0.25 mm. Renault formation, locality 9, rare. D. ampla differs from other described species in the position of greatest thickness located near the dorsum, its larger size, and depressed cardinal area. ' Genus KiRKBYA Jones KiRKBYA ELONGATA Cooper, n. sp. Plate 10, figure 50 Carapace elongate, narrow, with promin- ent retral swing; hinge line straight in lat- eral view except for small offset at each end ; anterior shoulder prominent, posterior faint ; inner frill narrow, upturned ; greatest thickness well forward of and slightly above center; posterior cardinal angle 90°, an- terior angle acute ; surface markings not preserved. Length, 0.87 mm; height, 0.37 mm. Paint Creek formation, locality 2, rare. KiRKBYA HUMEROSA Coopcr, n. Sp. Plate 10, figures 47-49 Carapace thick, elongate, hinge straight, dorsal and lateral outlines asymmetrical; anterior shoulder prominent, extending slightly above hinge line; cardinal angles KIRKBYIDAE 47 acute, posterior greater; hinge line very slightly channelled ; second false keel up- turned or flaring, somewhat separated from first, flare making ends of valves strongly concave near the keel; upper-middle area strongly convex; reticulations polygonal, of average size; pit ovate, located well below center of shell. Length, 1.17 mm; height, 0.58 mm; thickness, 0.67 mm. Kinkaid formation, locality 3, common. K. humerosa may be distinguished from K. symmetrica Croneis and Thurman by the more prominent shoulder, asymmetrical outline, and by the more closely spaced false keels. KiRKBY cf. REFLEXA Girty Plate 10, figures 27-28 Kirkhya reflexa (not Ainphissites reflexus) Girty, 1910, Ann. New York Acad. Sci., vol. 20, p. 235, Fayetteville shale. Length, 1.13 mm; height, 0.53 mm; thickness, 0.46 mm. Golconda formation, locality 17, rare. Genus KiRKBYELLA Coryell and Booth KiRKBYELLA SULCATA Coopcr, n. Sp. Plate 10, figures 13-14 Carapace ovate, ends rounded ; dorsum slightly curved, venter slightly concave ; greatest height anterior; greatest thickness midway between dorsum and venter, back of median sulcus which is deepest ventrally ; ventral ridge terminated abruptly by verti- cal furrow crossing posterior end of shell near margin ; surface reticulae in sublongi- tudinal rows. Length, 0.43 mm; height, 0.25 mm; thickness, 0.20 mm. Paint Creek formation, locality 2, rare. Resembles K. truncata n. sp. in the pos- terior vertical furrow, but differs in the narrowing of the posterior end and the con- cave venter. KiRKBYELLA TRUNCATA Cooper, n. sp. Plate 10, figures 8-9 Carapace ovate in lateral view, anterior end rounded, posterior straight, vertical ; dorsum and venter slightly convex ; greatest thickness near venter; vertical sulcus-like trough crosses posterior end near margin re- sulting in pinched-in appearance in dorsal view; median sulcus shallow; surface reti- culae in subhorizontal rows, producing ir- regularly striated appearance. Length, 0.48 mm; height, 0.30 mm; thickness, 0.21 mm. Menard formation, locality 30, rare. This species differs from most Kirkbyella by the vertical trough near the posterior end, and from J^. sulcata n. sp. by its more quadrate outline. Genus Savagella Geis Savagella? acuminata Cooper, n. sp. Plate 11, figures 7-9 Carapace subrhomboidal in lateral view, ends rounded ; dorsum straight, venter slightly curved ; forward swing moderate ; dorsal outline strongly acuminate; hinge straight, slight narrow channel in posterior half, small notch at posterior end; pit small, shallow, circular, located just above and in front of center ; overlap right over left ; very indistinct around free margins ; surface marked by coarse reticulations, quite vari- able in size and shape ; greatest thickness in postero-ventral quarter; greatest height anterior. Length, 0.91 mm; height, 0.51 mm; thickness, 0.51 mm. Renault formation, locality 12, rare; Golconda formation, locality 18, rare; Vienna formation, locality 10, rare; Men- ard formation, locality 20, rare. The overlap of this species, although quite indistinct, is opposite to that given by Geis (1932, p. 168) for the Salem species. S. acuminata also resembles Kirkbyella Coryell and Booth in the position of greatest tumid- ity, but lacks the sulcus and the lobe border- ing the venter. The general lateral outline, surface markings and the pit favor the class- ification with Savagella. Subfamily Amphissitinae Cooper, n. subfam. The original description of Amphissites was emended and enlarged by Knight (1928) and by Roth (1929). The latter considers Amphissites a subgenus of Kirkhya while Knight, and Bassler and Kellett (1934) have followed the original author by giving it generic rank. Recent work on Carboniferous ostracode faunas, especially 48 CHESTER OSTRACODES OF ILLINOIS those from the Chester formations, has shown the need for finer discrimination among the forms hitherto grouped under this genus. The holotype A. rugosus Girty is char- acteristic of a group of species occurring in the Chester series and the Pennsylvanian and Permian systems. These species possess a single node or swelling, centrally located, and two or more carinae or false keels, par- allel or subparallel to the free margins of the carapace. A. centronotus Ulrich and Bassler is another good representative. Another group of species is intermediate between the genotypes of Arnphissites and Kirkbya. This group possesses one or more carinae and a prominent and characteristic kirkbyan pit but lacks the wing-like termin- ations of Kirkbydj as well as the central node, and the prominent kirkbyan shoulder. The surface reticulations are often coarser than those found on most species of Ajn- phissites. The third group which is especially char- acteristic of the Chester series and of many Pennsylvanian formations, possesses three nodes. Some species develop swellings in the antero- and postero-ventral corners, thus approaching a five-node form. The terminal nodes near the dorsal margin may be short and similar to the central node or, as is often the case, they may be elongated to form ridges which are subparallel to the anterior and posterior free margins. All three groups possess the typical kirk- byan characters, namely : the subcentral pit, straight hinge line, one or more carina or false keels, and a pronounced reticulated surface. It is proposed to restrict the name Amphissites to the forms characterized by the genotype A. rugosus and recognize the other two groups as genera for which the names Ectodemites and Polytylites are pro- posed. The subfamily Amphissitinae would include, in addition to these groups, the allied genera Knightina, Balantoides, and Ulrichia at least in part. There is some question concerning the actual occurrence of a sulcus between the two nodes of Ul- richia, and if one is not present, this genus should, ^ beyond question, belong to the Kirkbyidae and probably to the subfamily Amphissitinae. The several criteria for orientation of ostracodes have been variously interpreted for the Amphissitinae by different authors, so that considerable confusion is prevalent. In the original description of the genotype, Amphissites rugosus J Girty (1910) regarded the overlap as right over left. In this he was followed by Roundy (1926) who figured the genotype for the first time. Roth ( 1929) reversed this orientation, emphasizing the position of the teeth on the cardinal extrem- ities of what he considered the left valve. Roth was followed by Knight (1928), Kel- lett (1934), and others, but Bradfield (1935) and Payne (1937) reverted to the original orientation of Girty. Some authors have confused the issue by following one or the other of these methods and then incon- sistently orienting their figures. The original orientation of Girty has been followed be- cause this places the dorsal shoulder poster- ior, making the greatest height and width of the shell posterior. The swing of the valves, which is very slight if present in this group at all, is believed to be of little value in orienting these forms. Genus Amphissites Girty, restricted Cooper Amphissites, in part, of authors. Kirkbyidae with single, usually large node, located centrally or nearly so, be- tween anterior and posterior ends, com- monly slightly above line midway between dorsal and ventral margins; small elliptical pit located at postero-ventral edge of node ; valves subequal, right slightly overlapping left ; one or two false keels paralleling ven- tral margin but joining at cardinal extrem- ities; another carina, not completely encir- cling ventral node, joins a straight ridge parallel to hinge line ; short ridge joins inner carina at about 90°, giving cardinal area ap- pearance of narrow shield, with broadest end posterior (see pi. 9, figs. 1, 19, 34) ; surface reticulate. Amphissites carinatus Cooper, n. sp. Plate 9, figures 19-21 Amphissites centronotus? Croneis and Gale, 1938, Denison Univ., Jour. Sci. Lab., Bull. 33, p. 270, pi. 5, fig. 9, Golconda formation. Carapace short, thick and high, coarsely reticulate, marked by prominent carinae; node large, oval, slightly elongate horizon- tally, and lying just above center of shell KIRKBYIDAE 49 about midway between ends; second keel located well downward in lateral view appears almost to coincide with free margin ; narrow shield-like appearance produced by carina around cardinal area pronounced ; inner carinae parallel to middle one, ter- minate along line extending horizontally through pit; pit oval, directly beneath node but slightly flattened at top. Length, 0.93 mm ; height, 0.60 mm ; thickness, 0.61 mm. Golconda formation, locality 17, rare; Glen Dean formation, locality 11, abundant. A. carinatus on first examination appears to be identical with A. centronotus (Ulrich and Bassler), but the following differences may be noted : the form ratio of the Chester species is 1.5 while the average of the many published figures of A. centronotus is more than 1.7; the pit is more centrally located and much larger ; and the central keel is much closer to the free margins than in the younger species. The form described from the Golconda by Groneis and Gale is pro- bably a crushed specimen. parallel to the hinge line; reticulations of medium size, more or less without orderly arrangement. Length, 0. 69 mm; height, 0.40 m. Kinkaid formation, locality 3, common. Amphissites rugosus Girty Plate 9, figures 1-3 Amphissites rugosus Girty, 1910, Ann. New York Acad. Sci., vol. 20, p. 236, Fayetteville shale. Roundy, 1926, U. S. Geol. Survey, Prof. Paper 146, p. 7, pi. 1, figs, la-c, Barnett shale. Amphissites ivewveri Roth, 1929, Wagner Free Ins. Sci., vol. 1, pp. 9, 36, 39, pi. 2, figs. lla-c. Length, 0.80 mm; height, 0.46; thickness, 0.45 mm. Kinkaid formation, locality 3, rare. The Kinkaid specimen, although smaller than the holotype, has the same form ratio, 1.7. The arrangement and number of carina, and character of reticulations also correspond so that this form has been con- fidently identified with Girty's species. Amphissites exiguus Cooper, n. sp. Plate 9, figures 13-15 Carapace small, asymmetrical in lateral view, anterior end lowest; inner carina prominently developed as broad, smooth flange, not parallel to outer carina; node very small, central; pit small, almost indis- tinguishable ; anterior shoulder broad, not keel-like ; reticulations fine and irregularly arranged ; hinge line straight and depressed. Length, 0.50 mm; height, 0.30 mm; thickness, 0.29 mm. Kinkaid formation, locality 3, rare. This species is similar to A. carinatus n. sp. in dorsal area, but differs in possess- ing a higher inner carina, a much smaller central node, and a broad anterior shoulder as contrasted to the antero-dorsal carina of the latter species. Amphissites quadratus Cooper, n. sp. Plate 9, figure 4 Carapace elongate, somewhat rectangular, small round central node directly above deep oval pit ; outer carina smooth, pro- minent, parallel to free margin ; inner carina poorly developed at each end, subparallel to outer one; inner ridges faint, joining ridge Genus Ectodemites Cooper, n. gen. . Amphissites, in part, of authors. Kirkbyidae with regularly convex, or in- flated, ovate carapace, marked by one or more false keels but without well-defined nodes ; regularity of curvature often inter- rupted by slight swelling near central por- tion above pit. Genotype. — Ectodemites primus n. sp. This genus differs from Kni^htina in the absence of the prominent kirkbyan shoulder. The slight central swelling of Ectodemites should not be confused with the well defined central node of Amphissites and Polytylites. Ectodemites bicarinatus (Croneis and Thurman) Plate 9, figures 50-51 Ajnphissites bicarinatus Croneis and Thurman, 1938, Denison Univ. Bull., Jour. Sci. Lab., vol. 33, p. 311, pi. 7, figs. 10-12, Kinkaid formation. Length, 0.91 mm; height, 0.55 mm; thickness, 0.55 mm. Vienna formation, locality 10, common; Menard formation, locality 7, rare; Kinkaid formation, locality 28, depth 628-33 feet, common. 50 CHESTER OSTRACODES OF ILLINOIS ECTODEMITES COSTELLIFERUS (Croneis and Bristol) Plate 9, figure 22 Amphissites costellifera Croneis and Bristol, 1939, Denison Univ. Bull., Jour. Sci. Lab., vol. 34, p. 80, pi. 4, fig. 5, Menard formation. Amphissites decipiens Croneis and Bristol, 1939, idem., p. 81, pi. 4, fig. 4, Menard formation. Length, 1.0 mm; height, 0.55 mm. Golconda formation, locality 8, rare; Vienna formation, locality 10, rare; Men- ard formation, locality 28, rare. ECTODEMITES ELONGATUS Cooper, H. sp. Plate 9, figures 24-25 Carapace long, high, greatest thickness almost central ; anterior and central swell- ings joined by very low saddle, the former but slightly elevated above hinge line, end- ing at inner carina; pit well below center, elongated horizontally, deep; reticulations polygonal to ovate, regularly disposed with reference to carina; inner carina merges with line between two adjacent rows of reticulations about half way between pit and posterior end. Length, 0.79 mm; height, 0.47 mm; thickness, 0.42 mm. Kinkaid formation, locality 6, rare. ECTODEMITES MAGNIRETICULATUS Cooper, n. sp. Plate 9, figures 16-17 Carapace subrectangular ; dorsum straight, venter slightly concave, subparal- lel to dorsum, ends rounded ; retral swing slight ; surface very coarsely reticulate, smoothly convex, without nodes or should- ers; pit slightly below center, equidistant from ends; hinge straight, slightly de- pressed ; one very faint false keel closely parallels venter. Length, 0.74 mm; height, 0.38 mm; thickness, 0.31 mm. Paint Creek formation, locality 2, rare. ECTODEMITES cf. MONOMASTADIS (Coryell and Sohn) Plate 9, figure 35 Amphissites monomastadis Coryell and Sohn, 1938, Jour. Paleontology, vol. 12, p. 602, pi. 69, figs. 10a, b, Reynolds limestone. Length, 0.86 mm; height, 0.49 mm. Menard formation, locality 30, rare. EcTODEMiTES OBESUS (Croneis and Gale) Plate 9, figures 28-29 Amphissites ohesus Croneis and Gale, 1938, Deni- son Univ. Bull., Jour. Sci. Lab., vol. 33, p. 270, figs. 2, 3, Golconda formation. Length, 0,78 mm; height, 0.42 mm; thickness, 0.44 mm. Renault formation, locality 12, common ; Paint Creek formation, locality 2, rare; Golconda formation, locality 28, depth 1068-69 feet, rare. ECTODEMITES OBLONGUS (Jones and Kirkby) Plate 9, figure 23 Kirkhya ohlonga Jones and Kirkby, 1885, Ann. Mag. Nat. Hist., ser. 5, vol. 15, p. 181, pi. 3, figs. 6a, b. Carboniferous of Great Britain. Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist., vol. 13, p. 206. pi. 18, figs. 4, 5, Chester series. Amphissites ohlonga. Roth, 1929, Wagner Free Inst. Sci., Pub., vol. 1, p. 8. Length, 0.86 mm; height, 0.47 mm. Vienna formation, locality 10, common. ECTODEMITES PARVUS Coopcr, n. sp. Plate 9, figures 30-31 Carapace small, elongate, somewhat rectangular in lateral view, surface finely reticulate; false keels poorly developed, inner one almost indistinguishable; dorsal area considerably flattened, but rising posteriorly considerably above remainder of hinge line ; median and anterior swellings separated by fairly prominent saddle; pit oval, very distinct. Length, 0.71 mm; height, 0.28 mm; thickness, 0.32 mm, Menard formation, locality 7, common. This species closely approaches Am- phissites but lacks the carinal development of that genus, especially in the dorsal area. ECTODEMITES PLANUS Cooper, n. sp. Plate 9, figures 40-41 Carapace elongate, subrectangular in out- line, lenticular in dorsal view ; central swelling does not interrupt the regular line of curvature; carina indistinct; surface reticulae coarse and concentric ; anterior shoulder absent ; cardinal angles well round- ed ; pit located well below center, equidis- tant from the extermities of shell. KIRKBYIDAE 51 Length, 0.89 mm ; height, 0.46 mm ; thickness, 0.40 mm. Paint Creek formation, locality 24, rare ; Golconda formation, locality 8, common. EcTODEMiTES PRIMUS Cooper, n. sp. Plate 9, figures 46-47 Carapace large, elliptical in dorsal view, central and anterior swellings merged to form greatly inflated antero-dorsal quad- rant; enlarged portion begins just back of and above pit, continues upward to above hinge line and foward to inner carina; carinae somewhat low, smooth, diverging anteriorly; reticulations medium-sized, hexagonal for the most part, fairly regular especially between the carina. Length, 0.84 mm; height, 0.49 mm; thickness, 0.53 mm. Kinkaid formation, locality 5, common. ECTODEMITES QUADRATUS Cooper, n. sp. Plate 10, figures 11-12 Carapace tumid, quadrate in lateral out- line, dorsum and venter straight, parallel; ends rounded ; pit elongate, almost hori- zontal, subcentral ; keels low, indistinct, inner one only being continuous around entire free margin ; posterior end truncate ; surface irregularly marked with polygonal reticulations, irregular in size and shape, smallest in center, becoming larger and more irregular in shape toward ends and venter ; greatest length and thickness central. Length, 0.80 mm ; height, 0.46 mm ; thickness, 0.49 mm. Paint Creek formation, locality 21, depth 1304-43 feet, rare. E. quadradus may be distinguished from E. planus n. sp. by its irregular reticulate pattern, greater thickness, and lower form ratio. EcTODEMiTES TUMiDUS Cooper, n. sp. Plate 10, figures 1-3 Carapace short, thick, widest on anterior end due to prominence of well-developed shoulder; central swelling rising gradually from cardinal area, ending abruptly just above median pit; outer carina parallel to II free margin, inner one becoming more widely separated from first toward anterior i end ; reticulations subcircular to polygonal. Length, 0.60 mm; height, 0.33 mm; thickness, 0.37 mm. Clore formation, locality 26, common; Kinkaid formation, locality 3, rare. This species somewhat resembles Am- phissites due to the prominence of the cen- tral swelling; however, this feature is not well defined except on the ventral side near the pit. EcTODEMiTES WAREi (Morey) Plate 10, figure 22 Amphissites ivarei Morey, 1935, Jour, Paleontol- ogy, vol. 9, p. 477, pi. 54, fig. 7, Amsden formation. Length, 0.63 mm; height, 0.38 mm. Clore formation, locality 26, common; Kinkaid formation, locality 5, common. Genus Polytylites Cooper, n. gen. Amphissites, In part, of authors. Mauryella Harlton, 1929, Am. Jour. Sci., sen 5, vol. 18, p. 257, pi. 1, fig. 5. Kirkbyidae with small to large, circular to ovate central node, with low to pro- minent, short to elongate shoulders or swellings in dorsal extermities. When the latter are short and prominent the carapace has a trinodal appearance. A few species have swellings at the ventral extremities, producing a form with a five-noded ap- pearance, as in Polytylites quincollinus ( Harlton) . Surface marked by kirkbyan pit below central node and fine to coarse re- ticulations; one to two carina more or less parallel to free margin. Genotype. — Polytylites geniculatus n. sp. Polytylites ambitus Cooper, n. sp. Plate 10, figure 46 Carapace large, subrectangular, with very prominent flange-like inner carina, outer one poorly or not at all developed ; central node large, circular, well above and behind center of shell ; anterior shoulder large, pro- jecting well above hinge, located some dis- tance from anterior margin ; pit large, deep, situated on antero-ventral margin of cen- tral node ; surface finely reticulate. Length, 0.89 mm ; height, 0.53 mm. Renault formation, locality 12, rare. 52 CHESTER OSTRACODES OF ILLINOIS This species may be distinguished by the subcentral position of the central node, the upper margin of which almost reaches the hinge line, and the unusually large flat area developed in front of the anterior shoulder. POLYTYLITES BIFORATUS (Croneis and Thurman) Plate 10, figure 23 Amphissites hiforatus Croneis and Thurman, 1938, Denison Univ. Bull., Jour. Sci. Lab., vol. 33, p. 312, pi. 8, figure 9, Kinkaid for- mation. Length, 0.87 mm ; height, 0.46 mm. Golconda formation, locality 8, common. POLYTYLITES BRADFIELDI (Croneis and Funkhouser) Plate 10, figures 24-26 Amphissites hradfieldi (not A. rothi) Croneis and Funkhouser, 1938, Bull. Denison Univ.. Jour. Sci. Lab., vol. 33, p. 346, pi. 10, fig. 15, Clore formation. Amphissites lineatus Croneis and Bristol, 1939, idem. vol. 34, p. 83, pi. 4, figs. 1, 2, Menard formation. Length, 1.0 mm; height, 0.58 mm; thickness, 0.55 mm. Renault formation, locality 9, common ; Vienna formation, locality 10, abundant; Menard formation, locality 30, common ; Clore formation, locality 4, abundant ; Kin- kaid formation, locality 5, common. POLYTYLITES CONCAVUS (Croneis and Bristol) Amphissites conca'vus Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 79, pi. 4, figs. 8, 9, Menard formation. POLYTYLITES CRASSus Cooper, n. sp. Plate 10, figures 15-17 Carapace small, but very thick, highest on posterior end ; central node prominent ; anterior shoulder high, but of smaller diameter than the node; posterior swelling absent; pit small and indistinct; inner keel distinct, parallel to outer one only in postero-ventral region ; reticulations fine. Length, 0.40 mm;, height, 0.24 mm; thickness, 0.27 mm. Kinkaid formation, locality 3, common. POLYTYLITES DIRECTUS Cooper, n. sp. Plate 10, figure 43 Carapace flat, with three nodes and pro- minent inner keel rising abruptly from surface ; anterior and central nodes dis- tinctly elongate vertically posterior node al- most circular ; inner keel unusually high, parallel to free margin, except at posterior extremity; inner side marked by single row of pits elongated radially; in dorsal view space between the two carinae occupied by at least five rows of reticulae; pit small, subcircular, slightly forward of ventral end of central node. Length, 0.98 mm ; height, 0.53 mm. Glen Dean formation, locality 1, rare. POLYTYLITES DIVERSUS Cooper, n. sp. Plate 10, figure 4 Carapace small, thicker but much lower on anterior end ; greatest height through posterior end of hinge ; anterior shoulder and central node poorly developed; pit slightly forward of and below center of shell ; surface marked by comparatively coarse re- ticulations; inner keel parallel to outer one along ventral margin only, diverging at either end. Length, 0.43 mm ; height, 0.27 mm. Vienna formation, locality 10, rare. POLYTYLITES ELONGATUS (Croneis and Bristol) Plate 10, figure 44 Amphissites elongatus Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci, Lab., vol. 34, p. 81, pi. 4, fig. 10, Menard formation. Length, 0.97 mm; height, 0.56 mm, Kinkaid formation, locality 5, common, POLYTYLITES FOSSILIS (Croneis and Thurman) Plate 10, figures 51-52 Arnphissites fossilis Croneis and Thurman, 1938, Denison Univ. Bull., Jour. Sci. Lab., vol. 33, p. 312, pi. 8, fig. 18, Kinkaid formation. Length, 0.85 mm; height, 0.47 mm. Renault formation, locality 9, common; Paint Creek formation, locality 2, rare; Golconda formation, locality 8, common. POLYTYLITES GENICULATUS Cooper, n. sp. Plate 10, figures 34-37 Carapace small, somewhat rectangular in outline, with inner sharp, well-defined carina marking broad curve nowhere paral- lel to outer one ; small, round node rises abruptly (and is relatively high) from shell surface, a little above and behind cen- KIRKBYIDAE 53 ter, placing kirkbyan pit exactly at its antero-ventral edge; anterior shoulder rises well above hinge line, somewhat larger than central node ; posterior node much smaller, barely rises above the hinge ; reticulations fairly coarse especially near keels; several short, thin spine-like protuberances also mark surface. Length, 0.68 mm ; height, 0.40 mm ; thickness, 0.38 mm. Renault formation, locality 9, common; Vienna formation, locality 10, abundant. PoLYTYLiTES GROVEi (Croneis and Gutke) Amphtssites gro'vei Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, pi. 2, figs. 28, 29, Renault formation. POLYTYLITES? NODOBLIQUUS (Croneis and Gale) Plate 10, figures 38-41 Knightina nodobliqua Croneis and Gale, 1938, Bull, Denison Univ., Jour. Sci. Lab., vol. 33, p. 274, pi. 5, fig. 1, Golconda formation. Carapace large, rectangular, with large oval central node elongated along line ris- ing a little toward anterior end ; terminal swellings not sharply defined, rise gradually to form regular ridges sharply curved posteriorly to parallel the single very faint carina; carina not keel-like, but broad and rounded, forming a broad, flat area along ventral margin ; anterior shoulder elevated but little above hinge line and gradually dies out on a line slightly below pit ; reticulations fine to coarse, elongate on the carina. Length, 0.97 mm ; height, 0.50 mm ; thickness, 0.58 mm. Renault formation, locality 12, rare; Paint Creek formation, locality 24, rare; Golconda formation, locality 8, common; Vienna formation, locality 10, common. POLYTYLITES QUINCOLLINUS (Harlton) Plate 10, figure 45 Maury ella quincollina Harlton, 1929, Am. Jour. Sci., ser. 5, vol., 18, p. 257, pi. 1, fig. 5, Fayetteville shale. Carapace large, rectangular in outline ; coarse surface reticulations interrupted by five nodes or swellings; central and antero- dorsal nodes rise abruptly, others are lower and rise gradually above surface; reticula- tions apparently without orderly arrange- ment and occur without interruptions over all protuberances ; inner keel almost ob- literated by ventral nodes which form pro- minent saddle just below central node; pit deep, elliptical, with long axis 45° to hori- zontal, rising toward anterior end. Length, 0.91 mm; height, 0.51 mm. Renault formation, locality 9, rare. This species, because of its five swellings, large size, and coarse reticulations has been identified as P. quincollinus (Harlton). Comparative material from the lower Fayetteville shows some variation in size and extent of the ventral swellings. Some forms also axhibit a more orderly arrange- ment of reticulations than does the specimen from the Renault. POLYTYLITES RETICULATUS Cooper, n. sp. Plate 10, figure 10 Carapace coarsely reticulate, especially in area between two false keels ; first carina parallel to free margin; central node rela- tively small, almost round, with kirkbyan pit at antero-ventral edge ; inner carina sub- parallel somewhat widely separated from outer one by four rows of very large, oval to subangular reticulations ; anterior node well developed, larger than central node, projecting well above hinge line; posterior node small, inclined slightly forward from vertical, projecting slightly above hinge line. Length, 1.06 mm; height, 0.60 mm. Clore formation, locality 4, abudant. POLYTYLITES siMiLis (Croneis and Gale) Amphtssites similis Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 269, pi. 5, fig. 6, Golconda formation. POLYTYLITES SUBLINEATUS (Croneis and Thurman) Plate 11, figure 24 Amphissites suhlineatus Croneis and Thurman, 1938, Bull. Denison Univ., Jour, Sci. Lab., vol. 33, p. 315, pi. 8, fig. 16, Kinkaid forma- tion. Length, 1.05 mm; height, 0.67 mm. Kinkaid formation, locality 5, common. POLYTYLITES SUPERUS (Croneis and Gale) Plate 11, figures 6, 17 Amphissites siiperus Croneis and Gale, 1938, Den- ison Univ. Bull., Jour. Sci. Lab,, vol. 33, p, 272, pi. 5, figs, 13, 14, Golconda formation. 54 CHESTER OSTRACODES OF ILLINOIS Length, 0.89 mm ; height, 0.55 mm. Golconda formation, locality 16, com- mon; Glen Dean formation, locality 1, rare; Menard formation, locality 7, com- mon. POLYTYLITES TRICOLLINUjS (Jones and Kirkby) Plate 11, figures 1-4 Kirkhya tricollina Jones and Kirkby, 1886, Ann. Mag. Nat. Hist., sen 5, vol. 18, p. 261, pi. 8, fig. 19, Carboniferous of England. Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist, vol. 13, p. 207, pi. 18, figs. 8a, b, Chester series. AmpJtissites tricollina. Roth, 1929, Wagner Free Inst. Sci. Pub., vol. 1, p. 3. Bassler and Kellett, 1935, Geol. Soc. Am., Spec. Paper 1, p. 155. Length, 0.78 mm; height, 0.45 mm; thickness, 0.40 mm. Glen Dean formation, locality 1, rare. PoLYTYLiTES TRiLOBUS (Croneis and Gale) Plate 11, figure 5 Amp/iissites trilohus Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 271, pi. 5, fig. 5, Golconda formation. Length, 1.0 mm; height, 0.55 mm. Golconda formation, locality 16, rare. PoLYTYLiTES wiLSONi (Croneis andGutke) Plate 11, figures 22-23 Ampliissites ivilsoni Croneis and Gutke, 1939, Denison Univ. Bull., Jour. Sci. Lab., vol. 34, p. 47, pi. 2, figs. 24, 25, Renault formation. Length, 0.78 mm; height, 0.44 mm; thickness, 0.40 mm. Renault formation, locality 9, common. Family Kloedenellidae Ulrich and Bassler Genus Chesterella Croneis and Gutke Chesterella? incerta Cooper, n. sp. Plate 11, figures 28-30 Carapace subrectangular ; hinge straight, with small tooth at posterior end fitting into corresponding process on right valve ; valves almost equal in size with little or no ap- parent overlap, greatest thickness and least height anterior ; greatest length almost cen- tral or slightly above; ventral lobe rises gradually from posterior, narrowing and terminating abruptly just beneath node in antero-dorsal quarter; posterior node just back of center. Length, 0.55 mm; height, 0.30 mm,- thickness, 0.30 mm. Renault formation, locality 25, common. The orientation of this genus is re- versed from that given by Croneis and Gale because of the backward swing of the valves in lateral view, and by reference to the fam- ily description, the hinge process is located posteriorly. The generic designation of C. incerta and C. fissurata Croneis and Gale have been questioned due to the great similarity of these forms to Jonesina. This is not true for C. exuta Croneis and Gale, which appears to possess characters quite different from those of any other described genus. C. incerta is distinguished from C. fissurata by the narrower anterior end in lateral view. Genus Deloia Croneis and Thurman Deloia spinosa Croneis and Bristol Plate 11, figure 18 Deloia spinosa Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 73, pi. 3, fig. 21, Menard formation. Leightonella torta Croneis and Gale, 1938, idem., vol. 33, p. 263, pi. 5, fig. 19, Golconda for- mation. Length, 0.95 mm; height, 0.51 mm. Renault formation, locality 9, rare ; Glen Dean formation?, locality 1, rare; Vienna formation, locality 10, rare; Menard for- mation, locality 7, rare; Kinkaid formation, locality 3, rare. Deloia tumida Cooper, n. sp. Plate 11, figures 13-14 Carapace ovate, hinge straight ; posterior end rounded, anterior margin meets dorsum in obtuse angle ; valves flat, except at posterior end, where postero-dorsal quarter is abruptly inflated ; free margin coarsely fringed. Length, 0.75 mm; height, 0.44 mm; thickness, 0.29 mm. Kinkaid formation, locality 3, rare. The flatness of the valves is probably ac- centuated by some crushing, but it is be- lieved that the abrupt swelling would still be very prominent in an uninjured specimen. Genus Denisonia Croneis and Bristol Denisonia brevicosta Cooper, n. sp. Plate 11, figures 40-41 Carapace elongate, with slight backward swing, ends rounded ; dorsum straight. KLOEDENELLIDAE 55 A^enter curved ; anterior end thickest but nar- rower than posterior; sulcus postcentral, traversed by short, thin rib or carina in- clined toward venter, anteriorly merging with thickening of valve at this point, terminating abruptly just back of sulcus; valves irregularly inflated anteriorly, less so between sulcus and venter, producing shal- low saddle-like area in antero-ventral quar- ter; edges near free margins abruptly up- turned in false keel or basal portion of frill, which has been broken completely from this specimen. Length, 0.82 mm; height, 0.46 mm; thickness, 0.31 mm. Golconda formation, locality 22, rare. Denisonia cirrata Cooper, n. sp. Plate 11, figure 34 Carapace elongate, posterior swing pro- nounced ; dorsal line straight, ends rounded, venter curved ; greatest height postcentral ; valve uniformly inflated around deep sulcus located postdorsally of center ; sulcus tra- versed by short, triangular platform-like rib rising almost perpendicular from surface; rib widest anteriorly, merging with surface of shell behind sulcus ; hingement cardine ; frill composed of elongate, needle-like spines in row which parallels free margins. Length, 0.71 mm; height, 0.38 mm. Golconda formation, locality 18, rare. This species is distinguished by its pro- minent backward swing and by its short and unusually wide carina. Genus Geffenina Coryell and Sohn Geffenina? praelonga Cooper, n. sp. Plate 11, figures 42-44 Carapace large, elongate, ends rounded ; dorsal margin straight, venter broadly curved; overlap around entire free margin, very prominent, especially on anterior end ; hinge straight, slightly more than half length of shell, slightly depressed and notched at ends; greatest thickness and height in anterior quarter; greatest length central; median sulcus deepest midway be- tween dorsum and venter, becoming shal- lower upward; posterior sinus indistinct, resulting in poorly-defined lobe. Length, 0.95 mm; height, 0.58 mm; thickness, 0.51 mm. Golconda formation, locality 19, com- mon. Genus Jonesina Ulrich and Bassler, emend. Cooper Jonesina, in the original description, was included in the family Beyrichiidae, sub- family Kloedenellinae, the latter being sub- sequently raised to family rank. In their remarks on the Kloedenellinae Ulrich and Bassler (1908, p. 320) describe the "valves as more or less distinctly overlapping. As a rule, the overlap is confined to the ventral side and ends." The genotype by original designation is Beyrichia fastigiata Jones and Kirkby from Carboniferous (Mississippian) beds of Scotland. Unfortunately, one of the figures reproduced by Ulrich and Bassler to illustrate the genotype shows an overlap along the dorsal margin. Neither Jones and Kirkby nor Ulrich and Bassler give ade- quate description of the hingement. Kellett (1933, p. 76) explains the dorsal overlap in this figure as the ''thickened edge of the left valve showing around the cast of the right." Bassler and Kellett's (1934) de- scription of Jonesina fits several genera of Kloedenellidae equally well, for instance Sansabella. Roundy describes the hinge of Sansabella as "straight, equal in both valves and, in part, slightly lower than the dorsal margins of the two valves, giving an ex- cavated or channeled appearance in the dorsal view of a bivalved specimen." In ad- dition to the channel the Sansabella hinge contains a delta-shaped notch at each end of the hinge line, the apical point of the delta pointing to and overlapping the smaller valve. These features, namely the straight hinge line, V-shaped in cross-section, and termination at each end by a triangular notch constitute the sansabelloid hingement of many descriptions, not only of Sansa- bella, but of a number of subsequently de- cribed genera. Kellett (1933, p. 77) thinks it "would be well to place in the genus Sansabella only those species which are known to have the well developed denticulation as decribed by Roundy." By the same token it might be said that all species with the sansabelloid hinge should belong in Roundy's genus. 56 CHESTER OSTRACODES OF ILLINOIS The large number of reversed forms of Sousabella which have been discovered in the Chester series has shown the fallacy of try- ing to determine generic classification by overlap alone. Overlap, inseparably tied up with orientation, has been the subject of much discussion in recent ostracode litera- ture, and it has shown that, in every de- scription, most careful consideration must be given to these features. Since the hinge serves a most important physiological need, it seems advisable to consider variations in this feature of sufficient importance to mark generic if not greater differences in shell taxonomy. It is apparent therefore that Jonesina be- comes a very restricted genus if all species with the channeled hinge line are removed to Sansabella or to Sansabella-like genera. An emended description of Jonesina, con- sidering all points raised by recent workers, follows : Carapace ovate, somewhat elongate, thin to obese, greatest thickness posterior ; varies in lateral outline from subelliptical to an approximate parallelogram ; valves unequal; overlap around entire free margin usually prominent ; variously lobed ; hinge straight, obscurely cardine, about two-thirds as long as total length of shell; median sulcus opening into cardinal area, usually deep and elongate, before which occur one or more fairly well-defined lobes ; surface smooth or reticulate. The obesity of the posterior half of the carapace may produce a short canoe-shaped channel at the hinge line, but this is not to be confused with the straight V-shaped chan- nel running the entire length of the sansa- belloid hinge, nor is the obscure rounded notch present, as at each end of the hinge of Sansabella. Jonesina craterigera (Brady) Plate 11, figures 36-39 Beyrichia craterigera (Brady ms.) Jones, 1886, Geol. Mag. n. s., dec. 3, vol. 3, p. 439, pi. 12, figs. 7a, b, Carboniferous of Great Britain. Jonesina craterigera. Ulrich and Bassler, 1908, Proc. U. S. Nat. Mus., vol. 35, p. 324, pi. 44, figs. 13, 14.— ? Harlton, 1927, Jour. Paleon- tology, vol. 1, p. 203, pi. 32, figs. 5a, b, Lower Glenn formation. Female: length, 1.0 mm; height, 0.53 mm; thickness, 0.49 mm. Male: length, 0.75 mm; height, 0.40 mm ; thickness, 0.33 mm. Golconda formation, locality 19, rare; Glen Dean formation, locality 1, rare. Plate 11 shows two specimens, identical in lateral view, but the one from the Golconda is considerably thicker near the posterior end, whereas the Glen Dean form is thickest near the center of the shell. The specimen figured by Harlton lacks the postero-ventral truncation of the Mississip- pian form. Jonesina equilatera Cooper, n. sp. Plate 11, figures 15-16 Carapace ovate, with parallel dorsum and venter ; hinge straight, venter slightly con- vex ; ends equal in height and curvature ; sinus procentral, narrow at bottom, widen- ing toward dorsal area; overlap prominent, especially along venter ; surface smooth. Length, 1.0 mm; height, 0.60 mm; thickness, 0.36 mm. Paint Creek formation, locality 2, com- mon. /. equilatera is distinguished by its al- most symmetrical outline and by its thin- ness. Jonesina intermedia Croneis and Bristol Plate 12, figures 8-9 Jonesina interjnedia Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 75, pi. 3, figs. 10-11, Menard formation. Length, 0.64 mm; height, 0.39 mm; thickness, 0.27 mm. Vienna formation, locality 36, rare. Jonesina puncta Morey Plate 12, figures 20-21 Jonesina? puncta Morey, 1935, Jour. Paleontol- ogy, vol. 9, p. 476, pi. 54, fig. 1, Amsden formation. — Coryell and Johnson, 1939, ibid., vol. 13, p. 214, pi. 26, fig. 3, Clore formation. Jonesina consimilis Croneis and Bristol, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 74, pi. 3, figs. 29, 30, Menard formation. Kloedenella sigurdi Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 215, pi. 26, fig. 2, Clore formation. Nuferella ivellsi Coryell and Sohn, 1938, Jour. Paleontology, vol. 12, p. 602, pi. 69, fig. 9, Reynolds limestone. ' Length, 0.73 mm; height, 0.44 mm; thickness, 0.29 mm. Clore formation, locality 26, rare. KLOEDENELLIDAE 57 JONESINA SPINIGERA Coopcr, n. sp. Plate 12, figures 16-17 Carapace somewhat elongate, ends rounded ; venter broadly curved, dorsum straight ; antero-ventral truncation marked, producing distinct retral swing; greatest thickness and height back of center; great- est length central; sulcus fairly shallow, sides parallel for most of length, flaring near cardinal area ; overlap prominent only along venter ; hinge straight ; node or spine short, located in dorsal angles of each valve, that in posterior angle of left valve quite in- distinct. Length, 0.64 mm; height, 0.39 mm; thickness, 0.30 mm. Paint Creek formation, locality 24, com- mon; Golconda formation, locality 38, rare; Menard formation?, locality 32, rare. Length, 0.50 mm; height, 0.30 mm; thickness, 0.15 mm. Glen Dean formation, locality 1, rare. Genus Lochriella Scott The genus Lochriella Scott (1941) is in- termediate between Sansabella and Neokloe- denella, closely resembling the latter except for a different overlap. Sansabella and Lochriella have a prominent overlap along the free margins. Lochriella and Neokloe- denella have a channeled dorsum of variable width and depth along the posterior end of the hinge, although the Sansabella chan- nel is uniformly straight, narrow, and ex- tends along the entire hinge from notch to notch. Lochriella apparently may or may not possess the overlap at the anterior end of the hinge characteristic of all known species of Neokloedenella. JoNESiNA TENUisiNUOSA Cooper, n. sp. Plate 12, figures 6-7 Carapace elongate, ends rounded; venter slightly convex ; hinge straight ; unex- cavated, about four-fifths of total length ; sinus wide, shallow, almost at midlength ; node low, indistinct and located just in front of sinus ; anterior cardinal angle obtuse, posterior one almost 90° ; slight forward swing; overlap along free margins quite in- distinct ; surface smooth. Length, 0.73 mm; height, 0.42 mm; thickness, 0.33 mm. Golconda formation, locality 19, rare. Genus Kloedenella Ulrich and Bassler Kloedenella macer Cooper, n. sp. Plate 12, figures 10-11 Carapace elongate, thin, bisulcate; over- lap around free margins and at antero- and postero-dorsal corners, the latter resulting in sinuous hinge line in dorsal view; dorsum distinctly bowed in central region ; anterior end only slightly curved with pronounced backward swing, forming sharply rounded antero-dorsal angle ; median sulcus the larger and almost central, separated from smaller sulcus by low fold ; a broad, some- what swollen area borders median sinus on anterior side, locating greatest thickness anteriorly; widest (highest) portion of shell and small sulcus posterior. Lochriella fenriri (Coryell and Johnson) Plate 12, figures 28-29 Sansabella fenriri Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 220, pi. 25, figs. 3a, b, Clore fornmatlon. Length, 1.10 mm; height, 0.67 mm; thickness, 0.63 mm. Clore formation, locality 27, common. Lochriella reversa (Morey) Plate 12, figures 18-19 Sansabella re'versa Morey, 1935, Jour. Paleontol- ogy, vol. 9, p. 476, pi. 54, fig. 6, Amsden for- mation. Sansabella gunnari Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 220, pi. 26, figs. 11a, b, Clore formation. Re'uersabella reversa. Coryell and Johnson, idem., p. 221, p. 26, figs. 12a, b, Clore formation. Length, 1.0 mm; height, 0.67 mm; thickness, 0.50 mm. Clore formation, locality 27, common. Genus Neokloedenella Croneis and Funkhouser Neokloedenella? magna Cooper, n. sp. Plate 12, figures 42-43 Carapace ovate, wide ; dorsal and ventral margins parallel, latter slightly convex, ends rounded ; hinge line straight in posterior two-thirds of its length, then curves to left due to overlap of right valve, straight por- tion excavated in canoe-shaped channel ; 58 CHESTER OSTRACODES OF ILLINOIS overlap very slight around free margins ; sinus indistinct, wide and shallow^, located well forward of middle; greatest thickness and height near posterior end, right valve slightly higher than left ; greatest length central ; surface smooth. Length, 0.89 mm; height, 0.51 mm; thickness, 0.44 mm. Golconda formation, locality 19, com- mon. Genus Perprimitia Croneis and Gutke Perprimitia Croneis and Gutke, 1938, Bull. Deni- son Univ., Jour. Sci. Lab,, vol. 33, p. 257. This genus possesses, in addition to the features described by Croneis and Gutke, a well developed sansabelloid hinge line and a forward swing to the valves. It is believed that these features together with the dis- tinct overlap and characteristic lobation make this genus conform more closely to the Kloedenellidae than to the Primitiidae. The great variation in tumidity is thought to be sexual although no males and females of the same species have yet been designated, nor has the reversal of valves, as in Sansa- bella, been noted. Perprimitia elongata Cooper, n. sp. Plate 12, figures 30-32 Carapace elongate ; dorsal margin straight; end rounded; antero-dorsal angle sharp; node and ventral lobe not sharply differentiated but almost imperceptibly joined together; spine short, located un- usually far back from posterior end; over- lap somewhat indistinct; greatest height anterior ; greatest length and thickness cen- tral. Length, 0.45 mm; height, 0.23 mm; thickness, 0.17 mm. Paint Creek formation, locality 2, com- mon. This species may be distinguished by its unusual length, due to the relatively great distance between the spine and the ventral lobe. The figured specimen is a male. Perprimitia funkhouseri Croneis and Thurman Plate 12, figures 44-45 Perprimitia funkhouseri Croneis and Thurman, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 304, pi. 7, figs. 18, 19, Kinkaid formation. Jonesinaf tumida Croneis and Thurman, idem.,, p. 305, pi. 7, fig. 11, Kinkaid formation. Ulrichia emarginata Ulrich, 1891, Jour. Cincin- nati Soc. Nat. Hist., vol. 13, p. 203, pi. 12, figs. lOa-c, Chester series. Length 0.60 mm; height, 0.37 mm; thickness, 0.32 mm. Clore formation, locality 39, rare; Kinkaid formation, locality 28, depth 628-33 feet, rare; locality 3, abudant. The examination of a score of more specimens from a locality (No. 3) near that which furnished the types J .f tumida shows that the casts of P. funkhouseri quite often do not show the spine on the posterior end but the "largest node occupies complete posterior portion of carapace, being so swollen as to be almost uniformly convex." Otherwise the specimens are in such close agreement that I believe they are conspecific. Ulrich's species from the Clore of Kentucky is certainly a Perprimitia and very close to F. funkhouseri. Perprimitia robusta Croneis and Gutke Plate 12, figures 46-48 Perprimitia robusta Croneis and Gutke, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33,. p. 257, pi. 5, fig. 23, Renault formation. Perprimitia spinosa Croneis and Gutke, idem., p. 258, pi. 5, fig. 28, Renault formation. Length, 0.67 mm; height, 0.38 mm; thickness, 0.33 mm. Renault formation, locality 9, common; Paint Creek formation, locality 2, rare; Golconda formation, locality 17, rare. The sulcus of the holotype of P. spinosa is matrix-filled and the small node anterior to the pit is indistinguishable. For these reasons and because the form ratios are the same I consider these forms so nearly identical as to be conspecific. Perprimitia sigynae (Coryell and Johnson) Lokius sigynae Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 216, pi. 26, figs. 6a-c, Clore formation. Perprimitia tenera Cooper, n. sp. Plate 12, figures 36-38 Carapace small, subovate ; dorsal margin straight, ends rounded, antero-dorsal angles about equal; overlap inconspicuous around free margin; spine prominent, extending well above dorsum in lateral view; node KLOEDENELLIDAE 59 and lobe along the ventral margin low and somewhat indistinct; sulcus about central, quite deep; greatest height anterior, thick- ness posterior, length above midheight. Length, 0.46 mm; height, 0.27 mm; thickness, 0.24 mm. Golconda formation, locality 19, rare; Glen Dean formation, locality 23, rare. The lack of posterior obesity marks the figured specimen as a male. Genus Sansabella Roundy* Sansabella ampla Cooper, n. sp. Plate 13, figures 32-35 Carapace large, ovate, with subparallel dorsum and venter ; ends broadly rounded ; forward swing very slight ; hinge five-eighths of total shell length straight, channeled, terminated by a notch at each end; sulcus narrow in lower part, widening into car- dinal area; overlap very prominent around posterior and ventral free margins ; greatest thickness and height of female posterior, greatest thickness of male central; greatest length central; surface smooth. Length, 1.07 mm; height, 0.67 mm; thickness, 0.53 mm. Paint Creek formation, locality 2, com- mon. Sansabella bradfieldi (Coryell and Sohn) Plate 13, figures 46-51 Persansahella bradfieldi Coryell and Sohn, 1938, Jour. Paleontology, vol. 12, p. 598, pi. 69, figs. 2a, b, Reynolds limestone. Sansabella ivhitei Coryell and Sohn (not Brad- field), idem., p. 599, pi. 69, fig. 3, Reynolds limestone. Jonesina? skinneri (not J.f dubia) Croneis and Gale, 1938, Bull. Denison Univ., Jour. Scl. Lab., vol. 33, p. 265, pi. 5, fig. 29, Golconda formation. Sansabella joJinsoni (not S. lae'vis) Croneis and Thurman 1938, Bull. Denison Univ., jour. Sci. Lab., vol. 33, p. 302, pi. 7, figs. 13, 14, Kinkaid formation. — Croneis and Bristol, 1939, ibid., vol. 34, p. 70, pi. 3, figs. 5-7, Menard formation. Carapace subrhomboidal, overlap around free margin, especially prominent along venter, dorsum straight ; sinus deep, elongate vertically, extending from mid- *See discussion of Sansabella under Jonesina, p. 55; also under Lochriclla, p. 57. height almost to dorsum; forward swing distinct; hinge deeply channeled, straight; dorsal outline wedge-shaped due to obesity of posterior half; surface smooth. Length, 0,80 mm; height, 0.51 mm; thickness, 0.41 mm, Golconda formation, localities 22 (rare) and 19 (common) ; Glen Dean formation, locality 1, rare; Menard formation, locali- ties 7 (rare) and 28 (common) ; Kinkaid formation, locality 5, rare. These upper Chester forms, described under various names, are so similar that they are practically indistinguishable. I have found many reversed specimens in the Illi- nois samples (see also S. truncata, n. sp. pi. 13, figs. 36-41). All other features being equal, the reversal of valves is not considered to be of generic or even of specific character for these Kloedenellidae. The form ratio of the Reynolds forms is 1.55, Kinkaid 1.51, Menard, 1.55 and Golconda 1.55. Sansabella declivis Cooper, n. sp. Plate 13, figures 4-8 Carapace subrhomboidal, ends rounded, cardinal angles prominent ; dorsum straight, venter curved ; overlap pronounced around free margin ; sinus deep, narrow, located just in front of center; valves rise rapidly from either end to produce slightly convex outline as seen in dorsal view ; anterior end of left valve curves sharply inward form- ing narrow shelf or platform, widest on antero-ventral margin, tapering to dorsum and venter ; hinge typically sansabelloid ; surface smooth. Length, 0.89 mm; height, 0.55 mm; thickness, 0.40 mm. Golconda formation, locality 19, com- mon. The form ratio of S. declivis is quite high, about 1.6. This species may also be dis- tinguished by the narrow platform on the anterior end of the left valve. This feature is present also on the right valve but is less pronounced. Sansabella elongata Cooper, n. sp. Plate 13, figures 1-3 Carapace quite thick, elongate, sub- rhomboidal, ends rounded ; overlap most 60 CHESTER OSTRACODES OF ILLINOIS prominent on postero-ventral margin ; sulcus deep, connected with cardinal area by low saddle ; greatest length diagonal from upper posterior to lower anterior end ; shallow fur- row or flattening of shell convexity borders free margin ; hinge deeply incised ; surface finely granulose. Length, 0.75 mm; height, 0.46 mm; thickness, 0.37 mm. Paint Creek formation, locality 24, depth 2454 feet, abudant. Sansabella harrisi Croneis and Funkhouser Plate 13, figures 15-16 Sansabella harrisi Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 334, pi. 9, figs. 7, 8, Clore formation. Lamarella thurmani Croneis and Funkhouser, 1938, idem., p. 336, pi. 9, figs. 11, 12, Clore formation. Length, 0.69 mm ; height, 0.44 mm ; thickness, 0.33 mm. Clore formation, locality 26, rare; Kin- kaid formation, locality 5, common. L. thurmani is apparently a mashed speci- men of S. harrisi. Sansabella lenticularis Cooper, n. sp. Plate 13, figures 11-12 Carapace elongate, lens-shaped in dorsal outline; hinge straight, channeled, with notches at ends; greatest thickness central; anterior extremity below and posterior ex- tremity above midheight ; prominent sinus just in front of midpoint; postero-ventral truncation marked ; overlap prominent around free margin ; a short node located in postero-dorsal corner of left valve; surface smooth. Length, 0.63 mm; height, 0.38 mm; thickness, 0.28 mm. Clore formation, locality 4, rare. Sansabella njorthi (Coryell and Johnson) Reversahella njorthi Coryell and Johnson, 1939, Jour. Paleontology, vol. 13, p. 221, pi. 26, fig. 8, Clore formation. Persansabella njorthi. Sohn, 1040, idem., vol. 14, p. 159. Sansabella ovata Cooper, n. sp. Plate 13, figures 52-53 Carapace thick, ovate in lateral and dorsal views; ends rounded, dorsum slightly con- vex; forward swing very slight; overlap- prominent; sulcus deep in lower part, be- coming abruptly shallower upward toward dorsum; hinge straight and deeply chan- neled between notches; greatest thickness posterior, although but slightly greater than at anterior end ; surface smooth. Length, 0.66 mm ; height, 0.44 mm ; thickness, 0.31 mm. Paint Creek formation, locality 24, depth 2454 feet, common. This species is distinguished by the reg- ularity of the dorsal and lateral outlines and by the relative thickness of the shell. Sansabella parallela Cooper, n. sp. Plate 13, figures 42-43 Carapace somewhat rectangular, venter almost straight, parallel to dorsum ; anterior and posterior extremities above and below midheight respectively; hinge straight, very shallowly channeled, terminated at either end by prominent overlapping notch ; sinus deep, fairly broad ; posterior half tumid ; small node in postero-dorsal angle of the right valve ; surface smooth ; overlap promi- nent, especially along venter. Length, 0.72 mm ; height, 0.42 mm ; thickness, 0.32 mm. Vienna formation, locality 10, rare. Sansabella truncata Cooper, n. sp. Plate 13, figures 36-41 Carapace thick, subovate in lateral view, dorsum straight, ends rounded ; venter strongly curved, swinging anteriorly into anterior margin in flat curve, giving a somewhat truncated appearance and a strong anterior swing in lateral view ; sulcus elongate, deep, forward of center ; overlap very prominent around free margins, espe- cially venter ; greatest height central ; great- est length diagonal across shell from above center posteriorly to below center anterior- ly; hinge straight, distinctly channeled be- tween notches; short spine sometimes lo- cated in posterior cardinal angle ; surface smooth or finely granulose. Length, 0.73 mm ; height, 0.45 mm ; thickness, 0.40 mm. Golconda formation, locality 22, com- mon. LEPERDITELLIDAE 61 The lateral outline conforms closely to Geisina arcuata (Bean) but since the de- tails of the hingement of Latham's specimen are not certainly known, these thick Gol- conda specimens have been classified as a new species of Sansabella. Sansabella tumida Coryell and Sohn Plate 13, figures 29-31 Sansabella tumida Coryell and Sohn, 1938, Jour. Paleontology, vol. 12, p. 599, pi. 69, figs. 4a, b, Reynolds limestone. Length, 1.0 mm; height, 0.66 mm; thickness, 0.50 mm. Menard formation, locality 20, common. The Menard specimens are somewhat larger than those from the Reynolds forma- tion, but agree in form ratio, dorsal and lateral outlines, shape and position of the pit, and small size. Sansabella viNiTAENsis (Harlton) Plate 13, figures 44-45 Jonesina mnitaensis Harlton, 1929, Am. Jour. Scl.. ser. 5, vol. 18, p. 260, pi. 1, figs. 7a, b, Fay- etteville shale. Jonesina holli Croneis and Gutke, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 41, pi. 1, figs. 14, 15, Renault formation. Jonesina ivrighti Croneis and Gutke, idem., p. 41, pi. 1, figs. 22, 23, Renault formation. Length, 0.67 mm; height, 0.44 mm; thickness, 0.33 mm. Renault formation, locality 25, rare. Family Leperditellidae Ulrich and Bassler Genus Cyathus Roth and Skinner Cyathus vetustus Cooper, n. sp. Plate 13, figures 9-10 Carapace elongate, tumid, ends rounded ; dorsum and venter broadly curved; hinge area broad, depressed or trough-like for almost entire length, deepest in posterior quarter; articulation cardine, with pro- jection on left valve; surface reticulations fine, in rows subparallel to margins; no pit observed. Length, 0.75 mm; height, 0.40 mm; thickness, 0.38 mm. Paint Creek formation, locality 2, rare. Genus Microparaparchites Croneis and Gale Microparaparchites erectus Cooper, n. sp. Plate 13, figures 23-25 Carapace small, short, subovate; dorsum straight, venter strongly convex; ends rounded, posterior one shghtly more acute, with gentle forward swing; spines broad at base, sharply tapering, directed upward and outward slightly toward side; overlap inconspicuous ; surface smooth with slightly punctate area in front of spine just below dorsum. Length, 0.50 mm; height, 0.33 mm; thickness, 0.30 mm. Golconda formation, locality 19, rare; Vienna formation, locality 10, common; Menard formation, locality 7, common; Clore formation, locality 4, rare. M. erectus differs from M. spinosus Croneis and Gale and M. inornatus Croneis and Bristol in the lack of a "hump" or swollen area just in front of the spine. Genus Paraparchites Ulrich and Bassler Paraparchites cyclopeus (Girty) Plate 13, figures 17-19 Paraparchites nicklesi var. cyclopea Girty, 1910, Ann. New York Acad. Sci., vol. 20, p. 232, no figs., Fayetteville shale. Paraparchites robustus Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 37, pi. 1, fig. 11, Renault formation. Carapace large, tumid and ovate ; dorsal shoulder of left valve prominent ; overlap of right valve around entire free margin, greatest along antero-ventral slope ; antero- dorsal spine short ; retral swing moderate ; surface pitted ; greatest height about cen- tral ; greatest length and thickness above middle. Length, 1.36 mm; height, 1.02 mm; thickness, 0.71 mm. Renault formation, locality 25, common; Golconda formation, locality 18, rare. I believe this distinctive form, described by Girty from the Fayetteville shale, merits full specific rank because of the prominent dorsal shoulder on the left valve which Ulrich 's species from the Middle Mississip- pian does not possess. 62 CHESTER OSTRACODES OF ILLINOIS Paraparchites inornatus (McCoy) Plate 13, figures 13-14 Cy there inornata McCoy, 1844, Syn. Char. Carb. Fossils, Ireland, p. 167, pi. 23, fig. 18. Cytherella inornata. Richter, 1855, Deutsch. Geol. Ges. Zeitschr., vol. 7, p. 529, pi. 26, figs. 6, 7. Leperditia okeni inornata Jones and KIrkby, 1875, Ann. Mag. Nat. Hist., ser. 4, vol. 15, p. 54, pi. 6, fig. 2, Carboniferous of Great Britain. Leperditia inornata. Jones and Kirkby, 1896, Trans. Roy. Soc. Dublin, vol. 6, p. 183, pi. 11, figs. 15, 16; pi. 12, figs. 1-3. Paraparchites inornata. Harlton, 1927, Jour. Pal- eontology, vol. 1, p. 203, pi. 32, figs, la, b, Cisco forntiation. Delo, 1931, Washington Univ. Studies, n. ser. Sci. and Tec. no. 5, p. 42, pi. 4, fig. 2, Pennsylvanian. Paraparchites inornatus. Latham, 1933, Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, no. 12, p. 355, text fig.. Carboniferous of Great Britain. Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 256, pi. 6, fig. 33, Golconda formation. Croneis and Gutke, 1939, idem., vol. 34, p. 37, pi. 1, fig. 13, Renault formation. Length, 0.64 mm; height, 0.46 mm; thickness, 0.28 mm. Renault formation, locality 25, common; Paint Creek formation, locality 2, rare ; Gol- conda formation, locality 18, common; Glen Dean formation, locality 11, rare. Paraparchites nicklesi (Ulrich) Plate 14, figures 5-7 Leperditia nicklesi Ulrich, 1891, Jour. Cincinnati Soc. Nat. Hist., vol. 13, p. 200, pi. 18, figs, la, e, Chester series. Paraparchites nicklesi. Grabau and Shimer, 1910, North Am. Index Fossils, p. 343, figs. 1657 c-f. Girty, 1911, U. S. Geol. Survey, Bull. 439, p. 105, pi. 9, figs. 2-5, Moorefield shale, ibid., 1915, Bull. 635, p. 134, pi. 11, fig. 2, Batesville sandstone. Harlton, 1929, Am. Jour. Sci., ser. 5, vol. 18, p. 255, pi. 1, fig. 1, Fayetteville shale. Croneis, 1930, Arkan- sas Geol. Survey, Bull. 3, p. 63, pi. 15, fig. 11. Morey, 1935, Jour. Paleontology, vol. 9, p. 317, pi. 28, fig. 26, Kinderhook group, ibid., 1935, vol; 9, p. 475, pi. 54, fig. 8, Ams- den formation; ibid., 1936, vol. 10, p. 115, pi. 17, fig. 26, Chouteau limestone. Coryell and Johnson, 1939, idem., vol. 13, p. 214, pi. 25, fig. 1, Clore formation. Length, 1.43 mm; height, 1.02 mm; thickness, 0.71 mm. Renault formation, locality 25, rare; Golconda formation, locality 19, common; Clore formation, locality 27, common ; Kin- kaid formation, locality 5, rare. Paraparchites ovatus Cooper, n. sp. Plate 14, figures 1-2 Carapace strongly convex, symmetrical in dorsal view ; subovate, in lateral view with distinct retral swing; dorsal margin almost straight; spine indistinct near dorsal mar- gin, but well back from anterior end ; over- lap very slight, especially on posterior mar- gin ; greatest height well back of midlength ; greatest thickness slightly forward, above center. Length, 1.17 mm; height, 0.83 mm; thickness, 0.58 mm. Clore formation, locality 26, rare. Genus Proparaparchites Cooper, n. gen.. Carapace ovate, ends symmetrical or nearly so, sides convex, overlap around free margin only; hingement straight and sim- ple; surface smooth, without pits, nodes, or spines. Genotype — P. ovatus n. sp., Kinkaid formation. This genus differs from other Leperditel- lidae in the symmetrical lateral and dorsal outlines and in the lack of dorsal overlap. Proparaparchites fabulus Cooper, n.sp. Plate 14, figures 3-4 Carapace ovate, bean-shaped, laterally symmetrical, ends rounded ; venter convex, dorsum slightly concave; dorsal outline ovate, hinge straight posteriorly, curving slightly toward left valve anteriorly; over- lap moderate ; surface smooth. Length, 0.53 mm ; height, 0.29 mm ; thickness, 0.23 mm. Renault formation, locality 13, rare. Differs from P. ovatus n. sp. in the greater form ratio, 1.78. Proparaparchites ovatus Cooper, n. sp. Plate 14, figures 8-9 Carapace ovate laterally, ends equally rounded ; venter slightly convex, dorsum straight ; overlap slight, uniform around free margin ; dorsal outline elliptical ; hinge line straight, slightly but very narrowly channeled in central portion ; surface smooth. Length, 0.50 mm ; height, 0.30 mm ; thickness, 0.25 mm. Kinkaid formation, locality 3, abundant. PRIMITIIDAE 63 Family Primitiidae Ulrich and Bassler Genus Carboprimitia Croneis and Funkhouser Carboprimitia campa Cooper, n. sp. Plate 14, figures 12-15 Carapace subovate ; hinge straight, slight- 1}^ depressed or channeled between notches; overlap equal, complete at each end, much greater along venter ; anterior furrow paral- lel to free margin, merging with depressed overlap area below and with flat, sinus-like area in antero-dorsal quarter ; pit wide, deep, antemedian, undefined around margins ; cardinal area flat, except on posterior half which barely rises above hinge; greatest length central ; greatest height and thick- ness post-central through shoulder on right valve. Length, 1.04 mm; height, 0.70 mm; thickness, 0.50 mm. Menard formation, locality 7, common. This species may be recognized by the low dorsal protuberance of the right valve, and the deeply channeled, very large over- lap along the ventral free margin. Carboprimitia longula Cooper, n. sp. Plate 14, figures 26-29 Carapace large, thick, elongate, surface smooth ; pits deep, slightly forward of mid- dle ; dorsum flat, sloping toward hinge, shoulder on right valve projecting above hinge ; central portion of hinge depressed, channel thus formed terminated by the notch of the sansabelloid articulation ; over- lap complete around free margin, greatest back of middle of venter ; channel, parallel to and just inside anterior margin, marks left valve ; greatest height and thickness posterior, through shoulder of right valve ; greatest length through middle of shell. Length, 1.10 mm; height, 0.73 mm; thickness, 0.53 mm. Clore formation, locality 4, common. C. longula is similar to previously de- scribed species but may be distinguished by the greater length (form ratio, 1.6) and by the greater depth of the pits. Carboprimitia rotunda Croneis and Funkhouser Plate 14, figures 16-19 Carboprimitia rotunda Croneis and Funkhouser, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 338, pi. 9, figs. 3, 4, Clore forma- tion. Carboprimitia rotunda var. tujnida Croneis and Funkhouser, 1938, idem., p. 339, pi. 9, figs. 5, 6, Clore formation. Length, 1.0 mm; height, 0.71 mm; thick- ness, 0.50 mm. Vienna formation, locality 10, rare; Me- nard formation, locality 7, abundant; Clore formation, locality 4, abundant; Kinkaid formation, locality 5, abundant. Genus Coryellina Bradfield CORYELLINA ELEGANS (Croneis and Gutke) Plate 14, figures 34-36 Perprimitia elegans Croneis and Gutke, 1939, Bull. Denison Univ., Jour. Sci. Lab., vol. 34, p. 38, pi. 1, figs. 3, 4, Renault formation. Length, 0.60 mm; height, 0.40 mm; thickness, 0.40 mm. Renault formation, locality 9, rare. This species closely resembles C. capax Bradfield in the general dorsal outline, character of incised articulation on the free margins, obesity, median sulcus, and in the presence of small spines. It differs in the lack of channeling of the hinge line and lacks the development of the posterior end, which is produced to meet the spine. In C. elegans, the spine rises from the posterior margin without interruption of the regular curvature of the shell. Genus Tetrasacculus Stewart Tetrasacculus mirablilis (Croneis and Gale) Plate 14, figures 44-53 Pterocodella mirablilis Croneis and Gale, 1938, Bull. Denison Univ., Jour. Sci. Lab., vol. 33, p. 261, pi. 5, figs. 25-27, Golconda formation. JVorkmanella distincta Croneis and Gale, idem., p. 277, pi. 5, fig. 11, Golconda formation. Male: length, 0.70 mm; height, 0.39 mm; thickness, 0.38 mm. Female: length, 0.87 mm; height, 0.45 mm ; thickness, 0.44 mm. Golconda formation, locality 28, com- mon; Glen Dean formation, locality 23, depth 230-35 feet, common. 64 CHESTER OSTRACODES OF ILLINOIS Evidence for the association of these peculiar Chester forms with Tetrasacculus is furnished by the male specimen here figured. Such features as the centro-ventral and posterior lobes, lateral outline, dorsal and ventral aspect in the male, and the number and position of the brood pouches in the female make this classification rather certain. Work?na}iella of Croneis and Gale seems indistinguishable from the male Tet- j'dsac cuius. Family Youngiellidae Jones and Kirkby Genus Moorea Jones and Kirkby MooREA? CIRCINCTA Cooper, n. sp. Plate 14, figures 37-40 Carapace ovate, subelliptical, ends round- ed ; dorsum and venter very slightly con- vex, almost straight; margins bounded by low, narrow ridge parallel to dorsal and ventral margins, subparallel to each end, enclosing broad, gently convex or almost flat area; sides parallel; overlap very slight but continuous around free margins ; dorsum channeled by depressed hinge, ending with a notch at either end. Length, 0.52 mm; height, 0.28 mm; thickness, 0.20 mm. Paint Creek formation, locality 2, rare. This species agrees very closely to the generic description of Moorea, but is clas- sified with this genus with some hesitation. The encircling ridge of M.f circincta is es- sentially in one plane while that of M. obesa Jones and Kirkby and M. tenuis Jones and Kirkby show, in the ventral view, a distinct bending toward the line of articu- lation. No adequate description of the hinge is available for Moorea; the hinge of the Paint Creek form is sansabelloid. If this holds for all species, then a recon- sideration of family affinities is necessary. Genus Moorites Coryell and Billings MooRiTES BREVis Cooper, n. sp. Plate 14, figure 43 Carapace short ; retral swing slight ; dor- sal and ventral margins somewhat convex; valves thickened along entire free margin, especially anteriorly and ventrally; surface punctuate. Length, 0.47 mm; height, 0.27 mm. Vienna formation, locality 10, common. The form ratio of 1.9 shows that this species is a shorter form than M. rhomboi- dalis (Croneis and Gutke), which it closely resembles in other respects. Moorites convexus Cooper, n. sp. Plate 14, figures 32-33 Carapace ovate, ends rounded, anterior cardinal angle being more obtuse; dorsum straight, venter nearly so, parallel to dor- sum ; thickening of shell apparent only at extremities ; surface shallowly pitted ; sides distinctly convex; hinge somewhat chan- neled. Length, 0.47 mm; height, 0.23 mm; thickness, 0.20 mm. Paint Creek formation, locality 2, rare. M. convexus has the same lateral con- figuration (and form ratio) as M. rhom- boidalis (Croneis and Gutke), but the latter lacks the convexity of the carapace in dorsal view, and possesses a thickening of the shell around the ventral margin. Moorites elongatus Cooper, n. sp. Plate 14, figures 20-21 Carapace elongate, dorsum and venter straight, parallel; ends rounded, especially posteriorly, with dorsal and ventral angles essentially equal; antero-cardinal angle prominent; surface smooth. Length, 0.43 mm; height, 0.18 mm; thickness, 0.12 mm. Renault formation, locality 9, common ; Paint Creek formation, locality 2, rare. This species differs from M. rhomboidalis (Croneis and Gutke) and M. convexus n. sp. in its relatively greater length (form ratio 2.35). Moorites intermedius Cooper, n. sp. Plate 14, figures 41-42 Carapace elongate, with distinct retral swing; sides slightly convex; ventral mar- gin concave; dorsum straight; ends round- ed ; valves thickened on ends and around ventral angles, this thickness diminishing to almost nothing at middle of ventral mar- gin ; surface granulose or finely reticulate. Length, 0.47 mm ; height, 0.20 mm ; thickness, 0.13 mm. Renault formation, locality 9, common. REFERENCES 65 This species is distinguished by its con- cave venter and the absence of the thick- ened margin in the middle of the venter. Its form ratio of 2.25 is intermediate be- tween M. elongatus n. sp. and M. rhomboi- dalis (Croneis and Bristol). MOORITES RHOMBOIDALIS (Croneis and Bristol) Plate 14, figures 30-31 Youngiella rhomhoidalis Croneis and Bristol, 1939, Jour. Paleontology, vol. 34, p. 100, pi. 3, fig. 23, Menard formation. Length, 0.50 mm; height, 0.25 mm; thickness, 0.20 mm. Renault formation, locality 9, rare ; Paint Creek formation, locality 18, rare; Gol- conda formation, locality 19, common; Glen Dean formation, locality 1, rare; Vienna formation, locality 10, common; Menard formation, locality 7, rare; Clore formation, locality 28, depth 689-94 feet, common ; Kinkaid formation, locality 5, rare. This distinctive species, having a form ratio of 2.14, with slightly convex, subpar- allel sides, and a distinctly elevated rim around the free margins, has been recog- nized in all marine Chester formations in Illinois, the Reynolds of West Virginia and the Fayetteville of Oklahoma and Arkansas. REFERENCES Adams, G. I. and Ulrich, E. O., Zinc and lead deposits of northern Arkansas: U. S. Geol. Survey, Prof. Paper 24, 1904. Adams. G. I. and Ulrich, E. O., U. S. Geol. Sur- vey, Geol. Atlas (Fayetteville Folio) No. 119, 1905. Bassler, R. S. and Kellett, Betty, Bibliographic index of Paleozoic Ostracoda: Geol. Soc. Am., Spec. Paper 1, 1934. Branson, E. B. and Greger, D. K., Amsden for- mation of the east slope of the Wind River Mountains of Wyoming and its fauna: Bull. Geol. Soc. Am., vol. 29, pp. 309-326, 1918. Coryell, H. N. and Johnson, Samuel C, Ostra- coda of the Clore limestone: Jour. Paleon- tology, vol. 13, pp. 214-224, pis. 25, 26, 1939. Coryell, H. N. and Sohn, I. G., Ostracoda from the Mauch Chunk, Mississippian, of West Virginia: Jour. Paleontology, vol. 12, pp. 596-603, pi. 69, 1938. Croneis, Carey, Geology of the Arkansas Paleo- zoic area: Arkansas Geol. Survey, Bull. 3, 1930. Croneis, Carey and Bristol, Hubert M., New ostracodes from the Menard formation: Bull. Denison Univ., Jour. Sci. Lab., vol. 34, pp. 65-102, pis. 3, 4, 1939. Croneis, Carey and Funkhouser, Harold J., New ostracodes from the Clore formation: idem. vol. 33, pp. 331-360, pis. 9, 10, 1938. Croneis, Carey and Gale, Arthur S., Jr., New ostracodes from the Golconda formation: idem., vol. 33, pp. 251-295, pis. 5, 6, 1938. Croneis, Carey and Gutke, Ralph L., New os- tracodes from the Renault formation: idem., vol. 34, pp. 33-63, pis. 1, 2, 1939. Croneis, Carey and Thurman, Franklin A., New ostracodes from the Kinkaid forma- tion: idem., vol. 33, pp. 297-330, pis. 7, 8, 1938. Darton, N. H., Comparison of the stratigraphy of the Black Hills, Big Horn Mountains, and Rocky Mountain Front Range: Bull. Geol. Soc. Am., vol. 15, pp. 394-401, 1904. Geis, H. L., Some ostracodes from the Salem lime- stone, Mississippian, of Indiana: Jour. Paleontology, vol. 6, pp. 149-188, pis. 22-26, 1932. Girty, George H., New genera and species of Carboniferous fossils from the Fayetteville shale of Arkansas: Ann. New York Acad. Sci., vol. 20, pp. 232-236, 1910. Harlton, Bruce H., Some upper Mississippian (Fayetteville) and lower Pennsylvanian (Wapanucka-Morrow) Ostracoda of Okla- homa and Arkansas: Am. Jour. Sci., ser. 5, vol. 18, pp. 254-270, pis. 1, 2, 1929. Kellett, Betty, Ostracodes of the upper Pennsyl- vanian and lower Permian strata of Kan- sas; I. The Aparchitidae, Beyrichiidae, Glyptopleuridae, Kloedenellidae, Kirkby- idae, and Youngiellidae: Jour. Paleontol- ogy, vol. 7, pp. 59-108, pis. 13-16, 1933. Kellett, Betty, Ostracodes of the upper Pennsyl- vanian and lower Permian strata of Kan- sas, HI: Jour. Paleontology, vol. 9, pp. 144-146, 1935. Knight, J. B., Some Pennsylvanian ostracodes from the Henrietta formation of eastern Missouri: Jour. Paleontology, vol. 2, pp. 229-267, pis. 30-34; pp. 318-336, pis. 43, 44, 1928. Latham, Mary A., Scottish Carboniferous Ostra- coda: Trans. Roy. Soc. Edinburgh, vol. 57, pt. 2, no. 12, pp. 351-395, 25 text figs., 1932. Morey, Philip S., Ostracoda from the Amsden formation, Wyoming: Jour. Paleontology, vol. 9, pp. 474-482, pi. 54, 1935. Reger, David B., Mercer, Monroe and Summers counties: West Virginia Geol. Survey, pp. 301, 426, 1926. 66 CHESTER OSTRACODES OF ILLINOIS Rom, Robert, A revision of the ostracode genus K'lrkhya and subgenus Amphissites: Wag- ner Free Inst. Sci., Publ. 1, pp. 1-55, pis. 1-3, 1929. RouNDY, P. v., Mississippian formations of San Saba County, Texas: U. S. Geol. Survey, Prof. Paper 146, pp. 5-8, pi. 1, 1926. ScoTT, Harold W., Some Carboniferous strati- graphy in Montana and northwestern Wy- oming: Jour. Geologv, vol. 43, pp. 1011- 1032, 1935. Scott, Harold W., Ostracodes from the Upper Mississippian of Montana: Jour. Paleon- tology, in press, 1941. SiMONDS, F. W., Arkansas Geol. Survey, Ann. Rept. 1888, vol. 4, pp. 26, 42-49, 1891. SoHN, I. G., Check list of Mississippian Ostra- coda of North America: Jour. Paleontology, vol. 14, pp. 154-160, 1940. Ulrigh, E. O., New and little-known American Paleozoic Ostracoda: Jour. Cincinnati Soc. Nat. Hist., vol. 13, pp. 104-137, 172-211, pis. 7-18, 1890, 1891. Ulrich, E. O. and Bassler, R. S., New American Paleozoic Ostracoda; preliminary revision of the Beyrichiidae, with descriptions of new genera: Proc. U. S. Nat. Museum, vol. 35, pp. 227-340, pis. 37-44, 1908. Weller, J. Marvin, Geology and oil possibilities of extreme southern Illinois: Illinois Geol. Survey, Rept. Inv. 71, 1940. Weller, J. Marvin and Sutton, A. H., Missis- sippian border of Eastern Interior Basin: Bull. Am. Petrol. Geol., vol. 24, pp. 765- 858, 1940. White, David, Fossil flora of the Wedington sandstone member of the Fayetteville shale: U. S. Geol. Survey Prof. Paper 186, pp. 15-17, 1937. PLATES AND EXPLANATIONS Explanation of Plate 1 Figs. 1-3 Acratia obtusa Cooper, n. sp. Dorsum, left valve, and venter of holotype, x30. Paint Creek formation, loc. 2 p. 24 4-8 Triceratina inconsueta (Croneis and Gutke). 4 and 6, anterior and posterior ends; 5, 7, and 8, left valve, venter, and dorsum, x40. Renault formation, loc. 9 . . p. 24 9-10 Bairdia golcondensis Croneis and Gale. Dorsum and right valve, x40. Golconda formation, loc. 17 11-12 Bairdia brevis Jones and Kirkby. Dorsum and right valve, corroded along postero- dorsal slope, x20. Menard formation, loc. 15 p. 25 13-16 Monoceratina furcula Croneis and Gale. 13, posterior end; 14-16, dorsum, right valve, and venter, x40. Menard formation, loc. 28 17-20 Bairdia granireticulata Harlton. Dorsum and right valve of two specimens from the Paint Creek (17, 18) and Golconda formations (19, 20) ; x20. Localities 18 and 17 p. 26 21-22 Bairdia aequa Cooper, n, sp. Dorsum and right valve of holotype, x30. Renault formation, loc. 13 p. 24 23-26 Monoceratina celsalobata Cooper, n. sp. 23, posterior end ; 24-26, dorsum, right valve and venter of holotype, x40. Golconda formation, loc. 17 p. 23 27-28 Bairdia cestriensis Ulrich. Dorsum and right valve, x20. Golconda formation, loc. 19 p. 25 29-32 Monoceratina opima Cooper, n. sp. 29, posterior end; 30-32, dorsum, right valve and venter of holotype, x40. Renault formation, loc. 9 p. 23 33-34 Bairdia attenuata Girty. Dorsum and right valve, x20. Glen Dean formation, loc. 1 p. 25 35-37 Acratia tumida Cooper, n. sp. Dorsum, right valve, and venter of holotype, x30. Kinkaid formation, loc. 3 p. 24 38-39 Bairdia galei Croneis and Thurman. Dorsum and right valve, x30. Kinkaid forma- tion, loc. 28 40-42 Acratia ?nucronata Cooper, n. sp. Dorsum, left valve and venter of holotype, x30. Glen Dean formation, loc. 1 ' p. 24 43-44 Bairdia curvis Cooper, n. sp. Dorsum and right valve of holotype, x20. Paint Creek formation, loc. 32 p. 25 45-46 Bairdia delicata Morey. Dorsum and right valve, x30. Menard formation, loc. 20 . p. 25 47-48 Bairdia aculeata Cooper, n. sp. Dorsum and right valve of holotype, x30. Kinkaid formation, loc. 3 p. 24 [68] Illinois State Geological Survey Rept. Inv. 77, Plate 1 ^^^im^^i mm^M «^^^"" 7 # AS ^^^^^^2 a3 ^^^^^gs ^^BH^^^35 ■, 33 34 ^^^^^^fe^ ' •'■^'^pilB 41 44 ^^^^^ Illinois State Geological Survey Rept. Inv. 77, Plate 2 Explanation of Plate 2 (The dorsum and right valve of each specimen shown, except as noted) Figs. 1-2 Bairdia insolens Cooper, n. sp. Holotype, x20. Renault formation, loc. 12 . . . p. 26 3-4 Bairdia cf. suhelongata Jones and Kirkby. x20. Golconda formation, loc. 19 . . . p. 26 5-6 Bairdia suhtila Cooper, n. sp. Holotype, x20. Kinkaid formation, loc. 3 .... p. 26 7-8 Bairdia impendere Cooper, n. sp. Holotype, x20. Renault formation, loc. 14 . . p. 26 9-10 Bairdia renaultensis Croneis and Gutke, x20. Renault formation, loc. 25 11-12 Bairdia sinuosa Cooper, n. sp. Holotype, x30. Kinkaid formation, loc. 5 . . . . p. 26 13-14 Bairdia osorioi Croneis and Gale, x20. Golconda formation, loc. 8 15-16 Bairdiolites hremrostris Cxone\% 2indT\i\ixm2in. x30. Kinkaid formation, loc. 5 . . p. 26 17-18 Bairdia mccoyi Croneis and Gutke, x20. Glen Dean formation, loc. 1 19-20 Bairdiolites hulhosus Cront'is, 2indBr\s>to\,y.'?)Q. Menard formation, loc. 20 . . . . p. 27 21-22 Bairdiolites ovatus Croneis and Funkhouser, x30. Kinkaid formation, loc. 5 . . . p. 27 23-24 Bairdiolites elongatus Croneis and Funkhouser, x30. Kinkaid formation, loc. 5 25-26 Bairdiolites crescentis Croneis and Gale, x30. Golconda formation, loc. 17 27-28 Bairdiolites fornicatus Cooper, n. sp. Holotype, x30. Menard formation, loc. 15 . p. 27 29-30 Bairdiolites crassus Cooper, n. sp. Holotype, x30. Clore formation, loc. 28 . . . p. 27 31-32 Beyrichiopsis hrynhildae Coryell and Johnson. Dorsum and left valve, x30. Clore formation, loc. 27 33-34 Beyrichiopsis thori Coryell and Johnson. Dorsum and left valve, x30. Clore forma- tion, loc. 27 35-36 Bythocypris amsdenensis Morey, x40. Fayetteville shale, loc. 31 p. 28 37-38 Bairdiolites tenuis Cooper, n. sp. Holotype, x30. Renault formation, loc. 13 . . . p. 27 39-40 Bairdiolites procerus Cooper, n. sp. Holotype, x30. Kinkaid formation, loc. 6 . . . p. 27 41-42 Bairdiolites vulgaris Cooper, n. sp. Holotype, x30. Paint Creek formation, loc. 2 . . p. 28 43-44 Bairdiolites platypleurus Croneis and Gale, x30. Renault formation, loc. 25 71 Explanation of Plate 3 Figs. 1-2 Bythocypris dorensis Croneis and Funkhouser. Dorsum and right valve, x40, Kin- kaid formation, loc. 6 p. 28 3-6 Bythocypris concava Cooper, n. sp. Dorsum and right valve; 3, 4 holotype, Kinkaid formation, loc. 6 ; 5, 6, Vienna formation, loc. 10, x40 p. 28 7-8 Bythocypris gihha Cooper, n. sp. Dorsum and right valve. Holotype, x40. Renault formation, loc. 9 p. 28 9-10 Bythocypris modica Cooper, n. sp. Dorsum and right valve. Holotype, x40. Paint Creek formation, loc. 24 p. 28 11-13 Bythocypris ovata Cooper, n. sp. Dorsum, right valve, and venter. Holotype, x30. Paint Creek formation, loc. 21 p. 29 14-16 Healdia cornigera (Jones and Kirkby). Posterior end, dorsum, and right valve, x40. Golconda formation, loc. 19 p. 30 17-19 Healdia aequahilis Cooper, n. sp. Posterior end, dorsum, and right valve. Holotype, x40. Renault formation, loc. 25 p. 30 20-21 Bythocypris opitna Cooper, n. sp. Dorsum and right valve. Holotype, x30. Gol- conda formation, loc. 22 p. 29 22-28 Bythocypris truncata Cooper, n. sp. 22-25, dorsum, right valve, venter, and anterior end, x40 ; 26-28, dorsum, posterior end, and right valve of holotype, x30. Renault formation, loc. 25 p. 29 29-30 Bythocypris fahalis Cooper, n. sp. Dorsal view and right valve. Holotype, x20. Paint Creek formation, loc. 23 p. 28 31-33 Healdia goniapleura Croneis and Bristol. Posterior end, right valve, and dorsum, x40. Vienna formation, loc. 10 34-36 Cribroconcha fornicata Cooper, n. sp. Posterior end, dorsum and right valve. Holo- type, x40. Paint Creek formation, loc. 24 p. 30 37-42 Cribroconcha costata Cooper, n. sp. 37-39, dorsum, left valve, and posterior end; ^Q-A2y posterior end, right valve, and dorsum of genotype, x40. Renault for- mation, loc. 9 p. 29 43-45 Healdia elliptica Cooper, n. sp. Posterior end, dorsum, and right valve. Holotype, x40. Golconda formation, loc. 19 p. 31 46-49 Healdia caneyensis Harlton. Dorsum and right valves of two specimens, x40. Glen Dean formation, loc. 11 p. 30 50-51 Healdia fayettevillensis Harlton. Dorsum and right valves. x40. Clore formation, loc. 4 p. 31 52-54 Healdia exilis Cooper, n. sp. Posterior end, dorsum and right valve. Holotype, x40. Vienna formation, loc. 10 p. 31 72 Illinois State Geological Survey Rept. Inv. 77, Plate 3 •it t^..^^-lt^ ^^^ ^^^^ 4^0f£ ^^^^' ^^Hllll^^7 ^^BBI^^ ^HJI^si ^Pji^BHI^u Illinois State Geological Survey Rept. Inv. 77, Plate 4 Explanation of Plate 4 Figs. 1-2 Healdia ornata Morey. Dorsum and right valve, x40. Glen Dean formation, loc. 11 p. 32 3-5 Healdia menisca Cooper, n. sp. Posterior end, dorsum, and right valve. Holotype, x40. Paint Creek formation, loc. 24 p. 31 6-7 Healdia minuta Cooper, n. sp. Dorsum and left valve. Holotype, x40. Paint Creek formation, loc. 24 p. 31 8-10 Healdia mucronata Cooper, n. sp. Posterior end, dorsum, and right valve. Holotype, x40. Golconda formation, loc. 19 p. 31 11-12 Healdia vinitaensis Harlton. Dorsum and right valve, x40. Vienna formation, loc. 10 p. 32 13-14 Healdia tenuicosta Cooper, n. sp. Dorsum and right valve. Holotype, x40. Clore formation, loc. 4 p. 32 15-17 Healdia ovoidea Cooper, n. sp. Posterior end, dorsum and right valve. Holotype, x40. Golconda formation, loc. 19 p. 32 18-20 Healdia radinula Cooper, n. sp. Posterior end, dorsum and right valve. Holotype, x40. Paint Creek formation, loc. 24 p. 32 21-22 Incisurella lata Cooper, n. sp. Dorsum and right valve. Holotype, x40. Paint Creek formation, loc. 14 p. 33 23-24 Microcheilinella cordata Cooper, n. sp. Dorsum and right valve. Holotype, x40. Kinkaid formation, loc. 3 . p. 33 25-26 Macrocypris oirata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Kinkaid formation, loc. 3 p. 34 27-29 Incisurella prima Cooper, n. sp. Posterior end, dorsal view, and right valve. Geno- type, x40. Renault formation, loc. 9 p. 32 30-31 Macrocypris acuminata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Menard formation, loc. 30 p. 34 32-34 Seminolites ovalis Cooper, n. sp. Posterior end, dorsum and right valve. Holotype, x40. Renault formation, loc. 13 p. 33 35-38 Microcheilinella ohesa Cooper, n. sp. Posterior end, dorsum, right valve and venter. Holotype, x40. Menard formation, loc. 28 p. 33 39^0 Microcheilinella per gracilis Croneis and Gale. Dorsum and right valve, x40. Vienna formation, loc. 10 41 — 4-2 Seminolites? reversus Cooper, n. sp. Dorsum and left valve, Holotype, x40. Gol- conda formation, loc. 17 p. 34 43-44 Macrocypris reginni Coryell and Johnson. Dorsum and left valve, x30. Kinkaid formation, loc. 3 45-46 Microcheilinella? exilis Cooper, n. sp. Dorsum and right valve. Holotype, x40. Renault formation, loc. 9 p. 33 47-49 Microcheilinella tumida Cooper, n. sp. Dorsum, right valve, and venter. Holotype, x40. Golconda formation, loc. 17 p. 33 50-52 Seminolites sohni Croneis and Bristol. Posterior end, right valve and dorsum, x40. Golconda formation, loc. 19 53-55 Seminolites symmetricus Cooper, n. sp. Posterior end, dorsum and right valve. Holotype, x40. Paint Creek formation, loc. 2 p. 34 75] Explanation of Plate 5 Figs. 1-6 Tetratylus ellipticus Cooper, n. sp. Dorsum, left valve and posterior end. Genotype (figs. 1-3), x40. Paint Creek formation, loc. 24 p. 35 7 Tetratylus elongatus Cooper, n. sp. Left valve. Holotype, x40. Paint Creek forma- tion, loc. 24 p. 35 8-12 Tetratylus menardensis (Croneis and Bristol). 8, 9, left valve and posterior end, ' Menard formation, loc. 28 ; 10-12, dorsum, left valve and posterior end. Paint Creek formation, loc. 24, x40 p. 35 13-14 Beyrichia contracta Cooper, n. sp. Dorsum and right valve. Holotype, x40. Golconda formation, loc. 18 p. 35 15-17 Beyrichia sagitta Cooper, n. sp. Dorsum, posterior end, and right valve. Holotype, x40. Paint Creek formation, loc. 2 p. 35 18-19 Beyrichia placida Croneis and Gale. Dorsum and left valve, x40. Golconda forma- tion, loc. 22 20-21 Cavellina congruens Cooper, n. sp. Dorsum and left valve. Holotype, x30. Clore formation, loc. 4 p. 36 22-23 Cavellina bransoni (Morey). Dorsum and right valve, x30. Kinkaid formation, loc. 3 p. 35 24-25 Cavellina coryelli Croneis and Gale. Dorsum and left valve, x30. Clore formation, loc. 4 26-27 Ca'vellina hoeniri Coryell and Johnson. Dorsum and left valve, x40. Clore forma- tion, loc. 4 28-29 Cavellina dispar Cooper, n. sp. Dorsum and left valve. Holotype, x30. Menard formation, loc. 20 p. 36 30-31 Cavellina parallela Croneis and Gale. Dorsum and left valve, x30. Paint Creek formation, loc. 18 32-33 Cavellina perplexa Croneis and Funkhouser. Dorsum and left valve, x30. Clore formation, loc. 4 34-36 Cavellina exila Cooper, n. sp. Dorsum, left valve, and posterior end. Holotype, x20. Renault formation, loc. 13 p. 36 37-38 Cavellina librata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Clore for- mation, loc. 4 p. 36 39-40 Cavellina parva Cooper, n. sp. Dorsum and left valve. Holotype, x30. Vienna formation, loc. 10 p. 37 41-42 Cavellina longula Cooper, n. sp. Dorsum and left valve. Holotype, x30. Golconda formation, loc. 22 p. 36 43-44 Cavellina geisi (Croneis and Gale). Dorsum and left valve, x30. Vienna forma- tion, loc. 10 p. 36 45-48 Cavellina ovatiformis (Ulrich). Dorsum and left valve. 45, 46, Kinkaid forma- tion, loc. 5 ; 47, 48, Fayetteville shale, loc. 31, x30 p. 37 49-50 Cavellina glandella (Whitfield). Dorsum and left valve, x30. Kinkaid formation, loc. 3 p. 36 [76 Illinois State Geological Survey Rept. In v. 77, Plate 5 Illinois State Geological Survey Bept. Inv. 77, Plate 6 Explanation of Plate 6 Figs. 1-2 Sargentina asulcata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Kinkaid formation, loc. 5 p. 39 3-4 Paracavellina o^ata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Menard formation, loc. 15 p. 37 5-6 Paraca'vellina elliptica Cooper, n. sp. Dorsum and left valve. Genotype, x20. Gol- conda formation, loc. 17 p. 37 7-8 Paracavellina pinguis Cooper, n. sp. Dorsum and left valve. Holotype, x30. Gol- conda formation, loc. 17 p. 38 9-10 Sargentina crassimarginata Cooper, n. sp. Dorsum and left valve. Holotype, x30. Kinkaid formation, loc. 5 p. 39 11-12 Sulcella o 20, 58 spinosa 58 tenera 20, 58, 9 1 turrita • 20 Persansahella bradfieldi 59 njorthi 60 Pitkin limestone 4-1 Platychilus 10, 38 ovoides 10, 16, 38, 79 Polytylites • (>> 51 ambitus 8, 18, 51, 87 biforatus 18, 52, 87 bradfieldi 18, 52, 87 concavus 11, 18, 52 rrassus 12, 18, 52, 87 directus 10, 18, 52, 87 di'versus 10, 18, 52, 87 elongatus 18, 52, 87 fossilis 18, 52, 87 geniculatus 18, 52, 87 gro'uei 8, 18, 53 nodobliqiius 18, 53, 87 quincollinus 18, 53 , 87 reticulatus 11, 18, 53, 87 similis ...10, 18, 53 Primitiidae 20, 63 Primitia cestriensis 10, 21 cestriensis caldivellensis 11, 21 fayettemllensis 21 granimarginata 10, 21 sefninalis 21 simulans 10, 21 subaequata H, 21 Primitiopsis? striatus .44 Proparaparchites 62 fabulus 8, 20, <52, 95 o'vatus 12, 20, 62, 95 Pseudoparaparchites 10 aclis 12, 20 Pterocodella 23 inconsueta 23, 24 mirablilis 63 R Reelsville limestone 7 References 65 Renault formation 6, 7, 8 Restricted species in — Clore 11 Glen Dean 10 Golconda 9 Kinkaid 11 Menard 11 Paint Creek ....9 Renault 8 Vienna 10 Reynolds formation 5, 8, 12, 13 Reversabella reversa 57 njorthi 60 Ruma formation 7 s Sample sandstone and shale 7 Sansabella 55, 57, 59 ampla . 9, 20, 59, 92 amsdenensis 20 bradfieldi 20, 59, 92 Sansabella, cont'd. " Pages declems 10, 20, 59, 92 fdubia 20 elongata 9, 20, 59, 92 fenriri 57 gunnari 57 harrisi 10, 13, 20, 60, 92 johnsoni 59 lenticularis 11, 20, 60, 92 njorthi 11, 20, 60 o'vata 9, 20, 60, 92 parallcla 10, 20, 60, 92 sulcata 20 truncata 10, 20, 60, 92 tumida 20, 61 ^ 92 mnitaensis 8, 20, 61, 92 ivhitei 59 Sargentina 10, 38, 44 allani 11, 16, 38, 79 asulcata 11, 12, 16, 38, 79 crassimarginata 12, 16, 38, 79 forsetii "... 38 Savagella 47 f acuminata 19, 47, 88 lindahli 19 rhomboidalis 19 Seminolites 33 o'valis 8, 15, 33, 75 re'uersus 9, 15, 34, 75 . sohni 15 symmetricus 9, 15, 34, 75 Siberia limestone 7 Stratigraphic range 5 Sulcella 7, 39 celsa 9, 16, 39, 79 crassimarginata 38 o'uata 9, 16, 39, 79 Ste. Genevieve formation 12 T Talcott member 12, 13 Tar Springs sandstone 7 Tensleep formation 12 Tetrasacculus 9, 63 mirablilis 9, 21, 63, 95 Tetratylus 7, 34 ellipticus 9, 15, 35, 76 elongatus 9, 15, 35, 76 menardensis 15, 35, 76 Triceratina 23 inconsueta 14, 24, 68 V Venula 10, -^^ striata 10, 17, 44, 84 Verrucosella golcondensis 39 Vienna formation 6, 7, 8, 10 w Waltersburg sandstone 6, 7 JVaylandella cornigera 30 Webster Springs member 13 Wedington sandstone 13 Wickcliff e sandstone 7 fVorkmanella disjuncta 63 Y \ankeetown chert 7 Youngiellidae 21, 64 ILLINOIS STATE GEOLOGICAL SURVEY REPORT OF INVESTIGATIONS NO. 77 1941 LIBRARY ENVIRONMENTAL PROTECTiCN AGENO^ STATE OF ILLINOIS ^ SPRINGFIELD, ILLINOIS'' •I