REMOTE STORAGE MIDDLE ORDOVECIAN BLACK R. ! VER OSTRACODS FROM A WELL CORE, JACKSON COUNTY. MlCHiGAN Thesis for flu Degree 0‘ M. S. MECFJIGAN STATE UNIVERSITY James B. Zaitzeff 1962 .4-_ LIBRARY Michigan State University _____ . “I— ~ -_. REMOTE STORAGE PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. DATE DUE DATE DUE DATE DUE 2/17 20“ Blue FORN S/DateDueForms_2017.rndd - pgS MIJDLE ORUOVICIAN BLACK RIVER OSTKACOUS FROM A HELL CORE, JACKSON COUNTY, MICHIGAN by James B. Zaitzeff A THESIS Submitted to Michiban State University in partial fultillment of the requirements for the degree of MASTER OF SCIENCE Department of Geology 1962 Q77 7 3 37/ ././ /..-..>.. / C 2.- ABSTRACT MDDIE 0RDOVICIAN BLACK RIVER OSTBACODS FRCM A WELL CORE, JACKSON COUNTY, MICHIGAN by James B. Zaitzeff Ostracods representing thirty-one species distributed among sixteen genera are described from a well core from the Black River Formation of Jackson County, Michigan. Twenty- three species are described as new. Most of the species are distributed among seven zones within the core. A second occurrence of Platytolbina Henningsmoen in North America is noted and many specimens of leperditiids with spines which have been previously thought to be unusual in the family Leperditiidae are observed. 11 ACKNOJLEDGEMEN TS The writer is greatly indebted to Dr. J. E. Smith of the Department of Geolog, Michigan State University, for her assist- ance and constructive criticism, and under whose direction the study was taken. He also expresses his sincere appreciation to Dr. C. E. Prouty, Head of the Department of Geolog, Michigan State Univer- sity, and to Dr. J. H. Fisher, Department of Geology, Michigan State University, other members of the guidance committee, for their critical reading of the manuscript and valuable suggestions. Ihe author is grateful to Dr. R. V. Keeling, of the Museum of Paleontolog, University of Michigan, for his examina- tion and opinion of several specimens of the Isochilinidae. Thanks to D. Moore, former geolog graduate student at Michigan State University for his help during the study. iii mamorcoumms Page INTRODUCTION......................... 1 LOCATIONANDSIRATIGRAPHY................... 3 LI'IHOLOGEIESCRIPTIONOFCORE................. 6 ENVIRONMENT..........................12 ME‘IHODSANDIECHNIQUES....................1h srsmrATIcmscRIPTIONS....................18 'FamilyLeperditiidae.................18 Familylsochilinidae.................l9 FamilyEurychilinidae................38 FamilySingOPSidae.................5h FamflyOepikellidae.................5h FamilyAparchitidae.................S5 FamilyLeperditellidae................57 FamilyKrausellidae.................63 osmconzouas........................65 mnounrnsscamnosmcom................66 SUMMARY68 REFERENCES 0 O O O O O O O O O O O O O O O O O O O O O O O O O 70 'iv TABLES Table Page I. Measurements of specimens of Isochilina 3,11. sp. . . . . 2h II. Measurements of specimens of Isochilina b, n. sp. . . . . 29 III. Measurements of specimens of Isochilina g, n. sp. . . . . 37 IV. Measurements of specimens of Platybolbina. . . . . . . . 52 FIGURES Figure Page 1. Map location of the Peterson-Howard Well No. l . . . . h 2. Generalized section of the Cambrian and ordmcmsySthBOfMiChiganooooooooocoo S mms Page muonormmr...................... 78 PLA‘IEI 79 Emmmnormmn..................... 80 mm]: 81 EXPLANATIONOFPLAIEIII..................... 82 PLAEIII............................ 83 EXPLANATIONOFPLAIEIV..................... 85 PMEIVOOO0.000000000000000000000... 86 vii INTRODUC TION The Black River Group, with the overlying Trenton Group consti- tutes the Mohawkian Series of the Middle Ordovician. The formations of the Black River have their type localities in northwestern New York. They are in ascending order, the Pamelia, Lowville, and Chaumont limestones. North American ostracods of Black River age have been described by T. R. Jones (1858a, 1858b) from Pauquettes Rapids on the Ottawa River, Canada; Ulrich (1890, 1892, 1891;) from Minnesota, Illinois, Wisconsin, Tennessee, Kentucky, and Pennsylvania; Bassler (1919) from Maryland; and by Keeling (1960, 1962) from Bony Falls on the Escanaba River, Delta County, Michigan. Min Din (1950) describes ostracods from the subsurface Middle and Upper Ordovician of Alpena, Ogenaw, Bay and Ingham counties, but reports none from the Black (River Forma- tion at these localities. The present investigation is a study of the ostracod fauna obtained from a It}; inch drill core from the Black River Formation, in Jackson County, Michigan. The purpose being to collect and describe the ostracods present, in order to make a comparison with other ostracod fauna of Black River age, and also to provide a possi- ble basis for future more detailed correlations with the availability of more material. As the Black River rocks of the Southern peninsula are entirely subsurface and undifferentiated, they are herein referred to as the Black River Formation. There is little information available on the character of the ostracod fauna from the Black River Formation of the Southern penin- sula, and thus most comparison must be made on described forms from outcrops in Canada, Northern Michigan, Minnesota, Oklahoma, Kentucky, and the type Black River of New York, or equivalent strata in Europe. The preservation of the ostracod fauna in most cases was very good. The material collected consisted mainly of separate valves embedded in the rock. Only a comparatively small number of free carapaces could be found. Practically all the ostracods found were in limestone; many good specimens were recovered from detrital zones within the lime- stone. Almost none were fmmd associated with shales, except for a small zone of siliceous, badly weathered valves near the base of the Black River. All specimens are deposited in the Paleontological Museum, Department of Geology, Michigan State University, East Lansing, Michigan. ‘ LGJATION AND SEATIC‘RAPHY The drill core in this study is from the Sun Oil Company, Peterson-Howard well #1, located in the N.w.i=, mac}, s.w.%, Sec. 17, T'. 145, R. 3W, Pulaski Township, Jackson County, Michigan. The unit cored is from thO' to 11395 '. See fig. 1. The Black River limestone in the Southern peninsula of Michigan, is of Middle Ordovician age, consisting of those beds younger than Glenwood and older than Trenton. In the Southern peninsula it is entirely subsurface. Litho- logically it is quite similar to the overlying Trenton. Deposition was practically continuous at some localities from Black River into Trenton time, and the division between the two is rather arbitrary, being based on fauna]. changes or lithology in some places. The Black River Formation ranges from 150 to 517 feet in thickness, consisting of a light brown and gray fossiliferous, dense to crystalline lime- stone and dolomite. The limestones and dolomite occurring in differ- ent localities. The basal Black River in some places consists of a fine-grained dark gray to black argillaceous limestone, or of lime- stone and shale. In the Northern peninsula the Black River is between 67 to 86 feet thick, thinning to the north and northeast with the Trenton. It consists of buff to brown, fine-grained crystalline limestone and dolomite with small amounts of gray argillaceous limestone. MICHIGAN It DEPARTMENT OF CONSERVATION 315132.; Map location of the Paternal-Howard Well No. l 9 I r ‘ ,.« I s " f, norm” M"E ‘4!!! SUPER’OR I 1 \ DOMINION or CANADA ' “mm“ Mum ~__/ 3 . 6m“ I. we: I 3”}..\ ““0“"! non ! c o h};~\J m" scuoorcmr I .\ “use“ mac , ' a .0. ° 0; . ! l ( g . I urn-(c .° (rut -, I : { 1—"’-. . p cum.” * I ’ o'u’fi ( is . I i / ' msot: ISLE s“ . ; ' . I l mama: 7 1‘ " o I I I ' e /"/ PO ! mm: orstoo mm I t‘ S mum ‘ ' * / . ' " .' V mm: «no mus“ custom oscooA .Atcoru I . I Q, rumst 1 I ‘ I \ c l ’. y. rsm «mono ssaurtTiscor-nui can rosco a i I l b g ' -' ’ «true * I \ usorr LAM: ascrou cunt oumm z I ' § J’ moon I / J. .. m 4" I octuu utcosra rsmtu mourn : «woo cu \ TUSC w‘“ A woutuur tuner 5‘5"“ I I I mu ours“ was wet I I I ‘E \z 0m“ noun ctmrorr CW“ i V I I . on u .I I ALLEGAI am (now mom Lmi «um .I 37“ :I m M" ”Lanai armour: k\ marinas um CANADA I I" "'9‘ CASS sr BRANCH LsoAu tum: Maillot . JOSEPH L u’ L ‘ Kt '— ''''' I'N'ISTA'N'A' """ .""'""%'N'T°6" --- [p]: I Figure 20 MICHIGAN Queenstown RICHMOND Big Hill Stonington Bills Creek CINC INNATIAN Lamina MAI'SVZITTE Utica EIEN Collingwood BENTON Trenton a MOHAHKIAN BLACK RIVER Black River Glenwood g CEAZIAN St. Peter Northern Peninsula Southern Peninsula fi —-———- # ———-——- CANADIAN Shakapee PRAIRIE New Richmond w CHIEN Oneota HERMANSVTITE Jordan WU Lodi St. Lawrence E LAKE a SUPERIOR Dresbach o g a: MUNISING Eau Claire a) 0 Mt. Simon JACOBSVTITE Jacobsville Generalized Section of the Cambrian and Ordovician Systems of Michigan after Horowitz (1961). LITHOLOGIC DESCRIPTION or CORE The Black River and Lower Ordovician rocks of the Peterson- Howard Well #1, include 292 feet of the beds from thO' to 1392'. me cored unit from h100.0' to h31h.0' comprises a portion of the Black River Formation at this location. The reader is referred to Kirschke (1962) for a complete petrographic analysis of this core. Lithologically the core has significant variations in composition, and thus can be divided into the following units. IIlO0.0' 8' h107.2' Il107.2I - lflll.0' h11100'- hllZOO' hllzoO' - h12705' Limestone, light brown and gray brown. Aphanitic, and with numerous carbonaceous bandings. Few scattered brachiopods at h103.h' and IilOIl.l'. Leperditella tumida zone at 1;th.8' , occurring in cryptocrystalm finely crystalline gray brown limestone. Preservation is good. Limestone, light gray brown, with few carbonaceous partings; cryptocrystalline. Carbonaceous partings becoming more abundant at bottom of unit. Stylo- lites at Iilll.0'. Very few brachiopods occurring in the unit. Limestone, very light gray. Very little carbona- ceous material. Scattered dolomite rhombs occur- ring in a matrix of aphanitic limestone. Occasional calcite stringers and clusters. Some pyrite. Ostracod zone at Illll.5' - hlll.7'. Isochilina 3, no 8pc, ISOChilina 2’ no 8pc, Plat Olfiina 3, no 8pc Most of the valves are well preserved, except for a few which are partially recrystallized. Only single valves observed. Few Tetradium cellulosul. Limestone, gray and brown gray. Cryptocrystalline and aphanitic, with numerous scattered clusters of calcite or dolomite crystals. Arenaceous zones h127.5' h1h2.9' hlh3.6' h1h5.6' " [OJ-1209' - hlh3.6' - h1h5.6' " M7501" abundant. Carbonaceous bandings numerous throughout section. Brachiopods occurring at 1:115.9', hll9.l', M21.0'; otherwise fossil fragments scattered through- out section. Ostracod zone at hll9.3'- h119.6'. Isochilina b, n. sp., Isochilina c, n. sp., Eol rdi- tes, Platy’oolbina a, n. sp., Platyfi E—n.a sp., Platybolbina e, n. sp., Platybolbina h, n. sp., Platybol‘bina sp. Only single valves were observed, mostly oriented with convex side up. Associated with few brachioped fragments. Pressm- tion good. The lithology of this zone is a coarsely detrital limestone in a matrix of medium to coarse sized calcite crystals. Limestone, light brown, grading downward to a brown gray color, aphanitic. Calcite crystals becoming more abundant in this unit; continuing to hl29.0'. Scattered fossil remains throughout the unit. Brachiopods occurring abundantly at h131. 6', h136. 2', h138. 2', hlh0.9'. Bryozoa at hlh0.7. Corals becoming abundant at I4120.2'- h132.0'. Chart nodule, hl3h.3'. Stylolites at I4137.3'. Limestone becomes more carbonaceous at the base of the unit. Limestone, light brown gray; cryptocrystalline. Calcite clusters very abundant. Few scattered pyrite crystals. Few crinoid stems. Limestone, gray and brown gray. Very crypto- crystalline and aphanitic. Carbonaceous filled vertical and horizontal fractures. Unit is very mottled with carbonaceous material. Somewhat argillaceous due to carbonaceous material. No faunal evidence observed. Limestone, gray, aphanitic, with general "birdseye" and banded appearance due to carbonaceous material, becoming cryptocrystalline at places, and with small clusters of calcite crystals in minute dips. From hl7l.0' to h173.2' the unit has more bands rather than "birdseye" structure. Fossiliferous; brachioPOdss ELI-I900” 14173.3” Bryozoa: 14173.3" Iii-59.05 M5h.0'; ostracods, hl?3.9'. Pyrite. Some stylolites. Arenaceous zones abundant. From M52.0' - Irl67.0', limestone becomes more argilla- ceous, and with dolomite partings. h175.h' - M76.0' M76.0' - 10.77.6' 1817706, " 11.18606' Ill-8606' "' 11191405. u9h05' - 13205.0' I4205.0' - h227.0' h227.0' - h228.h' Limestone, gray to light gray-brown; finely crystalline. Dolomite, gray to gray-brown, dense, finely crystalline, some pyrite. Stylolites at hl76.0'. Limestone, gray to light gray-brown; crypto- crystalline with numerous small clusters of calcite or dolomite crystals. Numerous thin and thick carbonaceous banding with pyrite, Ill76.l' - I4183.6'. A sharp change in texture at h183.8' , from a light brown cryptocrystalline limestone to a fine to medium texture, which grades back into a cryptocrystalline limestone at h18h.0'. Some ostracods at h183.8'. The fauna here is confined to the coarser textured limestone, and stops sharply at the change to a cryptocrystalline limestone. Limestone, gray and some brown-gray; aphanitic and cryptocrystalline with some calcite or dolomite crystal clusters; considerable carbona- ceous banding. Some pyrite. Dolomite occurring in thin bands from hl93.6' - hl95.0' . Brachiopod zone at Irl9l.3-.8'. Bryozoa, IIl9O.Il' - I419Il.5'. Limestone, gray and dark brown-gray; dense and cryptocrystalline at places; widespread carbona- ceous banding in thin streaks and stringers, giving a somewhat mottled appearance to the core. Pyrite crystals scattered throughout the unit. Limestone spotted with dolomite and dolomite bands, from 1.19h.8' to lIl97.8' . Brachiopods and brachiopod fragments scattered throughout the section, zones occurring at Ill-95.75 MSW-6'. Limestone, dark gray and dark brown-gray; aphanitic. Widespread silty carbonaceous bandings in thin streaks; core loses its mottled appearance. Arena- ceous and rudaceous zones abundant. Limestone becomes less carbonaceous at base of unit. Fossils not abundant, but scattered throughout the section; brachiopods, Bryozoa, ostracods (recrystalized), and few single Tetradium were observed. Limestone, brown; cryptocrystalline. Scattered stringers and clusters of calcite crystals. Some 1.22MI - h2h8.6' 142,4806' "’ M9201. h29201' ' h29300' h29300" h29700' 1829700. "' l$298.8. h29808' ‘ h2990h' h299oh' - 1003.0' h30300' ' h3oho6' meet-mes: h305.5' - h306.6' vertical carbonaceous filled fractures, otherwise very little carbonaceous banding. Limestone, dark gray to dark brown-gray; aphanitic. Carbonaceous banding throughout. Few stylolites at h235.5'. A carbonaceous limestone nodule 3 in. diameter at h237.0'. Limestone becomes dark brown and cryptocrystalline frm h227.0' to h230.0'. Chart nodule .15 it. at h230.h'. Limestone, dark gray and dark brown-gray; aphanitic and cryptocrystalline, with thin bands of carbona- ceous material scattered throughout section, also with l to 3 in. stringers of medium to fine crystal- line lime stone scattered throughout section. This crystalline limestone has rounded amid grains and shell fragments that are pea-sized. Vuggy at h280.5'. Stylolitic partings at h391.l'. Lime- stone becomes quite sandy at h261.1'. Brachiopod zone at h27l.0'. Dolomite, brown, aphanitic, with alternate bands of lime stone. Dolomite intorbedded with thin stringers of carbonaceous naterial. Few 1-3 inch stringers of crystalline limestone, with rounded sand grains. Section missing Limestone, brown, aphanitic. Dolomite, brown. Limestone, brown, aphanitic. Few thin carbcnaceous partings. Dolomite, brown to gray-broth; fine to medium crystalline. Limestone, brown. Some fossil debris. Dolomite, brown; fine to medium crystalline. 1130606. - 1830708' h30708' ' h3o9oo' h309oo' - h31306' GLENWOOD SHALE h313.6' - 10111.7' 14311107. ‘ ”1605' 1616.9 - h317.1' h31701' ' h32007' h32007' ‘ h326o7' lO Limestone, brown; aphanitic. Dolomite, brown; medium crystalline. Limestone, brown to gray; very fine to crypto- crystalline, with black highly bituminous shaly partings, from paper thin to one-half inch thick; dense. Brachiopods abundant at h311.0' . Ostra- cods abundant at 1012.0', but all are recrystal- lizedo Shale, black, bituminous, grading to gray-green in bottom 8 inches. Scattered large well rounded sand grains, more abundant in top section. Much fossil debris in upper portion of unit. Siliceous brachio- pods and ostracods at 1613.75 also Chitonozoas, and 1%. Conodonts, scolecodonts, and scaly foss ragments were observed. Dolomite, very light gray, almost white; very fine crystalline, with numerous well rounded sand grains. Dolomite, light green; very finely crystalline. Argillaceous, with many rounded frosted large sand grains. Dolomite, very light gray, greenish at places; very finely crystalline, with numerous rounded, frosted sand grains. Concentration of sand grains at h316.0' - 1018.0'. Shale, green to gray-green; brittle, very indurated, with conchoidal fracture. Considerable amount of pyrite crystals. Many sub-rounded large frosted sand grains, a greater concentration in bottom 10 inches. Some quartzite inclusions. Dolomite, very fighthgray; very fine crystalline, from h322.0' - 22. ' . ONEO'RA h326o7' ‘ h33207' h33207' ' hthol' h3hhol' ’ h3h501' h3h501' ' h36700' h36700' ’ h38900' Dolomite, light brown, fine to medimn crystalline; numerous thin-gray—green shaly partings. Pyrite is very abundant, mud cracks at h330.2'. Dolomite, alternating light brown and gray-brown; very fine crystalline; numerous white impure cherty inclusions; sandy; some glauconite. Dolomite, brown; medium crystalline. Few oolite and sand grains. Dolomite, buff and buff-gray, greenish cast at places; fine crystalline. Argillaceous at places. Some white impure cherty material, glauconite, and sand grains. Finkelnb belletura zone, 1L35h.0'-h35h.5'. ass 8 are 8W Dolomite, buff to white, with grayish cast; fine to medium crystalline. Some thin greenish glauconitic inclusions and partings at points. fiBagbonaceous partings at 14373.1' and 1.378.0'to 2.3'. ENVIRONMENT It has been stated that ostracods are well adapted to diverse environmental conditions, and that they will thrive fairly well under conditions that would be adverse for most other invertebrates. ”Most workers on fossil ostracods collect their speciments from calcareous shales and sands, particularly the shale partings in lime- stone sequences." (Benson, 1961). It is interesting to note that practically all of the ostracods collected from this core, occurred in limestone, and were not associated with shaly partings. In areas where the ostracods were abundant, they quickly decreased in abundance with evidence of argillaceous or shaly material. Although some specimens were recovered from sublithographic type limestones, most were found in the more crystalline limestones. If there was a variation of crystallinity within a zone, the specimens were present in the more crystalline areas. » Most of the ostracods found were not commonly associated with mega-fossils. Kirschke (1962), interprets the environment of sedimentation of this core as of a quiet water condition, because of the predominance of the fine microcrystalline limestone. It also appears to the writer that the waters were relatively shallow during this time. The . occur- rence of new zones of arenaceous and rudaceous limestone, would seem to indicate a necessity for a sea shallow enough to transmit increases 12 13 in energy as might be caused by stoma. Tetradium cellulosum (Hall) is present in many areas of the core; a colony is observed at 11131.0'. These also are indicative of shallow warm seas. Kramer (1962) in his analysis of some Silurian limestones for total carbonate, calcite/ dolomite ratio, and clay mineralogy, found that the brown lithologies analyzed are typically dolomite and are ”the 'oxidized' equivalent of the 'dark' lithologies with a slight addition of elastic particles". Much of the limestone in this core is of a brown lithology, and possibly it can be assumed that this limestone is in an oxidized state, indicating a shallowing and thus more oxidizing condition, although a detailed analysis would have to be made to support this. The fossil zone at M83.8' is interesting because of the abrupt termination of the ostracod fauna against a sublithographic limestone. 11118 might be explained from the result of marine attrition of the sediment of part of the zone to micron size; of if the microcrystalline limestone is the result of a biochemical or chemical precipitation, the fauna may have been restricted because of unfavorable environmental conditions during sedimentation. ME'IHODS AND TECHNIQUES 9252 Examination: A preliminary examination of the core was first made to deter- mine the nature of the fossils present. In the examination for micro- fossils, the core was split transversely at regular intervals and examined with a ten power handlens. In addition, the core was exam- ined at shale partings, and at intervals where there were lithologic and textural changes. Also any section of the core containing macro- fossils was observed for a possible association of ostracods. Fossil- iferous sections were set aside for further study. Since a channel slice had been made on the entire limestone section of the core, this proved to be a great help in locating fossils and changes in litholog. By wetting this sliced portion with water, more as well as microfossil evidence in mam‘cases was shown in greater detail. This method in itself is not a sufficient means of examination, as many of the ostracods found were not observed on the sliced section. Methods of; Disaggregation: A number of methods were investigated in the disintegration of samples from the core for the purpose of extracting the microfossils with the best recovery. They are given below, including the degree of success. The shale section occurring at h313.6'-h31h.7' resisted most of 11; 15 the conventional nethods of disaggregation. This was a laminated, black, highly bituminous shale at the top, grading to a gray-green shale at the bottom. The gasoline method was first tried. The sample was heated in an oven at 150 degrees centigrade for about twenty minutes to drive out the interstitial water. After cooling, gasoline was poured over the shale and allowed to stand for half an hour. The gasoline was then decanted and the sample covered with water. The principle involved is that pressure is built up within the interstices of the shale during the displacement of the gasoline by the water, and the result will be a fine mud. The result in this case was negative. Samples of the shale were neuct treated with a potassium hydroxide solution. The shale was boiled in a 20% solution for two hours, but failed to show any signs of breaking up. The concentration was in- creased to a boil. This method was successful only to the point where the shale was easily split parallel to the bedding. The amount of hydrogen peroxide needed was great compared to the quantity of material oxidized. A further procedure was to freeze and thaw the shale. A sample was placed in a container with just enough water to cover it, and allowed to become saturated. It was then frozen and allowed to thaw. his process was repeated several times over a period of days. The shale weakened and broke down into small chips, which were then split apart farther in examination for conodonts, scolecodonts, and ostracods. None of the above methods proved entirely sufficient. Number one fuel oil was substituted for gasoline in the gasoline method. Two min- utes after the water was added to the sample, the shale was forced 16 apart by the displacement of the oil. The disaggregation of the shale was not complete, but gave better results than the previous methods. Similar procedures were taken with the shale at h320.7'- 11322.05 h322.1l'-1;326.7'. This is a brittle, gray-green, slightly calcareous, indurated non-laminated shale. The only successful method was the use of potassium hydroxide. It broke down to a fine sediment after approximately five days in a concentrated solution. There was no fossil evidence observed in this section. As the simple mechanical destruction of limestone is not a favorable ruethod of disaggregation, because of the low recovery in zones of moderate abundance and of larger ostracods, other methods were sought. One method employed was the use of heat, in order to convert the calcium carbonate matrix to calcium oxide. This mthod is recom- mended for fossils of a phosphate or silica content. The rock sample is first heated in an oven to 100 degrees centigrade for one hour to eliminate the water. The sample was then raised to 1,000 degrees centigrade at the rate of four degrees centigrade per minute. This temperature is held for an hour. The oven is then allowed to cool to room temperature and the sample removed. The time involved for this procedure is a little over four hours. Itwas at first thought suc- cessful, but after the ostracods were removed from the matrix in excellent condition, they powdered after a period of twenty-four hours. Another technique used on the limestone, was first to heat the rock sample to 700 degrees centigrade and then quench the rock in water. 17 This softened the rock greatly and in some cases ostracods were discovered that were not noticeable before. The resulting ostracod valves were fractured and weakened. The best results in preparing the ostracodsfor study, was with the use of a Burgess Vibratool. The point of the tool vibrates 7,200 times per minute and easily shatters off small chips of the rock. In practically all cases the ostracods were only partially exposed when the core was split. By applying the sharp point of the Vibratool in the direction of the specimen, most of the matrix was cleared from the valves. In sections of the core where the ostracods seemed to be relatively abundant, the rock was split in sections as thin as possible with a hammer and chisel to expose as many valves as possible, and then cleaned with the tool and sharp needles. The work with the Vibra- tool was done under the binocular microscoPe at magnifications of 121 for the larger specimens, and Box for the smaller ones and close work on the larger. Most of the valves were left in the rock. It can be said that the above methods have limited ranges of application. . All specimens were coated with amonium chloride sublimate for photography. SYSTEMATIC DESCRIPTICN S Phylum ARTHROPODA Class Crustacea Order Leperditicopida Superfamily Leperditacea Family Leperditiidae Jones, 1856 Subfamily leperditdinae Swartz, 19149 Genus Eoleperditia Swartz, 19h9 32 species. -- flaring! fabulites Calrad, 1816 EOLEPERDITIA EABULITES (Conrad) Pl. II, figs. 1h, 17, 18 mains fabulites Conrad, 18113, p. 89; 1881, p. 3h2; 1891 p. 98; Ulrich, 1890, p. 173; 1891;, p. 63h, pl. 143, figs. 10-11;; Bassler and Kellett, 193h, p. 38h. Eoleperditia fabulites (Ccnrad), Swartz, l9h9, p. 318, pl. 66, figs. 1.10; Swain, 1957, p. 5&5. pl. 59, figs. 1, 3, S, 8; Harris, 1957. p. 129, pl. 1, figs 1. ‘Egmggkg. - According to Swartz (l9h9, p. 317), the genus Eoleperdifia is lacking in a posterodorsal swelling in the left valve. Ulrich (1891;) p. 635) states in his description of Lelaerditia fabulites (Calrad) that, ”a low ridge-like thickening along the posterior half of the dorsal margin of the left valve is to be noticed." Several specimens with this type of thickening on the left, but not the 1‘1th valves, are observed here. See Pl. II, figs. 11:, 18. 18 l9 0cou_rren_c_e_. -- This species is abundant in ostracod zone at 11119.55 occurring in'a gray-brown detrital limestone with a coarsely crystalline ca'|.cite matrix. Most of the valves are lying with the convex side up. Associated with Isochilina 2, n. sp., Isochilina g, n. sp., Platytolbina a, n. sp., Platybolbina b, n. sp., and £33.32“ bolbina g, n. op. The species occurs rarely at 11106.95 and h250.0'. Eolepgrditia fabulites zone occurs at h220.6', in a fine to medium crystalline brown limestone, associated with Bryozoa and brachiopods. Rare at h288.0'. ' 2mg. -- Hypotypes, two left valves, nos. 301, 302; one riglt valve,‘no. 303. Family Isochilinidae Swartz, l9h9 subfamily Isochilininae Swartz, 19h? Genus Isochilina Jones, 1858 223 species. -- Isochilina m Jones ISOCHEDIA A, n. sp. Pl. I, figs. 1-6 Description. -- Valve subquadrate in lateral outline. Dorsal margin straight, about eigt-tenths of shell length, Cardinal angles obtuse. Anterior corner slightly projected, earlike, the posterior corner terminating in a very short spine. Ventral margin gently convex; posterior margin broadly rounded; anterior margin more narrowly rounded and extended medially, concave below the anterior corner. Ealves moderately convex, becaning compressed in central anterior area. Greatest heiglt posterior; greatest width including spine posterior; greatest width, excluding spine, slightly anterior to midlength. 20 Eye tubercle distinct, located about two-tenths the height below the dorsal margn, and about three-tenths the length frm the anterior marm. Large ovate adductor muscle scar lies anterior of midlength and posterior and ventral to eye tubercle; consisting of fine puncta and faint venose lines radiating frm the center to the periphery. Just below the eye tubercle a chevron-V muscle scar is visible when the valve is imersed in alcohol; a node lies near the anterior cardinal corner between the anterior extremity of the hinge and the eye tubercle. A broad, shallow, but distinct sulcus located at the midlength of the valve, and just posterior of the muscle scar, extending ven- trally fran the dorsal margin nearly to the center of the valve. Posterior margin of valve with a flange, which narrows ventrally and continues along the ventral margin as a very narrow rim, reach- ing to below the nndheight of the anterior margin; flange widest at posterodorsal area, and extends a short distance along theposterior hinge area. In the anteroventral area of each valve a distinct inflation is present, its front margin rounded and confluent with the lateral surface, its ventral margin sligltly overhanging the free edge; a second much smaller inflation is located just anterior to and sligltly more dorsal than the first. A broad flange-like spine is located posterior of the larger posteroventral inflation, extending fran the central ventral area, projecting downward and bending slightly obliquely outward, the apex extending beyond the ventral margin and curving toward the posterior. Base of spine flaring and tangent to lateral surface of the valve; its anterior border more dorsal (n the lateral surface of the valve than the posterior border, mahng the spine slightly oblique to the hinge. Spine hollow, tip small and pointed, projecting back sliwtly farther thm the point of tangency of its posterior border on the lateral surface. Surface of valve coarsely and finely punctate. Fran the adductor muscle soar radiating posteriorly and onto the surface of the spine, slightly elevated brmching venose lines, strongest proximally anterior and ventral to the muscle scar, and diminishing in expres- sim posteriorly. Hingement and internal features unlmown. length of holotype, a right valve, 7.25 mun, height h.12 mm. Remarks/Relationships. -- Because of the absence of any noticeable overlap, and the presence of a marginal rim, this species is asdgled to the genus Isochilina Jones. Other leperditiid ostracods with a large spine in the Superfamily Leperditacea, are Isochilig m (Walcott), Isochilina 2, n. sp., Her-mannina ehlersi Keeling, and Eoleperditia? Eglexa Harris. In position of the ventral. spine, Isochilina a, n. sp., is closest to _l_:. m while the spines of g. ehlersi and g? perplexa are more subnedian in position. The general outline, convexity, and marginal flange are similar to that of Isochilina g, n. sp., though that species lacks the large backward curving spine. Swartz (1936) established the family Acrmotellidae to include I'saall straight-backed, generally unisulcate ostracods, with a stralg laterally projecting spine or flange in the lower part of each valve." He also goes on to say the "because of the persistence of the ventral- projections in a considerable number of species, these structures 22 seem to have considerable genetic significance." Teichert (1937) points out that the genera placed in this family widely differ from one another in nearly every other respect, and thus he states it would be rather difficult to follow Swartz when he ascribes "considerable genetic significance" to the ventral projections. Teichert feels that it is more reasonable to assume that the genera in this family are derived from different stocks, rather than representing a natural assemblage of genetically related forms. Teichert cites Leperditia tuberculata (Kolm0din) in support of this idea. L. tuberculata is a large species, typical of Leperditia in size, form, eye and muscle spot, but differs in having a laterally projecting ventral spine. Following Swartz, then, Teichert states that this species should be made the type of another genus, and thus adding another dissimilar genus to the family Acronotellidae. ”Another large species with a ventral though downward directed, projection is Isochilina M (Waleott) Leperditia (Isochilina) m 1883 , which is not a typical Isochilina nor is it congeneric with 1;. tuberculata.” According to the above statements, then this species should also he made the type of a new genus. Teichert further states that Ruedemann's Isochilina M (Waleott) var. meg, ”seems not to be related to Isochilina m, which does not belong to the genus Isochilina Jones.” The writer agrees with Teichert in that Ruedemann's variety W is not related to I. m, and is probably related to Monocerafilia'. as he suggests. The writer feels though, that I. 5% should be retained in the genus Isochilina on the basis of new forms present here. Isochilina _b, n. 8p. as here described appears to be closely related to I. 23 armata in shape, outline, and position and form of the ventral spine. though the development of terminal borders in most specimens of isochflina b, as the typical Isochilinae possess, are not present, this form is indeed generically related to the new'spedies Isochilina g, which possess at least posterior and ventral borders in all spedmns. Possibly these two forms, Isochilina 2, and Isochilina _13, exhibit evolutionary states. 1116 writer feels that in these cases, the presence or absence of appreciable overlap is a more important consideration that marginal. rims. None of the specimens present show any appreciable overlap. Other large forms with laterally spines are Hermannina ehlersi Keeling and Eoleperditia? perplexa Harris. Kesling has stated, (personal communicatim) ,' that when he described 11. ehlersi, that he did not feel the presence of the spine in this form was signifi- cant enougl to create a new genus m this basis. He also felt that the new forms Isochilina _a_, and Isochilina 3 should best be retained in the same genus as l. m (Waleott), and the spine did not warrant the establishment of a new genus. The writer agrees with Keeling in these respects, and also with Teichert in that the ventral or lateral spine is a recurrent homeomorphic feature, rather than of considerable genetic significance. Occurence. -- Isochilina a, n. sp., zone at h111.5' - hlll.7', occurring in a fine crystalline very light-lgray limestone with a background of tiny dolouxite crystalls. Preservation is good except for some forms which are partially recrystallized. Associated with Isochilina g, n. sp., Platybolbina g, n. sp., and Tetradium cellulosum. Rare at 1.129.7'. ' 2h Table I Measurements of Specimens of Isochilina a No. ans. inHmms. DM % ' 9% Remarks *211 7.25 h.12 5 .91. .57 .82 R.v. 212 7.00 3.87 5.75 .55 .82 3.17. 215 6.50 3.62 .56 R.V. 218 5.37 3.12 11.25 .58 .79 R.V. 223 7.00 h.06 5.62 .58 .80 L.V. 219 6.37 3.62 .57 L17. 213 6.25 3.37 5.25 .5h .8h MI. 220 6.12 3.37 5 .12 .55 .8h L. v. 222 5 .25 3.00 h.12 .57 .79 L.V. 2114 5.12 2.87 3.81 .56 .71; MI. 221 5.00 2.68 3.87 .5h .78 L.v. 217 h.87 3.00 3.62 .62 .71; L.v. 216 11.37 2.62 3.56 .60 .81 L.v. 22h h.62 2.62 3.62 .57 .78 R.V. Mean .57 .80 41- Holotype L peatest length H greatest height DH length of dorsal margin 25 m. -- Holotype, a right valve, no. 211. Paratypes, four right valves, nos. 212, 215, 218, and 22h; nine left valves, nos. 213, 211;, 216, 217, 219, 220, 221, 222, and 223. ISOCHILINA B, n. sp. P1. I £188. 7.13, 15 Description. -- Valve subquadrade, subovate in lateral outline. Greatest heiglt posterior. Hinge margin straigit, about three-fourths of valve length. Cardinal angles obtuse. The anterior corner ear- like; posterior corner terminates as a short Spine. Posterior margin broadly rounded and extended ventrally; anterior margin more narrowly rounded and extended medially, and with a broad cmcavity below the cardinal angle; ventral margin gently convex. Valves very gently convex, becoming slightly canpnessed anteranedially. Greatest width, including spine, posterior; greatest width, excluding spine, anterior to midlength. Eye tubercle distinct, pointed, located about one-fifth the heiglt from the dorsal margin, and about cue-fourth the length fran the anterior extremity. Below eye tubercle a chevron-V muscle scar is visible when the valve“ is imersed in alcohol. A very shallow broad depression lies posterior to eye tubercle, extending faintly to the dorsal marm. A low swelling posterior to the depressial booming confluent with lateral surface in posterior direction. A large subouate weakly defined muscle scar lies anterior of the middle and just posteroventral of the eye tubercle; anterior margin of muscle spot in line with the anterior margin of the spine. A small node is located near the anterodorsal corner between the anterior extremity of the hinge and the eye tubercle. Posterior harm of valve with a weakly defined flange, which becomes obscure 26 nddventrally. A large spine extending from the point of greatest convexity in the central. ventral area, extending ventrally and curving slightly outward, and directed posteriorly, the apex projecting beyond the ventral margin in lateral view; fruit border of spine more dorsal on the lateral surface than the rear; spine pointed, hollow, base elliptical in cross section. Lateral surface of valve, and spine punctate; puncta coarsest around peripheral areas. Hingement and internal features uhknown. length of holotype, a left valve, 7.33 mm., height 14.13 mm. Remarks/Relationships. -- This species is close to Isochilina m (Waleott) from the Birdseye and Black River limestmes of Herkimer County, New York, in lateral outline of the valve and in position and shape of the midventral spine. This species differs ’ fran ;. m in not having the anterior and posterior hinge extremities curving upward. This species also has a low dorsal swelling, a node in the anterior dorsal corner. Furthermore some specimens possess a posterior flange and sulcus, not observed in _ i- snar- Paratype no. 118, a left valve, shows a slight overlap by the rimt valve along the ventral margin. In some specimcns variations are found to exist in the relative size of the anterior node and the degree in size of the posterodorsal swelling. Those with a slightly larger swelling tend to accentuate a shallow sulcus posterior to the eye tubercle. One specimen shows a small anterventral inflation, much smaller than that of Isochilina a, 27 n. sp., which is farther anterior on the ventral margin than that of Isochilina a. In many specimens the posterior marginal rim is not observed. This species differs from Isochilina a, n. sp., in not pos- sessing an anteroventral inflation; it does not have the distinct venose lines radiating from the muscle scar observed in all specimens of Isochilina _a, n. sp.; the spine of Isochilina a, is more flat and flange-like; the posterior marginal flange of Isochilina _a, is dis- tinct in all specimens and it widens as it approaches the posterior cardinal corner; the sulcus, when present in Isochilina 2, is anterior of the midlength, and not medial as in Isochilina .5; the valves of Isochilina b are less, and more gently convex than those of the other species. Swain (1957) describes the genus Heterochilina (Poulsen; 1937) as I'I.eperditinae with an area of swelling or a narrow ridge near and subparallel to ventral margin typically anteroventral." He then places Isochilina M (Walcott) flth this genus because of the ”pronounced long midventral spine." ' Poulsen's original description of his genus is as follows: ”The valves are very unequal; the left valve is similar to that of leperdiuo Renault; the rigit valve on the other hand has a quite unique shape, being moderately convex posteriorly and greatly swollen anteroventrally, culminating in a broad rounded ridge, which rises gradually near the ventral margn and extends obliquely upward toward the anterior alarm.” The writer has’not seen the holotype of Isochilina arm__a_t_a_ nor 28 the type species of Heterochilina, but on the available descriptions of these foms, disagrees with Swain's placement of .1. arm__a_ta in the genus Heterochilina. Isochilina _a and Isochilina b as here described appear to be subequi.valved, and the ventral marginal ridge or spine are present in both valves, furthermore the left valve is not similar to Leperditia Rouault. For these reasons this species which is closely related to l. armata (Waleott), cannot be placed in the genus Heterochilina (Poulsen). Occurrence.-- Abundant in ostracod zone at lill9.5', in a gray-brown detrital limestone with a coarsely crystalline calcite matrix. Associated with Eoleperditia fabulites (Conrad), Isochilina _c, n. sp., Platybolbina a, n. sp., Platybolbina b, n. sp., and Platzbolbina _c_, n. sp. Abundant at hl32.h' in a gray-brown limestone, associated with Platybolbina sp. and brachiopods. Occurring rarely between 14102.0' - h12h.8'. m. - Holotype, a left valve, no. 113. Paratypes, five right valves, nos. 1.12, 120, 123, 121:, and 125; five left valves, nos. 111, 113, ILlJl, H8, and 132. ISOCHILINA C, n. sp. P1. 11, fig. 6 Description. -- Valve subquadrate in lateral outline. Greatest height posterior to midlength. Hinge line straight, about three- fifths of valve length. Cardinal angles obtuse. interior cardinal corner acuminate and ear-like. Ventral margin gently curved; posterior margin broad, regularly rounded, extended slightly ventrally; anterior margin more narrowly rounded and extended medially. Greatest convexity Table II Measurements of Specimens of ISOChilina b No. L H DM H DM Remarks in mms. in mms. in mms. I: '1: 125 8.60 h.80 6.93 .56 .81 R.V. 13h 8.07 h.53 6.53 .56 .81 R. v. 133 7.07 14.13 5.60 .58 .79 R.V. 128 6.33 3.73 14.93 .59 .78 R.V. 112 5.20 2.93 h.27 2.56 .82 R.V. 12h h.6h 2.53 3.1;? .55 .75 R.V. 120 14.53 2.1a 3.h7 .5h .76 R.V. 123 into 2.11; 3.147 .55 .79 R.V. 126 h.27 2.33 3 .33 .55 .78 R.V. 129 3.87 2.20 3.00 .57 .78 R.V. *113 7.33 11.13 S .73 .56 L.V. 111: 7.07 3.87 5.73 .55 .81 L.V. 111 6.93 3.87 5.87 .56 .85 L.V. 118 6.93 h.00 5 .73 .58 .83 L.V. 121 6.00 3.33 .56 132 h.80 2.60 3.87 .51 .81 L.V. 122 h.67 2.53 .51. L.V. 116 1.1.0 2.h0 3.60 .55 .82 L.V. 131 h.20 2.29 3.27 .55 .78 115 3.73 2.18 3.07 .57 .82 L.V. ll? 3.33 1.87 2.53 .56 .76 L.V. 130 3.22 1.87 2.53 .58 .79 L.V. 119 3.1.0 1.8h 2.80 .5h .81 L.V. Hem .56 .80 * Holotype L Greatest length H Greatest height DM Length of dorsal margin 29 30 anterior and slightly below the midheight of the valve. Eye tubercle distinct, located about one-sixth the height from the dorsum, and about one-third the length from the anterior extremity. Muscle scar ovate, weakly defined, lying postventral to eye tubercle; posterior to eye tubercle and above the muscle spot, the area is slightly depressed, widening near the dorsum. Posterior margin bordered by a narrow flange, which narrows and continues along the ventral maran as a rim; flange increases sligltly in width at the posterior cardinal corner, and continues along the dorsum to approodmately the midlength of the valve; flange not observed at anterior margin. In the nidventral area a short low posteriorly directed spine- liloe ridge, subparallel to the ventral margin emerges from the lateral surface; ridge becomes smoothly confluent with vflve surface slightly anterior to midlength of the valve, and terminates rather abruptly posteriorly. Surface of valve with coarse puncta. Length of holotype, a left valve, 3.87 mm, height 2.3).; nun. Hingement and internal features unknown. Remarks/Relationships. - This species is like Isochilina a, n. sp. in lateral outline and posterior marfinal flange, but does not have the much larger backward curving nidventral spine. HeterW kentuoflnsis (Ulrich), has a midventral ridge similar to this species, but is less subquadrate in lateral outline, and lacks the posterior marginal flange. Occurrence. -- Rare in Isochilina a, n. sp. zme at hlll.0', also occurring rarely at 141114.0', and in ostracod zme at 14119.0'. 31 m. -- Holotype, a left valve, no. 611. Paratypes, two right valves, nos. 612 and 613. ISOCHILINA D, n. sp. P1. I, figs. 16, 17 Description. -- Valve subquadrate to subovate in lateral view. Greatest height posterior. Hinge margin straight, about three-fifths of valve length. Cardinal angles obtuse. Anterior and posterior cardinal comers terminate in short spine-like projections, the anterior ear-like. Ventral margin gently convex; anterior margin evenly rounded, with a sliglt concavity just ventral of cardinal corner; posterior margin more broadly rounded. Greatest thickness posterior of midlength and near the ventral margin. Eye tubercle distinct, located about ale-fourth the height fran the dorsal margin, and about one-third the length from the anterior extremity. Below eye tubercle is a chevrm-V muscle mark visible when the specimen is immersed in alcohol. A subovate, smooth, slightly elevated adductor muscle scar lies just postventral of eye tubercle. A fine rim extends along the free margins of the valve. A stubby, spine-like pruinence terminating in a point rises midventrally m the lateral surface of the valve at the point of higlest cmvexity; spine inclined slightly ventral, but not over- hanging the ventral margin; anterior border of praninence is slightly more dorsal m the lateral surface than the posterior; posterior margin of prominence concave. Surface of valve punctate, coarser and more dense (n the marginal areas thm m the cen tral area. Hingement and internal features unknown. 32 length of holotype, a right valve, h.25mm., height 2.62 m. Remarks/Relationships. -- This species differs from the other spined forms described here in having a more subdued nidventral prominence which does not overhang the ventral margin. In lateral outline this species is closely similar to Isochilina f, n. sp., but the area of greatest convexity is farther posterior than in that form. Occurrence.-- Rare at 14183.8', occurring in a gray-brown fine crystalline limestone. Associated with Isochilina .13., n. sp., Isochilina 3., n. sp., Platzbolbina _c_, n. sp. and Krausella arcuata. Meg. -- Holotype, a right valve, no. 71.1. Paratype, a left valve,.no. 712. ’ ISOCI-IIIJNA E, n. 81:). P1. II, figs. 7, 8 Description. -- Valve subrectmgular in lateral view. Greatest heiglt central. Axis almcst parallel to dorsal margin. Hinge margin straiglt, about three-fourths of valve length, the extremities terminating in short spine-like projections. Cardinal angles obtuse. Ventral margin very gently convex; posterior margin broadly rounded, and extended medially; anterior margin more narrowly rounded and extended medially, and in some specimens slightly subtruncate dorsally. Valves greatly convex; area of highest convexity anteroventral of middle, where the lateral surface of the valve is greatly tumid, the smut being a small rounded area almost becauigg a point. In anterior view, the dorsal slope frm the point of higlest convexity changes angle of inclination before reaching ‘dorsmn; ventrally the lateral surface descends steeply to the ventral margin. In the left 33 valve , but not the right, the anterior and midventral surface of the valve sliwtly flares smoothly outward just before reaching the free edge, producing a narrow flange-like rim; posterior margin without rim. Riglt valve not flaring at free edge, but with a tiny ridge along the anterior margin which fails midventrally. Eye tubercle distinct, pointed, located about one-sixth the height fran the dorsum, and about one-third the length fraa the anterior extremity. Muscle spot small, round, very weakly defined externally, located quite a distance posteroventral of the eye tubercle. A shallow depression is located posterior and dorsal of the eye tubercle. Surface of valve very finely punctate. Hingement and internal features unknown. Length of holotype, a riglt valve, S.OOmm., height 2.87 mm. Remarks/Relationships. -- 'Ihis species is similar to Leperditia 2121.3 (Blush) in its greatly tamid ventral reglm, abrupt descent of the lateral surface to the ventral free edge, and the depression posterior to the eye tubercle. It differs fran _1_:. 513211 in having the area of greatest convexity anteroventral to the middle, rather than near the center. Furthermore Isochilina _c_, n. sp., is of smaller size, the axis is nearly parallel to the hinge and it differs in the outline of the ventral edge. Occurrence. -- Relatively abundant at h180.2', in a crypto- crystalline chocolate-brown colored limestone. 32233. -- Holotype, a right valve with posterior cardinal corner broken, no. 811. Paratypes, one broken riglt valve, no. 812; two left valves, nos. 813, broken, and no. 811; an immature valve. 3h ISOCHIIJNA F n. sp. Pl. I, figs. 11;, 18, 19 Escription. -- Valve subquadrate, subovate in lateral view. Hinge margin straight, about seven-tenths of valve length, with approximately equal obtuse cardinal angles. Anterior margin regu- larly rounded and extended medially; posterior margn more broadly rounded and fullest slightly below midheight of valve. Greatest calvexity slightly anterior of midlength and anteroventral on the valve surface, from the summit of which, the surface descends with a gently concave slope to the dorsal border; ventrally surface descends with a slightly convex curve and with a steep inclination to the ventral margin, where the edge of the valve curves inward producing a narrowly rounded or beveled edge; slope to the anterior and posterior is in a less convex curving slope. Internal margin of right valves fith a groove. Left valves with a fine ridge along the ventral edge. . Eye tubercle weak, located about one-fifth the heiglt from the dorsal margin, and about one-third the length from the anterior edge; a short low ridge parallel to the dorsum is located just below the eye tubercle, which terminates at the anterior edge of the muscle scar. Muscle scar large, round, smooth, slightly elevated, weakly defined externally, located just posterior to the eye tubercle; top border of muscle scar reaching about as far dorsally as the dorsal margin of the eye tubercle. Surface of valve punctate in peripheral regions. Hingement and internal features unknown. Length of holotype, a riwt valve, h.75 mm., height 3.00 mm. 35 Remarks/Relationships. -- If the ridge of the left valve fits into the groove of the right on closure, the overlap in this species is very slight, as compared with that of the typical Leperditiinae. lherefore this species probably belongs to the genus Isochilina. I Occurrence. -- Comma: at 14183.8' in ostracod zone. m. -- Holotype, a right valve, no. 911. Paratypes, four left valves, nos. 912, 913, 9114, and 915; one right valve no. 916. 1300mm 6, n. sp. Pl. II, figs. 1-5 Description. - Valve subovate in lateral outline. Greatest heiglt just posterior of midlength. Hinge margin short, about three- fifths of valve length, with well defined obtuse cardinal angles ; ulterior cardinal angle much less obtuse than the posterior. Anterior cardinal corner ear-like. Ratio of length of dorsal margin to height is apprmimately one to one. Ventral margin of right valve more convex than that of the left, dropping slightly ventral to the free edge midventrally, and overlapping the left valve almg a short area m the ventral margin; anterior margin broadly rounded, extended medially; posterior margin more narrowly rounded, extended medially about two and ale-half times as far beyond the limits of the hinge as the anterior margin. Point of greatest convexity sliwtly anterior to midlength. interior and posterior margins with narrow flanges which extend a short distance along dorsum beyond the cardinal corners; flanges fail ventrally, becoming groove-like as they approach the midventral area; flanges not flat, but moderately sloped towards the edge of the valve, the anterior less wide than the posterior. 36 Eye tubercle distinct, pointed, located about one-third the length from the anterior extremity, and about one-sixth the height from the dorsum; ventral to the eye tubercle is a chevron-V muscle mark that is faintly visible when the valve is immersed in alcohol. Adductor muscle scar subovate, slightly elevated, and weakly defined, lies posteroventral of eye tubercle. A very shallow depression lies dorsal to the muscle scar and fades obscurely into the dorsum. Hinge finely denticulate, at least posteriorly. Surface of valve very finely punctate. Internal features unknown. Length of holotype, a right valve, 11.13 111111., height 2.53 mm. Remarks/Relationshipg. -- Isochilina columbina Bassler and and L_eperditia gregaria Kiesow, have a short hinge comparable to Isochilina g, n. sp. The cardinal angles of I. columbina are much more obtuse than those of this species, and the eye spot in the former is much closer to the dorsum. Furthermore Isochilina 5 does not have the pronounced swing to posterior as shown in the taro species. Paratype no. 1112 shows faint venose lines radiating from the muscle scar. Occurrence. -- Common at h281.0' in a very light-gray crypto- crystalline limestone. Rare at 11111.0' in Isochilina a zone. meg. -- Holotype, a right valve, no. M9. Paratypes, twelve right valves nos. 1.1.1, an, 1.13, 1116, 1.17, 1.20, 123, 1.21., 121..., 1121lb, 1125, and 1&7; six left valves nos. 11114, 1115, 1118, h21, h22, and h26. Table III Measurements of Specimens of Isochilina g, n. sp. No. L H m H m m Remarks in mm. in mm. in mm. L. T —H' 1123 5.1;? 3.20 .59 R.v. 1121: 11.91 2.97 .61 RN. 32¢ 11.53 2.86 2:23 .62 .60 .98 £1.17. h20 11.27 2.67 2.53 .63 .59 .95 R.V. *h19 11.13 2.53 2.110 .61 .58 .95 R.V. 1112 3.1;? 2.17 2.13 .63 .62 .98 R.V. 1116 3.33 1.89 2.07 .57 .62 1.09 11.7. 1117 3.2h 2.07 2.10 .61; .65 1.00 R.V. 1113 3.13 2.07 1.87 .66 .60 .90 R.V. h2hb 2.67 1.71 .611 R.V. 11253. 2.110 1.60 1.33 .67. .61 .92 R.V. 1.11 2.13 1.117 1.33 .69 .63 .91 R.V. 1125 1.87 1.29 1.28 .69 £1.17. MS 5.80 3.1a 3.33 .60 .57 > .96 L.V. 1122 5.117 3.07 .56 L.V. 1:26 11.96 2.93 2.67 .59 .5h .91 L.V. 1121 3.92 2.20 2.33 .56 .60 1.06 L.V. 1118 3.27 2.00 2.00 .61. .61 1.00 L.V. 1.114 2.97 1.89 .614 L.V. Mean .62 .61 .97 «- Holotype L Greatest length H Geeatest height HM Length of dorsal margin 37 38 Order PalaeocOpida Suborder Beyrichicopina Superfamily Hollinacea Family Eurychilinidae Ulrich and Bassler, 1923 Genus Eugghilina Ulrich, 1889 me species. -- Eurychilina reticulata Ulrich, 1889 EURYCHILmA A, n. Sp. Pl. IV, figs. 26, 27 QLscription. -- Valve medium to large; subovate to subquadrate in lateral outline. Hinge line long and straight, with approximately equal cardinal angles. Ventral margin slightly curved, and with a slight forward swing; anterior margin more broadly rounded than posterior. Valve moderately convex. Anterodorsal sulcus, deep, extending from dorsum to approximately one-half the height of the domicilium; anterior margin of sulcus steep; posteroventral margin of sulcus gently sloping; ventrally sulcus is bordered by a very fine low ridge; an elongate node forms the anterior margin of the sulcus. A fine groove is present on the ventral lateral surface of the domicilium, paralleling the ventral margin, and then curving upward anteriorly and posteriorly, terminating at the cardinal angles. Surface of domicilium above groove finely granular, and with sparsely scattered pits. Frill convex, becoming flatter posteroventrally, flaring post- eriorly; frill with widely spaced radial striae and continuous con- centric elements. Hingement and internal features unknown. 39 Length of holotype, a left valve, 1.70 mm., height, including frill,.98 mm. Remarks/Relationships. -- A few species are somewhat similar to this form. Eurychilina pu_nctata Teichert, from the Wright Bay Formation of northern Greenland is quite similar in lateral outline, convexity and forward swing. The surface of the valve of that species has mall pits, and the dorsal slope with low tubercles. This species differs from E. punctate., in not having a. curved lobe at the ventral half of the sulcus; it has a granular rather than low tuberculata surface and a curved ventral groove on the lateral surface. This species also has continuous concentric elements on the frill. Emhilina reticulata and E. subradiata Ulrich are of similar form, but E. reticulata has a reticulata surface, and 15. subradiata has a much stronger tubercle adjacent to the sulcus, and an abruptly elevated ridge in the posterior half. Occurrence. -- Fairly common in ostracod zone at h290.3'. mg. -- Holotype, a left valve no. 1001. Paratype, a right valve no. 1002. Genus Euprimitia Ulrich and Bassler, 1923 Me specie . -- Primitia sanctipauli Ulrich, 1923 EUPRIMITIA LABIOSA (Ulrich) Haliella labiosa Ulrich, 18911, p. 656, pl. 116, figs. 113-116; Harris, 1931, p. 92; 1957. p. 200. p1. 6. figs. 1h. 15. 1681-23 Kay. 19314. pp. 329, 332-3311, p1. 11;, figs. 17, 18. Euprimitia labiosa (Ulrich) Kay, 19110, p. 252, pl. 31, figs. 16-18. Occurrence. -- Rare in ostracod zone at h290.3'. meg. -- Hypotype, one left valve no. 21101. 140 EUPRIMITIA? A, n. sp. Pl. IV, figs. 111-l6 Descrifiion. -- Valve subquadrate, elongate in lateral view. Dorsal margin straight and long, with well defined obtuse cardinal angles, the posterior less obtuse than the anterior. Posterior margin more broadly rounded than the anterior. Greatest height and width posterior. 82 located anterior to midlength, deep, narrow, slightly oblique to dorsum; anterior to sulcus. L2 is a smooth subtriangular area, narrower at the top; 81 obscurely defined. A narrow ridge, on the ventral lateral surface parallels the edge of the valve; posteriorly the ridge merges with the free edge at approximately the midheight of the valve; anteriorly the ridge does not merge with the free edge, but fades into the lateral surface of the valve below the midheight of the valve; ventrally the ridge nearly obscures the free edge of the valve. Free edge slightly more pro- tuberant at the posterior and ventral areas; area within the Elevated ridge and the free edge forms a wide shallow channel. Lateral surface of valve with distinct low linear ridges. Length of holotype, a left valve, .71 11111., height .1111 mm. Hingement and internal features unknown. Remarks/Relationships. -- The generic status of this species is questioned because the valve surface is characterized by linear ridges rather than a reticulate ornamentation as Euprimitia. It is similar to the genus in size, lateral outline, straight narrow sulcus, presulcate node, and elevated ridge along the free margins. Toe dis- tinctive ornamentation distinguishes this species from others of the gmus s Occurrence. -- Fairly common in ostracod zone at h290.0'. 3mg. -- Holotype, a left valve, no. 1101. Paratype, two left valves, nos. 1102 and 1103. EUPRmITIA B, n. sp. Pl. IV, fngQ 11-13 Descripticn. -- Valve subquadrate in lateral outline. Hinge line long, with distinct obtuse cardinal angles, the anterior more obtuse than the posterior. Anterior margin more evenly rounded and broader than the posterior. Greatest height anterior; greatest thick- ness posterior; lateral surface of valve descends to the posterior edge in a less convex curved slope than the anterior. 82 located anterior to midlength of valve, pit-like at the base, constricted medially, and flaring dorsally. L2 a small subtriangular area, narrower at the top. Located on the ventral surface of the valve, is a low narrow ridge paralleling the ventral edge, and be- coming confluent with the valve surface as it approaches the anterior and posterior margins. Ventral edge of valve slightly flaring, form- ing a shallow channel between it and the ventral edge. Near the anterior and posterior margin of the valve on the lateral surface, a short groove extends from the dorsum. Surface of valve with a linear reticulation; coarsest in the central area. Length of holotype, a right valve, .514 mm., height .3h mm. Remarks/Relationshigg. -- This species is somewhat similar to @rimitia 2922-2312 (Ulrich). his form differs in having the reticulation in a linear arrangement and in the presence of grooves extending from the dorsum, near the anterior and posterior margins. 1:2 Occurrence. -- Common in ostracod zone at h290.3'. 2229.8: -- Holotype, a right valve, no. 2611. Paratypes, two right valves, nos. 2612 and 2613. EUPRIMITIA, sp. Pl. IV, fig. 9, 10 Description. -- Valve, subovate. Hinge straight. Posterior margin evenly rounded; anterior margin blunt below the cardinal corner, and becoming angulate below; ventral marginal curve uniform from posterior toward the anterior, until it reaches the point at which the greatest height is measured, where it curves more sharply dorsally to the anterior margin. Greatest convexity posteroventral, where the valve is quite inflated. Sulcus located anterior to midlength, deep; dorsal part flaring, and reaching dorsum; a small node lies within the flared area of the sulcus; presulcate area a large elliptical lobe. Surface of valve finely reticulate, and with sparsely scattered papillae; a double row of papillae parallels the ventral margin of the valve. There are two forms present. One possesses a narrow flaring radial striate frill, and the other a narrow ridge paralleling the ventral margin. Length of a female left valve, .514 m, height .314 mm. Remarks/Relationships. -- The narrow radial striate frill, and the large elliptical presulcal node easily distinguish this form. Only one specimen of the frilled form was found. The non-frilled type, which is probably the male, differs from the frilled form in having a smaller presulcal node, and a narrow velate ridge rather than a friJl. Subfamfly Chilobolbininae Jaanusson, 1957 Genus Platybolbina Henningsmoen, 1953 2222 gecies. -- Primitia distans Krause, 1889 PLATIBOLBINA SCEADDJEA Kesling Platy’oolbina schadidea Keeling, 1960, p. 371;, pl. 1, 2, 3, 5, figs. 1-5, 1-8, 1, h, h-7. Occurrence. -- Rare at h290.3'. Associated with Primitiella a, n. sp. and Primitiella?_b_, n. sp. PLATIBOLBDIA A, n. sp. P1. III, figs. 7-10 Description of 9113:. -- Domicilium suquadrate, elongate, with greatest height just posterior cf muscle spot. Anterior margin more broadly rounded than posterior. $2 absent in most valves, but de- veloped as a narrow groove above the muscle spot in a few. L2 not defined. Lateral surface of valve rather uniformly convex. Muscle spot subovate, large, slightly raised above the adjacent surface, delineated by fine pits; top of muscle spot attenuated as a fine low ridge. Corner areas confluent with dorsal plica, a narrow rounded ridge; extremities of plica turned down, the anterior corner more abrupt and larger than the posterior. Surface of domicilium with a fine, even reticulation. A row of tiny tubercles parallels the ven - tral margin of the domicilium. A short shallow groove is located ventrally on the domicilium, between the muscle spot and row of tubercles. 6 Frill relatively narrow, abuut one-fourth the height of the domicilium; with narrow peripheral rim; ventral part flaring, con- cave, flattening gradually as it approaches the anterior cardinal 11h corner. Anteriorly frill gradually tapers to just below the car- dinal corner; posteriorly at just below the midheight of the domi- cilium, frill tapers more abruptly and continues to the posterior cardinal corner as a low, narrow velate ridge. Frill radially striate, and with distinct continuous concentric elements. Hingement and internal features unknown. Holotype, a right male valve, 1.09 mm., height .65 mm. Remarks/Relationships. -- All specimens found appear to be males. Platybolbina dicilota Keeling, has a fine even reticulation and a dorsal plica, but this species differs in having a smaller anterior comer area, distinct concentric elements and a peripheral rim on the frill. The greatest height in this species is slightly posterior, rather than anterior as in 1:. dictzota. a. flhalota Keeling also has a fine reticulation, but is easily distinguished from this species by its lacriform muscle spot with sub-central pit. E. Haslovi Sarv and g. m Keeling have a much coarser reticu- lation than does this species; furthermore 2° m lacks the dorsal plica and the frill of g. maslovi terminates in a spine. Occurrence. -- Abundant in ostracod zone at lall9.5'. m. -- Holotype, a right male valve, no. 515. Paratypes, three left male valves, nos. 511, 512, and 516; three male right valves nos. 513, Elk, and 517. mmomnu B, n. sp. Pl. III, figs. 3, 5, 6, 11 Description of female. -- Domicilium subelliptical elongate. Greatest height just posterior of muscle scar. $2 a shallow faint groove above the muscle scar, not reaching dorsum. L2 low and indistinct. Highest convexity posterior of muscle scar. Muscle scar subovate, narrower at the top, lying nearer the ventral than the dorsal margin; delineated by a shallow groove. Anterior corner a raised smooth shoulder; posterior corner turned down, and much less distinct than the other. Ornamentation consisting of raised low tubercles, most dense in the central area; a row of fine tubercles near and parallel the ventral margin of the domicilium. Ventral to the muscle spot and dorsal to the frill, a shallow are- like groove extends posteriorly. Frill broad, about one-half the height of the domicilium, its posterior point of contact slightly higher on the lateral surface of the domicilium than the anterior; ventral and anteroventral part convex; ventrally flaring and gradually flattening as it approaches the anterior dorsal border; anterior margin gradually tapering and ending just below the anterior cardinal corner; posterior ending more abruptly in posteroventral area; posterior margin slightly concave, with a pointed posteroventral termination. Frill with distinct striae and fine concetric elements. Hingement and internal features unknown. Description _o_f r_n_al_§. -- The male of this species is similar in all respects to the female, except it does not have the convex frill of the female. A groove is present on the domicilium ventral to the muscle spot, which is not observed on the female. Length of holotype, a female left valve, 1.25 mm., height .66 mm. Remarks/Relationships. -- The frill of Plamolbina maslovi Sarv ends in a spine but has a coarse. reticulation and no development of an 82 as does this species. 2. distans Krause and 3. Egg Jaanusson 116 have a tuberculate ornamentation, but in this species it seems to be much coarser. Furthermore this species differs from the above two in having a spine-like frill termination. The tuberculate ornamentation is sufficient to distinguish this species from Platybolbina g, n. sp. and Platybolbina 11., n. sp., whose frills also terminate spine-like. mg. -- Holotype, a left female valve no. 523. Paratypes, one right male valve, no. 521; one left male valve no. 522; two female left valves, nos. 525 and 526; three right female valves nos. 52h, 527. and 528. PLATIBOLBDIA c, n. 8p. Pl. III, figs. 1, 2 Description. -- Domicilimn subelliptical. Greatest height posterior. 82 a narrow groove above muscle scar. L2 a high rounded smooth lobe, anteroventral of muscle scar. Muscle scar lacriform, with a shallow pit in the center; delineated by a faint groove which continues in dorsal direction. Corner areas confluent with dorsal plica, a narrow ridge; anterior corner turned ventrally sharply, the posterior less abrupt. Sur- face of domicilium finely reticulata. A short linear groove is located between the muscle spot and frill. Frill broad, about one-half the height of the domicilium, flaring in central ventral part, and flattening as it approaches the anterior cardinal corner ; posterior frill narrows slightly a short distance, and then ends abruptly; the posterior margin concave in lateral view, with a pointed spur-like posteroventral termination. Frill with radial striae and distinct continuous concentric elements. Hingement and internal features unlmown. h? Length of holotype, a left valve, 1.30 mm., height .75 mm. Remarks/Relationships. -- This species is easily distinguished by its lacriform muscle spot with central pit, the large S and post- 2, eroventral spur-like frill termination. Platybolbina _c_, n. sp. seems closest to Platybolbina o_1_nphalota Kesling in lateral outline, L2, and ornamentation. This species differs in having a shallower reticulation, having the greatest height posterior rather than near the middle, continuous concentric elements on the frill, and a groove between the muscle spot and the frill. The frill of this form is slightly flaring, and not concave as those of the females of the genus. Occurrence. -- Rare at hllh.0'. mg. -- Holotype, a left valve, no. Shl. Paratypes, a left valve,'no. 5112. PLATYBOLBINA E, 11. SP. Pl. III, figs. 12-15, Pl. IV, fig. 30 Description 93 9313. -- Domicilium subquadrate. Greatest height just posterior of muscle spot. 82 poorly defined. 1 L2 not defined. Greatest convexity in posterior half of domicilium. Anterior margin more broadly rounded than posterior. Muscle spot large, raised, ovate, located just anterior of the midlength of valve; in some, top of muscle spot attenuated as a fine low ridge; area peripheral to muscle spot slightly depressed. Dorsal plica, a narrow rounded ridge. Corner areas confluent with dorsal plica, the anterior teminus . of plica turned down sharply, the post- erior more smoothly turned, and less prominent. A groove is located below the muscle spot, directed posteriorly, and subparalleling the ventral margin of the domicilium; groove arches upward and terminates slightly below the midheight of the domicilium near the anterior margin. Ornamentation consists of a fine reticulation. 118 Frill about one-fifth the height of the domicilium; with peri- pheral rim; ventral part flaring; anteriorly frill tapers gradually and flattens to the anterior cardinal corner; posteriorly frill is less flaring, and tapers more abruptly to the midheight of the domicilium, and continues to the posterior cardinal corner as a low narrow velate ridge. Frill radially striate, and with fine distinct continuous con- centric elements. Hingement and internal features unknown. Description 23' $331313. -- The frill of the female is convex, and less flaring than that of the male, and the ventral groove is less distinct in the female forms. Length of holotype, a male left valve, 1.15 m, height .73 mm. Rourke/Relationships. -- Platybolbina a, n. sp. is similar to this species in lateral outline and ornamentation. Platybolbina g differs in being much more convex in the posterior half and in the extension of the ventral groove to the midheight of the valve. 2. dictzota Keeling also has a fine, even reticulation, but the new species differs in its posterior convexity and its conspicuous radial striae and concentric elements on the frill not observed in the former species. Occurrence. -- Rare at 14111.5'. Common at hll9.5' in ostracod zone. meg. -- Holotype, a male left valve no. 551. Paratypes, one left male valve, no. 552; one right female valve, no. 562; two left female valves, nos. 561 and 563. 1:9 PLATYBOLBINA x, n. sp. Pl. III, figs. 13, 16, Pl. IV, figs. 28, 29 Description. -- Domicilium subquadrate to subovate. Greatest height just posterior of muscle spot. 32 faintly developed narrow groove above mscle spot. L2 a low rounded area adjacent to muscle spot, faintly reticulata. Muscle spot large, lacriform with a shallow pit; delineated by. a shallow groove. Anterior corner a smooth slightly raised shoulder, posterior corner less distinct. Surface of domicilium with a fine even reticulation and low scattered tubercles. Frill very wide; anteriorly frill tapers gradually to the anterior cardinal corner; posteroventrally frill ends abruptly in a spur-like termination. A sausage-like structure is located on the dorsal part of the frill. Frill radial striate, and with overlying concentric elements, not cnntinuous, but forming a mesh of elongate honeycomb units. Hingement and internal features unknown. Length of holotype, a left valve, 1.143 mm., height . 79 mm. Remarks/Relationships. -- The dimorphism of this species is not established. The frill of the holotype possesses a sausage-like structure on the dorsal part of the frill, rather than being fully convex as those of the females in other species. In some specimens the sausage-like structure is absent, and the develOpment of the L2 is less developed in others. Occurrence. -- Rare at 11202.0', h219.0', and h230.0'. Egg. -- Holotype, a left valve, no. 581. Paratypes, one right valve,no. 571; two left valves, nos. 582, 583. 50 PLATIBOLBINA H, n. sp. Pl. III, figs. 18, 19 Description 33 E2. -- Domicilium subelliptical. Greatest height anterior. $2 a distinct narrow groove above muscle spot, flaring slightly below the dorsum. L2 a small rounded area antero- ventral of muscle spot. Anterior margin more broadly rounded than posterior. Muscle spot lacriform, the dorsal part of which is attenuated as a fine narrow ridge lying in sulcal groove; muscle spot delineated by radial grooves. Anterior corner area turned ventrally abruptly; posterior less pronouncely turned. Lateral surface of domicilium nearly smooth; with sparsely scattered tiny tubercles. Frill narrow, about one-fifth the height of the domicilium; ventral part flaring; anterior margin rounded; posteriorly frill ends abruptly, terminating as a spur-like projection; frill with faint radial striae and concentric elements. Hingement and internal features unknown. Length of holotype, a left male valve, 1.20 mm., height .63 mm. Rourke/Relationships. -- In lateral outline _li. PEEL“ Keeling is similar to this species. It also has a nearly smooth domicilium and a muscle spot delineated by radial grooves as does this form, but Platybolbina h, n. sp. is easily distinguished by the spine-like frill termination. In addition this species has no groove between the muscle spot and frill. g. glint; (Krause) also has a nearly smooth domicilium, but lacks the spine-like frill termination of this species. No females of this species were observed. We. -- Holotype, a left male valve no. 591. Paratype, a left male valve no. 592. 51 PLATIBOLBINA sp. Pl. III, fig. h Description. -- Domicilium subquadrate. Greatest height just posterior of muscle spot. 52 a well defined narrow groove curving anteriorly a short distance. L2 a low, rounded, slightly elevated area adjacent ot the muscle scar. Dorsal plica a narrow rounded ridge. Muscle spot lacriform, with a shallow central pit; outlined by a distinct groove continuing in dorsal direction, becoming confluent with the sulcus. Anterior and posterior corners subcrescent, confluent with dorsal plica. Lateral surface of domicilium smooth; a fine arc-like groove begins at the base of the muscle spot and is directed poster- iorly; dorsally are two very short grooves. A double row of altern- ating fine tubercles parallel the ventral margin of the domicilium. Frill very wide, about two-thirds the height of the domicilium, broad and flaring, tapering and flattening anteriorly, ending just below the anterior cardinal corner; posteriorly frill decreases slightly in width, then terminates bluntly in a spur-like projection. Frill with radial striae, and continuous concentric elements. Length of right valve, 1.30 mm, height .69 mm. Remarks/Relationships. -- Only one specimen of this form is observed here. Although it is probably a mature specimen, it does not exhibit the same features as any described form. The posterior termination of the frill is not complete, but appears to terminate in a spur-like projection. This form appears to be closest to 111g- bolbina g, n. sp. in lateral outline, L2, and muscle epot, but has a smooth domicilium. Measurements of Table IV Specimens of Platybolbina No. Platybolbina Domicilium Frill Remarks species L H width (Ian) (M) 513 Platybolbina a 1.15 .70 .18 R.V. male 511; 1.05 .65 R.V. male *515 1.09 .65 .17 R.V. male 517 1.00 .58 R.V. male 512 1.15 .69 .20 L.V. male 511 1.05 .65 .15 L.V. male 516 1.05 .65 .16 L.V. male 521 P12131261 ina p 1.15 .65 R.V. male 522 1.15 .61; .25 L.V. male 526 1.28 .70 .35 L.V. female *523 1.25 .66 .30 L.V. female 521: 1.15 .61; .29 R.v.ffnmale 525 1.10 .5h .25 L.V. female 527 1.25 .65 R.V. female 528 1.20 .68 R.V. female 529 1.25 .70 530 1.30 .70 L.V. 41-5141 Platl‘golbina g 1.30 .75 .35 L.V. male 512 1.10 .61 L.V. male? 52 Table IV (continued) No. Platybolbina Domicilium Frill Remarks species L H width (nun) (null) *551 Platybolbina g 1.15 .73 .20 L.V. male 552 1.00 .58 L.V. male 562 1.10 .65 .25 R.V. female 563 1.110 082 026 L.V. female 561 l. 20 . 7O .30 LVV. female *591 Platybolbina h l. 20 . 63 . 22 L .V. male 592 1.15 cal» .19 L.V. M19 571 Platybolbina _x_ 1. 50 . 88 . 70 R.V. *531 1.113 .79 .50 L.V. (sausage- . like structure) 582 1.50 . 80 . 60 L .V. (sausage- like structure) 583 , 1030 c 70 L -. v. 58!; Plagzgolhina sp. 1.30 .69 .16 R.V. 585 2° schadidea 1.10 . 61 R.V. male Keeling, 1960 -x- Holotype L Length of domicilium H Height of dodcilium 53 5h Family Sigmoopeidae Hemingsmoen, 1953 Genus Winchellatia Kay, 1910 SEE flecies. -- Uinchellatia loggispina Kay, 1910 WINCHEILATIA LONGISPllVA Kay { wincheliatia longispina Kay, 191.0, p. 25h, pl. 32, figs. 1-5. Remarks. -- This form is like 11. lgngispina Kay, except that it has a reticulate ornamentation. Occurrence. -- Rare in ostracod zone at h290.3'. mg. -- Hypotype, a left valve, no. 2711. Superfamily Oepikellacea Family Oepikellidae Jaanusson, 1957 Genus Oepikella Thorslund, 1910 m E2219 . -- Opikella tvaerensis Thorslund, 191:0 OEPIKELIA A, n. sp. P1. IV, £183. 22-25 Description. -- Valve subovate in lateral outline. Dorsal out- line umbnnate, most prominent in central part. Hinge margin long and straight, channeled. Cardinal margins flattened. Anterior margin evenly and broadly rounded; posterior margin more narrowly rounded and extended above. Greatest height central; greatest thickness posterior and ventral to center of the valve. Muscle spot oval, located slightly anterior and dorsal to the center of the valve; muscle spot surrounded by posteriorly directed vascular markings. Left valve, overlaps right valve along the free edge. Borders of valve depressed, free edges thickened as a beveled edge, which becomes a narrow rounded ridge ventrally. Mface of valve punctate. Internal features unknown. Length of holotype, a right valve, 2.05 mm., height 1.52 mm. Remarks/Relationships. -- The dimorphism of this species is not established here. Only forms with a narrow, rounded ventral ridge were found, which are probably males. No female or frilled forms were observed. This species is somewhat similar to Q. tvarensis Thorslund in lateral outline, muscle spot, and ornamentation. Oemkella a, n. sp. differs in having the posterior margin more narrowly rounded than the anterior, and in having a thickened anterior cardinal corner. Occurrence. -- Abundant at 11,133.0'. 3mg. -- Holotype a right valve, no. 1211. Paratypes two right valves, nos. 1212 and 1213; two left valves, nos. 1211; and 1215. Family Aparchitidae Jones, 1901 Genus Saccelatia Kay, 19140 mg species. -- Aparchites arrectus Ulrich, 18911 ‘ saccnmm mm Levinson Saccelatia kellettae Levinson, 1961, p. 360, pl. 1, figs. la-ld. Remarks. -- Only a single specimen of this species is present. It agrees in all characteristics with the Bromide holotype, but is somewhat larger. It measures 2.0mm, and that of the Bromide holo- type 1.16 m. m. -- Hypotype, a right valve, no. 1611. I Genus Diplgpsis Levinson mg min . -- 12132818 socialis Levinson 1961 DIPLOPSIS? A, n. sp. P1. II, £1.83. 9.13, 15’ 16 Description of female. -- Valve subovate, subtrapezoidal. Hinge 56 short, with obtuse cardinal angles. Anterior and posterior margins subangulate a distance below dorsum; anterior margin below angulation narrowly rounded; posterior margin below angulation blunt. Greatest convexity anteroventral. Surface coarsely punctate, and with smooth area in central ventral region. krill slightly incurved, sloping downward from the contact margin of the valve; ventrally frill retains a constant width, then tapers abruptly to the valve as it nears terminal marginal areas; posterior termination of frill slightly more dorsal than the anterior; frill with widely spaced radial striae. Hingement and internal features unknown. Description of £5.13: -- This form lacks a frill, and is without a velar structure. Puncta, smooth area, and position and shape of greatest convexity is similar to that of the frilled form. In the unfrilled form the anterior and posterior margins are more evenly rounded, and the posterior margin is extended farther beyond the hinge than the anterior. Length of holotype, a female left valve, 3.10 mm., height 2.16 mm. Remarks/Relationships. -- The generic status of this species is questioned, as no ventral marginal ridge is observed on the non-frilled forms as in DiploEsis Levinson. Bullatella Svain & Cornell, has a mid- ventral swelling, a punctate surface with a'smooth. submedial muscle spot, but it also has a ridge adjacent to the free margin of the valves. Diplopsis socialis Levinson is the only other species assigned to this genus. The form present here differs from that species in having the greatest convexity below the anterior to the center, a longer hinge line, and an absence of am ventral ridges and spines, 57 Furthermore 2. socialis has a convex frill. Occurrence. -- Common at 11133.0', occurring in a brown fine to coarsely crystalline limestone. Associated with brachiopods. Occurs rarely at 111111.0' and 11220.0'. meg. -- Holotype, a female left valve, no. 1311. Paratypes three male left valves, nos. 1312, 1313, and 1311;; one male right valve no. 1315. Superfamily Leperditellacea Family Leperditellidae Ulrich 8c Bassler, 1906 Genus Leperditella Ulrich, 1891; me smcies. -- Leperditia fl Coryell and Schenck, 19111, new name fer Leperditia inflata Ulrich, (1892 p. 265) LEPERDI’IEIlA TUMJDA Ulrich Leperditia Midi Ulrich, 1892, p. 261;, pl. 9, figs. 1-3. Leperditella M Ulrich 18911, p. 636; Bassler, 1932, pp. 65, 68; Harris, 1937. hth, 5th pp., fig. 5; 1957, p. 158, p1. 3, figs. lOa-lOb. Occurrence. -- Abundant in Leperditella 2211118. zone at 141014.8' , occurring in a light gray-brown limestone. Associated with Isochilina b, n. sp., few gastropods and crinoid stems. This species also occurs rarely from 11121.0' - 11132.11'. m -- Hypotypes, two right carapaces, nos. 1711 and 1712; one left carapace, no. 1713. Genus Hyperchilarina m, 1957 3222 species. Hyperchiliarina 311132 Harris HIPERCHJIARINA OVATA Harris Hyperchilarina clay; Harris, 1957, p. 115, pl. 5, figs. l7a-l7b. Remarks. -- The specimens present do not have the short beads at 58 the ventral angles of the right valve as described in H. 918.33.. A group of six small spinelets are observed on the ventral angle of the right valve of one specimen. Occurrence. -- Rare at 11133.0'. m. -- Hypotypes, two right valves, nos. 1751 and 1752. Genus Ectoprimitia Boucek, 1936 up: Ecies. -- Primitia comata Krause ECTOPRJMITIA A, n. sp. P1. IV, figSO 5"? Description. -- Valve elongate in lateral outline. Hinge margin long and straight. Anterior cardinal corner nearly round. Posterior cardinal angle nearly acute. Greatest height anterior; greatest width posterior. Anterior margin evenly rounded; posterior margin blunt below the cardinal angle. Sulcus located just anterior to midlength, deepest and pit- 1ike at the base; dorsal and ventral parts of sulcus curves anterior a short distance around a small round node. 81 faintly visible. Posterior and anterior surface of valve reticulate in some specimens. Hingement and internal features unknown. Length of holotype, a left valve, .119 mm, height .22 mm. Remarks/Relationships. - Eoprimitia arcuata Harris is quite similar to this form in anteromedian sulcus and low adjacent lobe. Ectoprimitia a, n. sp. differs in being more elongate and not pos- sessing the slightly umbonate shoulder. Occurrence. -- Common in ostracod zone at 11290.0}. @163. -- Holotype, a left valve, no. 1811. Paratypes, two right valves, nos. 1812 and 1813. 59 Genus Milleratia Swartz, 1936 .1222 species. -- Beyrichia cincinnatiensis Miller MILLERATIA A, :1. 8p. Pl. IV, figs. l'h Description. -- Valve subovate in lateral outline. Hinge line long, straight, and with approximately equal obtuse cardinal angles. Anterior margin evenly rounded; posterior margin less evenly rounded, and extended above; ventral margin very gently convex. Greatest convexity just posterior of the sulcus, where the valve is much in- flated, and projects slightly above the dorsum. Anterior dorsal sulcus deep and straight; sulcus does not reach dorsum; sulcus deepest on the posterior side. A large round slightly raised muscle spot is located ventral to the sulcus. Surface of valve very finely punctate. Hingement and internal features unknown. Length of holotype, a right valve, 1.112 mm., height .88 m. Remarks/Relationships. -- This species agrees closely with the generic description, although it. is of a larger form than the other species assigned to the genus. Swartz (1936), in regard to Milleratia cincinnatiensis (Miller), suggests that because of the shape of the carapace, the umbos, and the character of the median sulcus of this species, that the genus Milleratia Swartz may represent the stock from which the Kloedenellidae were derived. In the species Milleratia _a_, n. sp., these characteristics are are also evident, though the shape of the carapace is more leperditiid in outline. In a few specimens the development of an 81 is observed, which probably is an indication also of an evolutionary stage in the direction of the Kloedenellidae or possibly Kloedeniidae. Occurrence. -- Relatively abundant at h281.0'. Associated with Isochilina g, n. 8p. m. --- Holotype a right valve, no. 1911.~ Paratypes, one left valve, no. 1912; one right valve, no. 1913. Genus Primitia Jones and H011 m species. -- Primitia mundula (Jones) 1885 PRIHITIA A, n. sp. P10 IV, figs. 17, 18 Description. -- Valve small, subquadrate-ovate, compressed convex. Dorsal margin straight with obtuse cardinal angles. An- terior dorsal corner more rounded than the posterior. Anterior margin more evenly rounded than the posterior, which is broader, and ex- tended slightly medially, and is subangulate above and below. Great- est width anterior. Greatest height posterior. In dorsal view, surface of valve descends to the anterior margin in a gentle concave curve; the posterior descends more abruptly along a shorter slope. A narrow distinct sulcus is located medially to slightly an- terior of midlength of the valve; ventral part of sulcus curves slightly anterior. A small prominent node is located anterior to sulcus. Medially on the posterior slope is a low narrow ridge, which becomes confluent with the valve surface posteroventrally and dor- sally. Lateral surface of valve with scattered coarse puncta. Length of holotype, a right valve, .141; mm., height .29 m. Hingement and internal features unknown. Remarks/Relationships. -- This species is similar to Primitia 61 1.123.511. Ulrich in shape of valve. The surface of the valve is also marked by coarse puncta. Primitia a, n. sp. differs in having a random orientation of the puncta, rather than being arranged in curved lines radiating from the sulcus. It also differs in having a less broad sulcus than that species. Occurrence. -- Abundant in ostracod zone at h290.3'. Occurring in a light gray-brown fine to medium crystalline limestone. 32223. -- Holotype, a right valve no. 2811. Paratypes, one right valve, no. 2812; two left valves, nos. 2813 and 2811;. Genus Primitiella Ulrich, 18911 121° mcie . -- Primitiella constricta Ulrich, 1891; PRIMITIELLA A, :1. 8p. Pl. IV, figSQ 19-21 Description. -- Valve moderately large. Dorsal margin straight and long, with obtuse cardinal angles; the anterior more obtuse than the posterior. In lateral view, terminal margins evenly rounded; anterior margin more convex than the posterior; ventral margin slightly convex. Greatest height usually posterior. Postsulcate region of carapace much more inflated than pre- sulcate region; posterior marginal zone depressed; anterior and ven- tral free edge channeled. A shallow sulcus is located dorocentrally. A low presulcate node is located anterior to the ventral region of the sulcus from which, rises a tiny equidimensionfal tubercle. Ventral to sulcus is a slightly raised, round muscle spot. Surface smooth. Hingement and internal features unknown. Length of holotype a right valve, 1.07 m., height .611 mm. 62 Remarks/Relationships. -- This species is similar to 1:. g- pressoreticulata Hes sland in the greater arching of the postsulcate region than the presulcate; position of dorsocentral sulcus; in indistinct presulcate node, and in muscle spot. .Primitiella a, n. sp. differs in having a tiny tubercle rising from the presulcate node, and an anterior and ventral Bhanneled free edge at least in right valves. No reticulation was observed in any specimens, as described in 2. 335- pressoreticulata. Occurrence. -- Abundant at 11230.0' in a finely crystalline gray-brown limestnne. Associated with Cryptophyllus sp. , Primitiella? b, n. sp. mfg. -- Holotype, a right valve, no. 2111. Paratypes, three right valves, nos. 2112, 2113, and 2111;; one left valve, no. 2115. PRDIITIEILA? B, n. sp. Pl. IV, fig. 11 Description. -- Valve subelliptical in lateral outline. Hinge line long and straight, pointed at the extremities. Greatest height anterior. Anterior margin broadly rounded; posterior margin more narrowly rounded; ventral margin gently convex. Lateral surface of valve descends to dorsum along an even slope. Posteroventral part of valve inflated and with a swing to the posterior. A faint, shallow anteriorly directed sulcus is located just posterior to the muscle spot. Located just below the dorsum and anterior to the sulcus is a small, smooth, low swelling. Muscle spot, round, smooth, slightly raised is located anterior to the midlength and at the midheight of the valve; outline delineated by pits. Surface of valve with evenly coarse puncta except for a smooth 63 border along the free edge of the valve. Small area anteroventral to muscle Spot slightly raised and without surface ornamentation. Located posteroventral to the muscle spot are four closely spaced pits, slightly larger than the surrounding puncta. Hingement and internal features unknown. Length of holotype, a left valve, .98 mm., height .61 mm. Remarks/Relationships. -- The weak sulcus, outline, and lack of pronounced nodelike swellings are suggestive of Primitiella, but the highly ornamented surface area leaves the generic status of this form questionable. The shape of the valve appears to correspond quite closely to Opik's illustrated Primitiella indistincta, but does not have the ornamentation of this species. Occurrence. -- Relatively abundant at 1;230.0' .inia finely crystalline gray-brown limestone. mg. -- Holotype, a left valve, no. 2221. Paratypes, two left valves, nos. 2222 and 2223. Order Podocopida Suborder Metacopina Superfamily Healdiacea Harlton, 1933 Family Krausellidae Berdan Genus Krausella Ulrich, 1891; 2222 gecie . -- Krausella inqequalis Ulrich, 1891; ‘ KRAUSELLA ARCUATA Ulrich Krausella arcuata Ulrich, 1891;, p. 691, pl. 1;1;, figs. 117-53; Bassler, 1932, pp. 65-68; Harris, 1937, hth, 5th pp., figs. 1;6a-b; Kay, l91;O, pp. 235, 237, 267; Harris, 1957, p. 252, pl. 10, figs., 5a-Sc. Occurrence. -- Common at 11133.0'. Occurring in a brown fine to coarsely crystalline limestone. 3mg. -- Hypotypes, three left carapaces, nos. 3011, 3012, 6h LIST OF OSTRACOD ZCNES Lefirditella tumida zone Isochilina a zone . Y' Ostracod zone (14119.5') Isochilina 5 zone Ostracod zone (h183.8') Eolegrditia fabulites zme Ostracod zme (h29oo3') Ostracod zone (14312.0') Limestone, light gray-brown; medium to cryptocrystalline. Limestone, very light gray colored, finely crystalline with a back- ground of tiny dolanite crystals, and with dolanite or calcite clusters. Limestone, light gray-brown, coarsely detrital, with a matrix of coarse crystalline calcite crystals. Eoleperditia fabulites, Isochilina b, n. sp., Techilina _c_, n. sp., Platybolbina?- a, n. sp. , Platybolbina F n. sp., Platybolbina _c_, n. sp., ‘Platybolbina h, n. sp. limestone, light gray, sublithograph'c, with small clusters of calcite or dolomite crystals. Milleratia a, n. sp. Limestone, gray, medium crystalline. The fauna stops sharply above, at a sharp change in texture to a sub- lithographic limestme. Isochilina _d_, n. sp., Isochilina f, n. sp., Limestone, light m, medium crystalline to fine grystalline. limestone, light gray, medium crystalline. Primitia _a_, n. sp., Euprimitia la51' osa, Euprimita?a, n. sp., Eugl'mitia b, n. sp., Euprimitla sp., Eurychilina a, n. sp., ctoprimitia a, n. sp. Limestone. Ostracods abundant, but all are recrystallized. 6S PREVIOUSLY DESCRIBED OSTRACODA The following lists previously described Middle Upper Ordovician ostracods, that are present at this location, and gives formatims and localities fran which they have been reported (in part from Harris, 1957). Eoleperditia fabulites (Cmrad) -- file types of this species were orgLnally described fran the Lowville Limestme of St. Joseph's Island, Canada. It has been reported also frau the Black River (Platteville) of Wisconsin; Black River of Minnesota, Kentucky, Tennessee, New York, Alabama; and the Stones River of Tennessee and Appalachian Valley. Reported also from the Mclish, tapmost beds of the Branide, and the Corbin Ranch of Oklahoma. Occurs abundantly in the subsurface Black River of Jackson County, Michigan. Leperditella 2mg (Ulrich) -- Described from the Black River (Lowville) of Ontario, and High Bridge, Kentucky; Black River of Tennessee, Virginia, and Franklin County, Pennsylvania. In the top of the Corbin Ranch Formation, Oklahaua. Abundant in the sub- surface Black River Formation, Jackson County, Michigan. Euprimitia labiosa (Ulrich) -- Reported fran the Presser of Minnesota, and the Hull of Canada. The Ion and Guttenberg of Iowa, and the Bromide in the Arbucle Mountains. Rare in the subsurface Black River Formation, Jackson County, Michigan. Krausella arcuata Ulrich -- Reported fran the Ion of Iowa and Minnesota; Black River of Illinois and Wisconsin; Lowville of High 66 ’av J Bridge Kentucky; Bromide Formation of Oklahuna, and the Llandovery of England. Gama: from the subsurface Black River Formation of Jackson, County, Michigan. Winchellatia longspina Kay -- Described from the Guttenberg Member of the Decorah of Iowa; Bromide Formation of Oklahoma. Occurs rarely in the subsurface Black River of Jackson County, Michigan. Saccelatia kellettae Levinscn -- Reported fran the Brcmide Formatim of Oklahoma. Rare in the subsurface Black River Formation, Jackson County, Michigan. Hypgrchilarina ovate Harris -- Described from the Tulip Creek Form- ation of Oklahoma. Rare in the Black River Formation of Jackson County, Michigan. Plat olbina schadidea Kesling -- Reported fran the Bony Falls limestone, Delta County, Michigan. Occurs rarely in the subsurface Black River Formation, Jacksm County, Michigan. 67 sun-am The estracod fauna of this core has been found to be abundant. The majority of the species being distributed among seven zones. Of the thirty-one species observed, twenty-three are_described as new. The ostracod fauna is interesting because of the presence of many specimens of leperditiids with spines, which have been previously thought to be unusual in the.family Leperditiidae. Hinge dentition which has not been hitherto described in known Ordovician leperditiids is observed in a few specimens. .L.second occurrence of Platybolbina Henningsmoen is here re- ported. This genus had previously been.known only from Northern Europe. Kesling (1960) reports the first occurrence of this genus in North America, from the Bony Falls Limestone, Delta County, Michigan. The ostracod fauna studied here contains typical Ordovician genera. Six of the species observed here are reported also from the Bromide, Tulip Creek, and MbLish Formations of Black River age in Oklahoma. Saccelatia kelletae Levinson, fiyperchilarina'gzatgIHarris, and the genus Diplopsis Levinson, which have been previously reported only from the Bromide and Tulip Creek Formations, are a1So reported here. Several species of Platybolbina Henningsmoen are present. The majority of them.being new. 2. schadidea.Kesling, is the only species of this genus identical with the Bony Falls holotype. Eoleperditia fabulites (Conrad) occurrs abundantly here, and has also been reported 68 fran the Bony Falls Limestone. Because of the restricting locality of this collection, and the lack of abundant information on the character of the faunas of similar age, it is difficult to draw any definite conclusims re- garding the resemblance to other described Black River ostracod faunas, or in delineating any geographic boundaries. With further work, the fauna of other localities may prove to be more similar to these forms than those of the Simpson Group of Oklahoma. On the other hand the Simpson ostracod fauna may be unlike the fauna of this locatim, because the new species described here do not occur there, and many Simpson forms do not occur at this locality. Possibly these species have just not been found, or some forms for acne reason are more restricted geographically than others . 69 REFERENCES Baker, W.H. , 1951. A simple technique for extracting microfossils: The Micropaleontologist, vol. 5, no. 1;, p. 39. Bassler, R.s., 1919. The Cambrian and Ordovician deposits of Mary- land: Maryland Geol. 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Unpublished Master of Science thesis, Michigan State University. Hanna, G.D., 1928. Freezing and thawing to disintegrate shales. Journ. Paleontol., vol.2, p. 131. Harris, RN. , 1931. The stratigraphy and pmsical characteristics of the Simpson’group. Oklahoma Geol. Survey, Bull. 55, PP. 87-95, pls. 3, s, 10, 11, 1h. ’ ___, 1937. Field conference for the study of the Simpson formation. Oklahoma City Geol. Soc. , Guidebook, March 5-6, 1th, 5th pages. _, 1957. Ostracods of the Simpson group. Oklahoma Geol. Survey, Billie 75, 333 Ppo, 10 pls. 72 Henningsmoen, G. , 19118. The Tretaspis series of the Kullatorp core. Univ. Upsala, Geol. Instit., Bull. , vol. 32, (Ostracods, PP. hOB-hl9, pl. 25). Hessland, I., 191:9. Investigations of the Lower Ordovician of the Siljan district, Sweden. I. Lower Ordovician ostracods of the Siljan district, Sweden. Bull. Geol. Instit. Upsala, vol. 33, pp. 97-h08, 26 pls., 3 figs. Horowitz, M., 1961. The St. Peter-Glenwood problem in Michigan. Unpublished Master of Science thesis, Mich. State Univ. Howe, H.V., 1955. Handbook of ostracod taxononw, Louisiana State Univ. , Studies, Physical Sci. ser no. 1 p1-389. , 1962. Ostracod taxonomy. Lousiana State Univ. Press. 366 pp. Hussey, R.C., 1950. The Ordovician rocks of the EscanabaoStonington Area. Mich. Geol. Soc. , Annual Field Trip Guidebook, June 2-3, 1950, 2h pp., pls. 1-3, map. , 1952. The Middle and Upper Ordovician rocks of Michigan. Mich. Dept. Cmserv., Geol. Survey Div., Publ. 1:6, Geol. Ser. 39. 39 pp., pls. 1-10. Jaanusson, Valdar., 1957. Middle Ordovician ostracods of Central and Southern Sweden. Bull. Geol. Instit. Univ. Upsala, vol. 37, pp. 173-hh2, 15 pls., 1:6 figs. (Reprinted as Publ. Pal- aeontol. Instit. Univ. Uppsala, no. 17). Jones, T.R., 1856. Notes on the Paleozoic bivalved Entomostroca, no. 3. Some species of Leperditia. Ann. Mag. Nat. Hist. , ser. 2, vol. 17, pp. 81-101, p15. 6-7. 73 Jones, T.R., 1858a. On Palaeozoic Entomostraca of Canada. Geol. Surv. Canada, Canadian Organic Remains, Dec. 3, vol. 1, pp. 91-101, pl. 11. ____, 1858b. Notes on the Paleozoic bivalved Entomostraca no. 1:. North American Species. Ann. Mag. Nat. Hist. , ser. 3, vol. 1, pp. 21:1-55. pls. 9-10. _____, 1891. Contributions to Canadian Micropaleontology, Pt. 3. On some Ostracods from the Cambro-Silurian, Silurian, and Devonian rocks. Geol. Nat. Hist. Survey Canada, pp. 59-99, pls. 10-13. Kay, 0.14., 1931:. ,Mohawkian Ostracods: Species common to Trenton faunules from the Hull and Decorah formation. Journ. Paleontol. Vol. 8, pp. 328-310, pls. hit-1:6. _, 191:0. Ordovician Mohawkian Ostracods: Lower Trenton Decorah fauna. Journ. Paleontol., vol. 11:, pp. 23h-269. Keenan, J.F., 1951. Ostracodes from the Maquoketa shale of Missouri. Journ. Paleontol., vol. 25, pp. 561-571:, Pls. 78-79. Kesling, R.V., 1951. Terminology of ostracod carapaces. Univ. Mich., Contrib. Mus. Paleontol., vol. 9, pp. 93-171, 18 pls., 7 text £138., 5 charts. _______, 1955. Notes on two Ordovician ostracods from Estonia. Contrib. Mus. Paleontol. Univ. Mich., vol. 12, no. 13, pp. 259- 272, 1 p1. ______, 1958. A new and unusual species of the ostracod genus Hearnannina from the Middle Silurian Hendridks Dolomite of Michigan. Contrib. Mus. Paleontol. Univ. Mich., vol. 11:, no. 9’ PP. 1113-1148, 1 Pl. 7h Kesling, R.V., Crafts, F.S., Darby, 11.0., Shubak, K.E., and Smith, 11.11., 1960a. Middle Ordovician Black River ostracods from Michigan, Introduction and Part I, The Nature of.Macronote11a. Contrib. Mus. Paleontol. University of Mich., vol. 15, no. 13, pp. 293- 311» 3 p1. , 1960b. Ibid, Part II, Levisulculus and Eurychilina. Contrib. Mus. Paleontol. Univ. Mich., vol. 15, no. 15, pp. 3h9-363, h pls. , 1960c. Ibid, Part III, Platybolbina. Contrib. Mus. Pal- eontol. Univ. MiCh., vol. 15, no. 16, pp. 365-385, (B pls). Kesling, R.V., Hall, D.D., Melik, J.G., 1962. Ibid, Part IV. Species of Colacchilina (new'genus)'Laccochilina, and.Hesperide11a. Contrib. Mus. Paleontol. Univ. Mich., vol. 17, no. 8, pp. 205- 213, 2 p13. Kirchner, Z.M., 1958. A new method of hard-rock maceration, micro- paleontology, vol. h, no. 3, pp. 327-8. Kirschke, N.M., 1962. A petrographic core analysis of the Lower and Middle Ordovician rocks, Pulaski Field, Jackson County, Mich. Unpublished Master of Science thesis, Mich. State Univ. Kummerow, E., 1931. Orientation of the carapace of Paleozoic Ostracods. Journ. of Paleontol., vol. 5. pp. 155-9. Layne, N.M., 1950. A procedure for shale disintegration; The Micro- paleontologist, vol.1:, no. 1, p. 21. Levinson, S.A., 1951. Thin sections of Paleozoic Ostracods and their hearing on taxonomy and morphology. Journ. Paleontol., vol. 25, pp. 553-560, pl. 77. , 1961. New genera and species of Bromide (Middle Ordovician) ostracodes of Oklahoma. pp. 359-36h, 1 p1. 75 MacVicar, D.G., 1951. Extraction of fossils by heat: The Micro- paleontologist, vol. 5, no. 3, p. 15. Moore, R.C., 1961. Treatise on Invertebrate Paleontolog, Part Q Arthropoda 3. G.S.A. and Univ. of Kansas. Press, 1:112 pp. Poulsen, 0., 1937. On the Lower Ordovician faunas of eastern Green- land. Meddlelelser om Gronland, vol. 119, no. 3, pp. 56-61, figs. 16-17. Redmond, C.D., 1953. Further notes on the disintegration of shale samples; The Micropaleontologist. vol. 7, no. 2, p. 1:7. Ruedemann, R., 1901. Trenton conglomerate of Rysedorph Hill, New ‘ York, and its fauna. New York State Mus. , Bull. 1:9, Paleon- tology Paper no. 2, (Ostracods. pp. 70-87, pls. 5-7). Scott, 11.11., 1951. Instars and shell morphology of Eoleperditia malt“. Hourn. Paleontol., vol. 25, no.3, pp. 321-26, pl. 51, 3 figs. Sohn, J.G., 1956. The transformation of opaque calcium carbonate to translucent calcium fluoride in fossil ostracoda., Journ. Paleontol., vol. 30, no. 1, pp. 113-:L1J:. Spivey, R.C., 1939. Ostracodes from the Maquoketa shale, Upper Ordovician, of Iowar Journ. Paleontol., vol. 13, pp. 163-175, pl. 21. Swain, F.M., 1957. Early Middle ostracods of eastern United States. Journ. Paleontol., vol. 31, pp. 528-570. _____, Cornell, J.R., and Hansen, D.L., 1961. Ostracods of the families Aparchitidae, Aechminidae , Laperditellidae, Drepan-. ellidae, Eurychilinidae and Punctaparchitidae from the De- corah shale of Minnesota. Journ. Paleontol., vol. 35, no. 2, PP. 316-372, pls. 1:6-50. 76 Swartz, 1314., 1936. Revision of the Primitiidae and Beyrichiidae, with new Ostracods from the Lower Devonian of Pennsylvania. Journ. Paleontol., vol. 10, pp. 51:1-586, pls. 78-89. ____, 191:9. Muscle marks, hinge and overlap features, and class- ification of some Leperditiidae. Journ. Paleontol. , vol. 23, PP- 306-327, pls. 65-67. Switzer, G., and Bohoot, A.J., 1955. The mineral composition of some microfossils. Journ. Paleontol., vol. 29, no. 3, pp. 525-533. Teichert, C.T., 1937a. A new Ordovician fauna from Washington Land, North Gronland, vol. 119, no. 1 (Ostracod pp. 113-65, pl. 1:, figs. 9-12, pls. 5, 6). ____, 1937b. Ordovician and Silurian faunas from Arctic Canada, (Reprinted from Rept. of 5th Thule Exped. 1921-1921:, vol. 1, no. 5). Copenhagen Univ. Min., Geognost. Mus. Communicat. Paleontologie, no. 59, 169 pp.) 21: pls. Ulrich, E.O., 1890, 1891. New and little known American Paleozoic Ostracoda. Journ. Cincinnati Soc. Nat. Hist. , vol. 13, pp. 101:-37, pp. 173-211, 8 p18. , 1892. New lower Silurian Ostracoda, no. 1, Amer. Geologist, vol. 10, no. 5, pp. 263-270, pl. 9. , 1891:. The Lower Silurian Ostracods of Minnesota. Final Rept. Geol. and Nat. Hist. Surv. Minnesota, vol. 3, pp. 629-93, pls. 113-116, £1g8. 1:6-5l. _, & Bassler, 11.3., 1923. Morphology and classification of Paleozoic Ostracods. Maryland Geol. Survey, Silurian. vol. , pp. 2n-381’ figs. 1.1-260 77 Walcott, C.D., 1882. Description of new Trenton fossils of New York. New York State Museum Nat. Hist., 35th Ann. Rept., pp. 213-211:, pl. 17, figs. 10-11. Weller, S., 1903. Report on paleontolog, pt. .3. The Paleozoic faunas. New Jersey Geol. Survey, pp. 7-388, pls. 1-53. EXPLANATION OF PLATE I (All figures x6.5) Isochilina a, n. sp. Fig. 1. Fig. 2. FigSo 3, h, 6. Fig. 5. Isochilina b, n. sp. Fig. 70 Figs. 8-10. Fig. 13. Fig. 15. Isochilina _d_, n. sp. FigS. 16, 170 Isochilina f, n. sp. Page 0 O O O O O O O O O O O O O O O O O O O O 19 Right lateral view of holotype. Anterior view of holotype. Left lateral view of three valves, para- types; valves with matrix on midventral area. Right lateral view of valve, paratype; valve with broken Spine and matrix on midventral area. OOOOOOOOOOOOOOOOOOOOOO 25 Left lateral view of imature valve, paratype. Right lateral, dorsal, and anterior views of valve, paratypes. In figure 8, valve with matrix midventrally. Left lateral view of holotype. Anterior cardinal corner not complete. Matrix on valve midventrally. Right lateral view of valve, paratype. Midventral spine broken. OOOOOOOOOOOOOOOOO O... 31 Right lateral and anterior view of holotype. OOOOOOOOOOOOOOOOOOOOO 3h Figs. 11:, 18, 19 Right lateral, ventral, and anterior view of holotype. 78 79 EXPLANATION OF PLA‘IE II Isochilina g, n. sp. Figs. 1, he Figs. 3’ So Fig. 2. Isochilina g, n. sp. Fig. 6. Isochilina g, n. sp. Fig. 7. Fig. 8. Diplgpsis? 3, n. sp. Fig. 9. Fig. 11. Figs. 10, 15. Figs. 13’ 16o Page 0 O O O O O O O O O O O O O O O O O O O 35 Right lateral views of holotype. Fig. 1 (x 6.5). Fig. 1: (x 9). Right lateral views of two valves, paratypes (x 6.5). Left lateral view of valve, paratype (x 6.5). OOOOOOOOOOOOOOOOOOO 28 Left lateral view of holotype (x 6.5). ................... 32 Right lateral view of holotype ; posterior cardinal corner broken (x 8). Ventral view of right valve, holotype (x 8). .'.................. 55 Dorsal view of left male valve, paratype (x 10.5) Left lateral view of male valve, paratype (x 10.5) Left lateral views of two male valves, paratypes (x 10.5). 13. Dorsal view of female left valve, holotype (x 10.5). 16. Left lateral view of hOIOtypeo E o;_e_Perditia ram-1&8 (c onrad) O O O O O O O O O O O O O O O Q 18 Figs. 1h, 18. Fig. 170 Left lateral view of two valves, paratypes (x 605)- Right lateral view of valve, hypotype. 80 EXPLANATION OF PLATE III (All figures x 21.5) Plajybolbina g, n. sp. Fig. la Fig. 2. Platmolbina :13, n. sp. Fig. 3. Fig. 5. Figs. 6, ll. Platybolbina sp. . . Fig. 1:. Platybolbina g, n. sp. Fig. 8. Figs. 7, 9, 10. Platlbalbina 2, no Sp. Fig. 12. Figs. 213-150 Page .................. 1:6 Left lateral view of holotype. Left lateral view of valve, paratype. Posterior corner broken; midventrally valve with matrix. .................. 1:1: Left lateral view of holotype, female. Matrix on anterior margin. Right lateral view of female, paratype. hefLeft lateral view of female, paratype. 11. Left lateral view of male, paratype, matrix anterior. O O O O O O O O O O O O O O O O O O 51 Right lateral view of valve. 0 O O O O O O O O O O O O O O O O 0 1‘3 Left lateral view of male valve, holotype. Left lateral and two right lateral views of valves, paratypes. 1:1 Left lateral view of male valve, holotype. Left lateral views of three female valves, paratypes. Fig. 11: with matrix anterior and posterior. 82 Platybolbina _x, n. sp. Fig. 16. Fig. 17. Plamolbina h, n. sp. Fj-g. 18. Fig. 19. EXPLANATION OF PLA'IE III (continued) Page Left lateral view of holotype, sausage-like structure on frill. Anterior and ventral areas with matrix. Left lateral view of valve, paratype. Sausage-like structure on frill. Frill broken. Anterior and ventral areas with matrix. ........ 50 Left lateral view of male valve, holotype. Frill broken ventrally. Matrix on anterior corner, and ventrally on frill. Left lateral view of male valve, paratype. 81: EXPLANATION OF PLATE IV (All figs. x 21.5 except 22-25) Page Milleratiag,n.sp.................... 59 Figs. 1, 2. Dorsal and right lateral fiew of holotype. Figs. 3, 1:. Left and right lateral views of valve, paratype. EctoLrimitiag,n.sp................... 58 Figs. 5, 7. Right lateral view of valves, paratypes. Fig. 6. Left lateral view of holotype. Primitiella?b,n.sp................... 62 Fig. 8‘. Left lateral view of holotype. Euprimitiasp....................... 1:2 Fig. 9. Right lateral view of male valve. Fig. 10. Left lateral view of female valve. Euprimitiab,n.8p.................... 1:1 Figs. 11, 13. Right lateral view of valves, paratypes. Fig. 12. Right lateral view of holotype. Euprimitia73,n.spo .................. 140 Figs. 11:, 15. Left lateral view of valves, paratypes. Fig. 16. Left lateral view of holotype. Primitiag,n.sp...................... 60 Fig. 17: Left lateral view, paratype. Fig. 18. Left lateral view of holotype. Primitiellag,n.sp. .................. 61 Fig. 19. Right lateral view of holotype. Figs. 20, 21. Right lateral view of valves, paratypes. 85 PLATE IV EXPLANATION OF PLATE IV (continued) Page erikella-Egn.sp.oo.................. 51!. Fig. 22. Right lateral view of holotype (x 10.5). Fig. 23. Right lateral view of valve, paratype (x 10.5). Figs. 21:, 25. Left lateral views of same valve, paratype (x 10.5) and (x 15). Eurychilinag,n.sp. .................. 38 Fig. 26. Left lateral view of holotype. Platybolbinag,n.sp.................... 1:9 Fig. 28. Lateral view of right valve, paratype; anterior and posterior margins broken, matrix at anterior and posterior margins. Fig. 29. Lateral view of left valve, paratype. Posterior corner and anterior and posterior terminus of frill broken. Valve with matrix at broken areas. Platybolbinag,n.sp................... 1:1 Fig. 30. Left lateral view of male valve, paratype. Euqchilinaa,n.sp. .................. 38 Fig. 27. Right lateral view of pal-at”... 87 ‘3 MI, . .\. an a. v s ...... a: ...-.a £6.11...» ...... ... A ‘rtt- 1111 1 WI" 31293 03175 3 (N 1111