Ostracoda From Wells 

in North Carolina:

Part 2. Mesozoic Ostracoda

GEOLOGICAL SURVEY PROFESSIONAL PAPER 234-B
Ostracoda From Wells 

in North Carolina:

Part 2. Mesozoic Ostracoda

By FREDERICK M. SWAIN

GEOLOGICAL SURVEY PROFESSIONAL PAPER 234-B

Descriptions, illustrations, 

geographic distributions, and 

stratigraphic ranges of 

microfossils

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1952
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L, Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office 

Washington 25, D. C. - Price 40 cents (paper cover)
CONTENTS

Abstract.--___-___-__„___-_-_______________________

Introduction.. _ _____________________________________

Stratigraphic Summary__________________________

Mesozoic and older rocks in Esso Standard Oil Co. 

Hatteras Light well No. 1___________________

Mesozoic rocks in Esso Standard Oil Co. North 

Carolina Esso well No. 2______________________

Stratigraphic distribution of the Ostracoda________

Systematic descriptions._____________________________

Cytherellidae__ _ ______________________________

Cytherella. ------_________-________________

Cy therelloidea_ ___________________________

Cypridae ______________________________________

Cypris___ ________________________________

Paracypris_ _ _______________________________

Ilyocypris ___ _____________________________

Bairdiidae- ____________________________________

Bairdia__________________________________

Bairdoppilata____________________________

Bairdiocypris__ _ __________________________

Page 

59 

59 

59

62

67

68

68

68

68

68

70

70

70

70

71

71

71

72

Systematic descriptions—Continued 

Cytheridae_ _________________

Apatocythere_____ _ ________

Schuleridea- ______________

Asciocythere ______________

Haplocytheridea_ __________

Brachycythere___________

Cythereis_ ________________

Protocy there __ ____________

Pterygocythereis____ _ ______

Cy theropteron _____________

Krithe________________

Gomphocythere____ __ _ _ _.

Monoceratina_ ____________

Hutsonia. ________________

Macrodentina_ ____________

References. _ ______________________

Index.___________________________

Page

72

72

74

75

78

80

81

85

85

86

87

87

88

88

89

89

91

ILLUSTRATIONS

Page 

PLATE 8. Cytherellidae, Cypridae, Bairdiidae, and Cytheridae_________._____-____-_-_-___-_-_--__-__--_---- Following index

9. Cytheridae________________________________________________________________ _ _______________ Following index

FIGURE 4. Index map showing locations of wells._______________________________-__-_--___----___----------_--_---- 60

5. Stratigraphic setions of the Upper Cretaceous rocks in Hatteras Light well No. 1 and North Carolina Esso well

No. 2________-______-_-____.________.____________.______•___._____-__--_--_--____-----_-_--------_- 61

6. Stratigraphic sections of the Lower Cretaceous in Hatteras Light well No. 1 and North Carolina Esso well No. 2__ 61

7. Stratigraphic section of Upper Jurassic(?) and pre-Cambrian rocks in Hatteras Light well No. 1_ ——— __________ 62

in

Ostracoda From Wells in North Carolina

Part 2, Mesozoic Ostracoda

By F. M. SWAIN

ABSTRACT

This paper describes and illustrates 47 species of Mesozoic 

Ostracoda from two deep wells in eastern North Carolina. 

Twenty-two of the species are new. The following genera, one 

of which is new, are represented in the collection: Cytherella 

Jones, Cytherelloidea Alexander, Cypris Miiller, Paracypris 

Sars, Ilyocyprist Brady and Norman, Bairdiaf McCoy, Bairdoppilata Coryell, Sample and Jennings, Bairdiocypris? Kegel 

Apatocytheref Triebel, Schuleridea Swartz and Swain, Asoiocythere Swain, n. gen., Haplocytheridea Stephenson, Brachycythere Alexander, Cythereis Jones, ProtocytJiere Triebel, Pteryffocythereis Blake, CytJieropteron (Eocytheropteron) Alexander, 

Krithe Brady, Crosskey and Robertson, GompJiocytJiere Sars, 

Monoceratina Roth, Hutsonia Swain, and Macrodentina Martin.

Equivalents or partial equivalents of the following stratigraphic units arranged in descending order are represented in 

the subsurface of eastern North Carolina:

Upper Cretaceous

Peedee (?) formation

Black Creek (?) formation

Beds of Eutaw(?) age

Beds of Eagle Ford( ?) age

Tuscaloosa (?) formation 

Upper and Lower Cretaceous

Beds of Washita(?) age 

Lower Cretaceous

Beds of Fredericksburg(?) age

Beds of Trinity (?) and pre-Trinity(?) age undifferentiated 

Upper Jurassic (?)

Beds of Schuler(?) age 

Pre-Cambrian

Descriptions of the lithologic sequence in each of the two 

wells are given. The stratigraphic subdivisions differ in several 

respects from those suggested in a previous paper (Swain, 1947).

INTRODUCTION

The Ostracoda described herein were obtained from 

two deep wells in eastern North Carolina: (1) Esso 

Standard Oil Co., Hatteras Light well No. 1, long. 

T5°31'4" W., lat. 35°15'0.5" N., Cape Hatteras, Dare 

County, N. C.; (2) Esso Standard Oil Co., North Carolina Esso well No. 2, long. 75°33'54" W., lat. 35°42'12" 

N., Pamlico Sound, Dare County, N. C. The locations 

of the wells are shown in figure 4.

A brief description of the stratigraphic units encountered in the two wells has been published (Swain,

1947). A survey of the regional subsurface stratigraphy and structure in eastern North Carolina, together with informative discussion of the Hatteras 

Light well and North Carolina Esso well No. 2, has 

been provided by Spangler (1950). The Cenozoic 

Ostracoda from the Esso Standard Oil Co. wells and 

from several water wells in the eastern part of the 

State have been described in a previous paper (Swain, 

1951). Study of the extensive foraminiferal fauna obtained from the wells is still underway.

Sincere appreciation is expressed to officials of the 

Esso Standard Oil Co. for providing the samples of 

their two deep wells; and to John B. Reeside, Jr., James 

A. Peterson, William D. Quinlivan, Lawrence E. 

Monley, and Louis M. Perry of the Geological Survey 

for their valuable assistance in this study. The study 

was supported mainly by the Paleontology and Stratigraphy Branch of the United States Geological Survej7 

but funds from the Graduate School of the University 

of Minnesota also provided aid in laboratory and bibliographic work.

STRATIGRAPHIC SUMMARY

The lithologic units in the two Esso Standard Oil 

Company wells are briefly described below, and the 

correlations between the wells are presented in figures 

5 and 6.

The strata from 8,500 to 9,878 feet depth in the 

Hatteras Light well No. 1 may represent the Upper 

Jurassic, and perhaps are equivalent to the Schuler 

formation of the central Gulf region because (1) the 

unit contains three species of Ostracoda that occur 

in the Schuler, (2) an ostracode species found in the 

Wealden (Neocomian) of Germany occurs just above 

8,500 feet, (3) the upper layers of the unit are cavernous dolomitic limestone that appears to have undergone 

solution and weathering, suggesting an unconformable 

contact with overlying strata, (4) there is general 

lithologic similarity of the unit to the Schuler formation of southernmost Arkansas (Swain, 1944, pp. 594- 

600). Figure 7 shows the Upper Jurassic (?) and

59
60 OSTRACODA FROM WELLS IN NORTH CAROLINA

78°

NORTHAMPTON

,' H E R T F 0 R D

SAMPSONlQU

1 Esso Standard Oil Co. Hotteros Light I

2 Esso Standard Oil Co North Carolina Esso 2

10 0 50 Miles 

!,,,,! I I I I I

FIGURE 4.—Index map showing locations of wells.

pre-Cambrian rocks penetrated in Hatteras Light well 

No.l.

The Tuscaloosa( ?) formation in the Hatteras Light 

well No. 1 rests upon a thin marine bed believed to be 

of Washita age because of the occurrence of the Lower 

Cretaceous ostracode Cytheropteron (Eocytheropteron). The underlying 435 feet of marine strata contain Gytheropteron (Eocytheropteron) tumidwm, Alexander and are believed to be Fredericksburg in age.

The strata of Washita(?) and Fredericksburg(?) 

age apparently are absent from the North Carolina 

Esso well No. 2 and the Tuscaloosa(?) formation rests 

unconformably upon strata that contain ostracodes of 

Trinity type.
MESOZOIC OSTRACODA 61

Esso Standard Oil Co. 

North Carolina, 

ESSQ Well No. 2

Esso Standard Oil Co.,

Hatteras Light

Well No. 1

EXPLANATION

Sandstone Conglomerate Limestone Sandy and Gray shale Green and Sandy shale 

shaly limestone red shale

FIGURE 5.—Stratigraphic sections of the Upper Cretaceous rocks in 

Hatteras Light well No. 1 and North Carolina Esso well No. 2.

Esso Standard Oil Co., 

North Carolina, 

Esso Well No. 2

Esso Standard Oil Co.,

Hatteras Light

Well No. 1

Tuscaloosa (?) formation 

X4923' Beds of Washita (?) age, 5530

FIGURE 6.—Stratigraphlc sections of the Lower Cretaceous 

Hatteras Light well No. 1 and North Carolina Beso well

rocks in 

No. 2.
62 OSTRACODA FROM WELLS IN NORTH CAROLINA

Esso Standard Oil Co.,

Hatteras Light

Well No. 1

Beds of Early 

Cretaceous (?) age

EXPLANATION

Conglomeratic limestone

Green and red shale

Anhydrite

^granitic igneous rock

VERTICAL SCALE IN FEET

Total depth 10,054 feet ~J

FIGURE 7.—Stratigraphic section of the Upper Jurassic (?) and preCambrian rocks in Hatteras Light well No. 1.

MESOZOIC AND OLDER ROCKS IN ESSO STANDARD OIL 

COMPANY HATTERAS LIGHT WELL NO. 1

Depth Thickness 

(feet) (feet) 

Upper Cretaceous 1

Peedee(?) formation

Sandstone, white, fine-grained, slightly 

porous, in part with siliceous cement, 

more coarsely glauconitic than overlying Paleocene?; some beds of sandy, 

partly calcareous siliceous shale and 

chert. Core 3,063-3,070 feet, recovered 

30 inches of white, slightly calcareous, 

finely glauconitic, highly siliceous shale, 

sp gr 2.82 2______________ 3, 033-3, 080 47 

Chalk, light-gray and white, sandy, siliceous, glauconitic; with interbedded 

siliceous marl_______________ 3,104 24 

Marl, light-gray and white, highly siliceous, finely glauconitic; Cytherella cf. 

O. obesa Alexander, Cytherella spp 8_ 3,147 43

1 The Cenozoic rocks in this well have been described (Swain, 1947; 

Spangler, 1950). Spangler (1950, fig. 9) places the Cretaceous and 

Tertiary contact at 2,415 feet below sea level at a depth of 2,439 feet, 

but there are ostracodes indicative of an Eocene age in core samples 

from depths of 2,531-2,541 feet and 2,593-2,603 feet and in drill-cutting 

samples as deep as 2,840-2,850 feet (Swain, 1951, pp. 10-11 and 12).

2 Specific gravity determinations were supplied by Esso Standard 

Oil Co.

3 Not described because too poorly preserved.

Upper Cretaceous—Continued Depth Thickness 

Black Creek (?) formation (feet) (feet) 

Shale and marl, medium- and light-gray; 

with units containing white chalk layers 

from 3,147-3,197 feet, 3,205-3,235 feet, 

3,270-3,290 feet and between 3,480-3,660 

feet; sandy unit 3,520-3,540 feet; abundant glauconite and nodular siderite 

3,205-3,235 feet. Core 3,160-3,170 feet, 

recovered 10 feet, white, chalky, finely 

sandy, slightly glauconitic, slightly fossiliferous limestone and marl, sp gr 

ranges from 1.89 to 2.02. Core 3,269- 

3,279 feet, recovered 10 feet, mediumgray, laminated calcareous shale containing abundant Foraminifera and 

oyster fragments. Core 3,380-3,390 feet, 

recovered 30 inches, medium-gray calcareous shale containing abundant small 

Foraminifera, Inoceram/us prisms, and 

Haplocytherideaf berryi Swain, n. sp.; 

sp gr 2.32. Core 3,500-3,510 feet, recovered 8 inches, medium- and darkgray, silty, calcareous, slightly micaceous shale containing Foraminifera 

and Brachycythere sphenoides (Reuss) ; 

sp gr 2.19. Core 3,657-3,666 feet, recovered 16 inches, grass-green and graybrown, mottled, sandy, glauconitic shale, 

and shaly sandstone containing large 

angular and subrounded quartz grains; 

sp gr 2.13; part of this core belongs 

to subjacent unit. Other Ostracoda obtained from drill cutting samples in the 

Black Creek (?) formation are: Cytherella navarroensis Alexander (3,130- 

3,140 feet), Bairdoppilata pondera, Jennings (3,410-3,420 feet), Haplocytherideat sp. aff. H? plummeri (Alexander) 

(3,550-3,560 feet), Brachycythere darensis Swain, n sp (3,200-3,210 feet), 

Brachycythere nausiformis Swain, n. sp. 

(3,640-3,650 feet), Protocythere paratriplicata Swain, n sp (3,240-3,250 feet), 

Cythereis Mcomis Israelsky (3,625 feet). 

Spangler (1950, p. 113) reported the following Foraminifera from the Black 

Creek formation: Globotruncana area 

(Cushman), Planulina, taylorensis 

(Carsey), Kyphopyxa christneri (Carsey), Vaffinulina regina, (Plummer) 

(=V. texana Cushman)_________ 3,660 513 

Beds of Eutaw (?) age 4

Sandstone, white and light-gray, fineto coarse-grained and conglomeratic, 

partly calcareous, argillaceous and 

glauconitic; upper 10 to 20 feet contain 

limonitic material staining quartz grains 

and interstitial clays, suggesting 

weathering, but sandy portion of core 

3,657-3,666 feet as described in overlying unit contains no observable li4 Swain (1947) referred this unit to the Magothy? formation. 

Spangler (1950, p. 130) terms approximately the same Stratigraphic 

unit the Eutaw formation. As here used, "beds of Eutaw (?) age" 

implies approximate but not definitely proved Stratigraphic equivalence 

to the Eutaw formation of the central Gulf region, the Austin chalk of 

Texas, and the Magothy formation of the Middle Atlantic States.
MESOZOIC OSTRACODA 63

Upper Cretaceous—Continued Depth Thickness 

Beds of Eutaw (?) age—Continued (feet) (feet) 

monitic coloring. Core 3,693-3,703 feet, 

recovered 3 feet, light-gray, fine-grained, 

partly argillaceous, micaceous, slightly 

glauconite sandstone, with flakes of a 

mineral resembling chlorite; some flakes 

of muscovite are partly altered to a 

mineral resembling chlorite; sp gr 2.60; 

Asciocythere macropunctata Swain, 

n. sp., Cythereis quadrialira Swain, n. sp. 

(drill-cutting sample 3,750-3,760 feet) __ 3, 755 95

Sandstone, light-gray and white, fine- to 

coarse-grained, calcareous, glauconitic. 

Core, 3,827-3,837 feet, recovered 6 feet 

light gray-brown, fine-grained, partly 

calcareous, micaceous, glauconitic sandstone, containing flakes of a mineral resembling chlorite; sp gr ranges from 1.96 

to 2.41. Ostracoda obtained from drillcutting samples are: Asoiocy'there? acuminata Swain, n. sp. (3,780-3,790 feet), 

Brachycythere nausiformis Swain, n. sp. 

(3,780-3,790 feet), Monoceratina sp. aff. 

M. semiornata Alexander (3,800-3,810 

feet) ______________________ 3,855 100

Sandstone, fine- and coarse-grained, poorly 

consolidated; conglomeratic and ferruginous in upper 50 feet; well sorted, 

averaging 2 mm, and containing milky, 

rose, and amethystine quartz grains 

from 3,900-3,930 feet; ferruginous in 

lower 50 feet. Core 3,930-3,940 feet, recovered 10 feet, white, fine- and coarsegrained, subrounded and angulargrained friable sandstone, sp gr 

1.88. Core 4,042-4,052 feet, recovered 

4 feet 6 inches, light-gray, fine-grained, 

argillaceous, micaceous sandstone, containing flakes of chlorite?; sp gr ranges 

from 1.97 to 2.04. Haplocytheridea? sp. 

aff. H? plummeri Alexander obtained 

from drill cuttings (3,990-4,000 feet)_ 4,110 255

Sandstone, light-gray and white, fine- and 

medium-grained, calcareous, partly glauconitic and micaceous. Core 4,152-4,162 

feet, recovered 10 feet, light-gray, finegrained, angular-grained, calcareous, 

very micaceous, glauconitic sandstone; 

sp gr 1.83. Core 4,275-4,285 feet recovered 4 feet, light-gray, fine- and very 

fine-grained, argillaceous, micaceous 

sandstone, containing flakes of a mineral 

resembling chlorite; sp gr 2.01. Cythereis ornatissima (Reuss) (4,260-4,270 

feet)____________________ 4,288 178 

Beds of Eagle Ford (?) age

Shale, light-gray, partly sandy and calcareous, glauconitic, and containing thin 

layers of white, fine-grained, calcareous, 

chloritic? sandstone in upper half. Core 

4,385-4,395 feet, recovered 28 inches, 

light-gray, very sandy, micaceous shale, 

containing flakes of a mineral resembling 

chlorite; sp gr 2.42. Core 4,485-4,495 

feet, recovered 8 feet 6 inches, light gray, 

silty, micaceous shale; sp gr ranges from 

961964—52——2

Upper Cretaceous—Continued Depth Thickness 

Beds of Eagle Ford (?) age—Continued (feet) (feet) 

2.31 to 2.34; Haplocytherideaf graysonensis (Alexander). Ostracoda obtained 

from drill-cutting samples of beds of 

Eagle Ford (?) age are Bairdia cf. B. 

alexandrina Blake (4,470-4,480 feet), 

Cythereis cf. C. bicomis Israelsky 

(4,320-4,330 feet), Cythereis ornatissima 

(Reuss) (4,410-4,420 feet), Pterygocythereis cf. P. toJciana (Israelsky) (4,440- 

4.450 feet)__________________ 4,542 254 

Beds of Eagle Ford(?) age or Tuscaloosa(?) 

formation

Shale, light-gray, micaceous, more 

calcareous than overlying unit; contains siderite pellets (according to 

Spangler, 1950, p. 113). Core 4,595- 

4,605 feet, recovered 3 feet, very pale 

gray, waxy-textured, micaceous shale 

containing Estheriaf sp.; sp gr 2.36. 

Core 4,700-4,710 feet, recovered 14 

inches, light-gray, slightly fossiliferous 

shale; sp gr 2.35. Ostracoda obtained 

from drill-cutting samples in the unit 

are: Bairdia? cf. B. alexandrina Blake 

(4,750-4,760 feet), Cythereis sp. aff. C. 

rugosissima Alexander (4,600-4,610 

feet), Cythereis simulonuda Swain, n. sp. 

(4,780-4,790 feet), Cythereis ornatissima 

(Reuss) (4,640-4,650 feet)________ 4,800 258 

Tuscaloosa(?) formation

Sandstone, shale and limestone, interbedded. Sandstone is white and lightgray, thin to thick bedded, mostly fine 

calcareous, glauconitic, grains angular 

and subrounded, containing oyster shells 

and other fossils, stained with limonite 

4,800-4,820 feet and 5,335-5,355 feet; 

shale is gray, micaceous, calcareous, 

partly glauconitic, chloritic?, silty and 

sandy; limestone is white, coquinoid, 

oyster-bearing, partly sandy, glauconitic, 

stained with limonite 4,945-4,965 feet, 

and 5,150-5,180 feet. Core 4,902-4,905 

feet, recovered 29 inches, medium-gray, 

very sandy, micaceous, chloritic? shale; 

sp gr 2.25. Core 4,991-^,996, recovered 

6 inches, white, fine, angular-grained porous, micaceous, chloritic? sandstone. 

Core 5,294-5,304 feet, recovered 14 

inches, medium-gray, micaceous, silty, 

chloritic? shale; sp gr 2.18. Core 5,254- 

5,264 feet, recovered 5 feet, light-gray, 

fine-grained, calcareous, argillaceous, 

micaceous, chloritic?, sandstone; sp gr 

ranges from 2.54 to 2.56. Core 5,280- 

5,290 feet, recovered 10 feet, light-gray, 

flne-grained, calcareous, argillaceous, 

micaceous sandstone; sp gr ranges from 

2.29 to 2.53. Core 5,399-5,404 feet, recovered 5 feet, light-gray, fine, angulargrained, friable, silty, micaceous, chloritic? sandstone; sp gr 2.03. Cythereis 

simulonuda Swain, n. sp. (5,340-5,350 

feet)__________________—— 5,580 780
64 OSTRACODA FROM WELLS IN NORTH CAROLINA

Upper and Lower Cretaceous Depth TMckneSs 

Beds of Washita(?) age (feet) (feet)

Limestone, white and brown, finely crystalline, sandy, stained with limonite, and 

interbedded gray sandy shale. Core 5,- 

582-5,587 feet, recovered 5 feet, graybrown, silty shale, with scattered quartz 

grains; cavernous structure due to leaching of soluble shell material, cavities 

lined with limonite, sp gr 2.16_____ 5,630 50

Sandstone, white, fine-grained, micaceous, 

calcareous, fossiliferous, chloritic?, 

glauconitic in lower part; and interbedded dark-gray, soft, fissile, finely 

micaceous shale. Core 5,642-5,652 feet, 

recovered 2 feet 6 inches, gray, very 

sandy, calcareous, fossiliferous shale; 

sp gr 2.56. Cytheropteron (Eocytheropteron) aca/udatum Swain, n. sp. (5,- 

640-5,650 feet)________________ 5,675 45 

Lower Cretaceous

Beds of Fredericksburg(?) age

Limestone interbedded with lesser 

amounts of sandstone and shale. Limestone is white, brown and reddish 

brown, finely crystalline, sandy, fossiliferous, partly glauconitic, slightly 

sideritic. Sandstone is light gray, finegrained, calcareous, fossiliferous, 

slightly glauconitic. Shale is dark gray, 

silty, micaceous, sandy, containing a 

little light-gray waxy mudstone in lower 

100 feet. Core 5,733-5,738 feet, recovered 16 inches, light-gray, silty, micaceous, chloritic? shale, with mollusk 

prisms; sp gr 2.27. Core 5,850-5,860 

feet, recovered 15 inches, light-gray, 

very sandy, silty, micaceous, chloritic? 

shale; sp gr ranges from 2.18 to 2.55. 

Core 6,108-6,110 feet, recovered 10 

inches, light-gray, fine, angular-grained, 

slightly silty, porous, micaceous, chloritic? standstone. Cytheropteron (Eocytheropteron) tumidum Alexander 

(5,790-5,800), Apatocythere? leguminoidea Swain, n. sp. (6,040-6,050 feet) __ 6,110 435 

Beds of Trinity (?) and pre-Trinity(?) age 

undifferentiated

Shale, sandstone and limestone, interbedded. Shale is mostly light green and 

contains sandy laminae; sandstone is 

white, fine-grained, calcareous and contains oyster shells; limestone is white 

finely crystalline, sandy, and contains 

oyster shells. Core 6,132-6,137 feet, recovered 5 feet, light gray, fine- and 

medium-grained, argillaceous, calcareous, micaceous sandstone, containing 

oyster shells; sp gr 2.65. Core 6,307- 

6,311 feet, recovered 18 inches, lightgray, fine- and medium-grained, grains 

round and subangular, calcareous, micaceous, chloritic? sandstone; sp gr 2.45. 

Core 6,370-6,373 feet, recovered 3 feet, 

gray clay-shale with laminae of white 

(ashy?), siltstone and white, fineDepth Thickness

Lower Cretaceous—Continued (feet) (feet) 

Beds of Trinity (?) and pre-Trinity (?) age 

undifferentiated—Continued

grained sandstone; sp gr ranges from 

1.90 to 2.23. Cypris? sp. (6,460-6,470 

feet), Ilyocypris? tumida Swain, n. sp. 

(6,350-6,360 feet), Apatocythere? leguminoides Swain, n. sp. (6,350-6,360 

feet), Schuleridea hatterasensis Swain, 

n. sp. (6,300-6,310 feet), Asciocythere 

rotunda (Vanderpool) (6,300-6,310 

feet), Asciocythere? cf. Af amygduloides (Cornuel) (6,250-6,260 feet), 

Asciocythere? triangularis Swain, n. sp. 

(6,430-6,440 feet), Pterygocythereis cf. 

P. toMana (Israelsky) (6,310-6,320 

feet), Cytheropteron (Eocytheropteron) 

tumoides Swain, n. sp. (6,340-6,350 

feet), C. (E.) trinitiensis (Vanderpool) 

(6,170-6,180 feet), Hutsonia? microrugosa Swain, n. sp. (6,260-6,270 feet)_ 6,475 365

Sandstone, white and light-green, fine- and 

coarse-grained above, fine- and mediumgrained below, grains angular and subrounded, partly calcareous, massive. 

Core 6,487-6,497 feet, recovered 10 feet, 

light-gray and white, medium-grained, 

angular-grained sandstone, with abundant snow-white silt; sp gr ranges from 

2.15 to 2.63. Core 6,497-6,507 feet, recovered 9 feet, light-gray and white, fineand medium-grained with grains angular 

and subrounded, slightly calcareous 

t sandstone, containing abundant snowwhite silt, oyster fragments and large 

muscovite flakes; sp gr ranges from 2.16 

to 2.627. Core 6,507-6,512 feet recovered 

5 feet, white, fine- and medium-grained 

very silty sandstone and siltstone; sp 

gr ranges from 2.137 to 2.186. Core 

6,512-6,522 feet, recovered 7 feet 6 

inches, light gray, fine, angular-grained, 

micaceous, chloritic? sandstone; sp gr 

ranges from 2.11 tq 2.14. Core 6,522- 

6,532 feet, recovered 4 feet, light-gray, 

fine- and medium-grained, very silty, friable, micaceous sandstone; sp gr ranges 

from 2.13 to 2.38 feet. Core 6,532^ 

6,542 feet, recovered 3 feet, light gray, 

fine, angular-grained, silty, micaceous 

sandstone; sp gr 2.19. Core 6,542-6,552 

feet, recovered 7 feet, as preceding, but 

argillaceous; sp gr 2.14. Core 6,552- 

6,562, recovered 10 feet, as preceding, 

chloritic?; sp gr ranges from 2.15 to 

2.64. Core 6,562-6,572 feet, recovered 

10 feet, as preceding ; sp gr ranges from 

2.11 to 2.17. Core 6,572-6,581 feet, recovered 7 feet, as preceding, carbonaceous ; sp gr ranges from 2.09 to 2.18. 

Schuleridea hatterasensis Swain, n. sp. 

(6,477-6,482 feet)______________ 6,585 110

Shale, sandstone, and limestone, interbedded. Shale is light grayish-brown, 

texture "papery"; sandstove is white, 

fine and medium grained calcareous;
MESOZOIC OSTRACODA 65

Depth Thickness

Lower Cretaceous—Continued (feet) (feet) 

Beds of Trinity (?) and pre-Trinity (?) age 

un differentiated—Continued

limestone is white, finely crystalline, 

sandy; near top of unit limestones are 

spotted with siderite and limonite. Core 

6,630-6,640 feet, recovered 5 feet, 

light gray, argillaceous, sandy, glauconitic limestone containing oyster 

shells; sp gr 2.45-2.60. Paracypris sp. 

6,700-6,710 feet. Limestone, white and 

• brownish-gray, finely crystalline, partly 

oolitic (around 6,800-6,860 and 6,920 

feet) and phosphatic (at about 6,760 

and 6,850 feet) ; interbedded gray and 

brownish-gray shale with "papery" texture. Core 6,734-6,774 feet, recovered 

10 feet, firm, gray, silty, sandy, very 

micaceous, slightly fossiliferous shale; 

sp gr ranges from 2.34-2.58. Core 6,909- 

6,918 feet, recovered 5 feet, light gray, 

finely sandy, argillaceous, compact, fossiliferous limestone; sp gr ranges from 

2.61 to 2.63. Core 6,918-6,924 feet, 

recovered 6 feet, light gray, dense, 

oyster-bearing limestone containing fine 

sand; sp gr 2.63. Apatoeytliere? lanceolata Swain, n. sp. 6,930-6,490 feet____ 6, 935 201

Shale, gray-green and brownish-gray in 

upper part, with red and purple beds 

in lower part; contains thin layers of 

white, finely crystalline limestone and 

of white, fine-grained angular sandstone 

with pink silty grains___________ 7, 018 83

Sandstone, white with grains fine to coarse 

and angular to rounded, partly calcareous, in thick beds, containing layers of 

green shale in lower 75 feet; interbedded 

white, finely crystalline, fairly porous, 

slightly oolitic limestone at several 

levels, notably from 7,220-7,240 feet and 

7,295-7,305 feet. Core 7,021-7,026 feet, 

recovered 25 inches, light-gray, dense, 

finely crystalline, sandy, oyster-bearing 

limestone with argillaceous pockets; sp 

gr ranges from 2.09 to 2.304. Core 7,- 

034-7,039 feet, recovered 32 inches, light 

gray, fine-grained, porous, angulargrained, slightly silty sandstone; sp gr 

ranges from 2.17 to 2.23. Core 7,076- 

7,081 feet, recovered 4 feet, light gray, 

fine-grained, porous, angular-grained, 

slightly calcareous sandstone with waxy 

clay; sp gr ranges from 2.23 to 2.65. 

Core 7,081-7,091 feet, recovered 4 feet, 

light-gray to white, porous, recrystallized, micaceous, sandy, oyster-bearing 

limestone; sp gr ranges from 2.28 to 

2.42. Core 7,091-7,096 feet, recovered 2 

feet 6 inches, white, fine-grained, angular-grained, silty, friable sandstone; sp 

gr 2.205. Core 7,096-7,106 feet, light 

gray, fine-grained, angular-grained, 

porous, slightly silty, argillaceous, chloritic?, micaceous sandstone; sp gr ranges 

from 2.19 to 2.21. Core 7,106-7,113 feet,

Depth Thickness

Lower Cretaceous—Continued (feet) (feet) 

Beds of Trinity (?) and pre-Trinity (?) age 

undifferentiated—Continued

recovered 7 feet, light gray, fine-grained, 

angular-grained, porous, slightly argillaceous, micaceous, chloritic?, sandstone; 

sp gr 2.14. Core 7,113-7,123 feet, recovered 9 feet, sandstone as above ; sp gr 

2.11. Core 7,123-7,133 feet, recovered 10 

feet, sandstone as above, calcareous; sp 

gr ranges from 2.12 to 2.42. Core 7,191- 

7,201 feet, recovered 10 feet, light gray, 

fine-grained, angular-grained, very argillaceous sandstone; sp gr ranges from 

2.09 to 2.16. Core 7,234-7,238 feet, recovered 2 feet, medium gray, micaceous 

shale containing microfossils; sp gr 

ranges from 2.60-2.67. Core 7,316-7,326 

feet, recovered 10 feet, light gray, finegrained, very argillaceous, friable, micaceous, chloritic? sandstone; sp gr 

ranges from 2.105 to 2.32. Core 7,326- 

7,336 feet, recovered 8 feet, light gray, 

fine-grained, angular-grained, silty, 

fairly porous, micaceous, chloritic? sandstone; sp gr 2.32. Core 7,400-7,410 feet, 

recovered 5 feet, light gray, drab, very 

finely sandy shale with laminae of siltstone; sp gr 2.23. Cythereis sp. aff. C. 

fredericksburgensis Alexander 7,310- 

7,320 feet_____________—__— 7, 430 412

Shale, light- and dark-gray, fissile; greenish gray in lower 50 feet; light gray, 

fine- to medium-grained calcareous sandstone 7,585-7,610 feet. Core 7,503-7,510 

feet, recovered 3 feet 6 inches, dark-gray, 

compact, sandy, micaceous shale, sp gr 

2.49. Core 7,594-7,602 feet, recovered 3 

feet, 6 inches, light-gray, compact, sandy 

shale with lenticular pockets of finegrained, argillaceous sandstone; sp gr 

ranges from 2.35 to 2.49. Core 7,658- 

7,664 feet, recovered 4 feet, light gray, 

very finely sandy shale; sp gr ranges 

from 2.405 to 2.49. Cytherelloidea 

darensis Swain, n. sp. 7,500-7,510 feet, 

Apatocythere? tumidosa Swain, n. sp. 

7,640-7,650 feet________________ 7,665 235

Sandstone, white, grains fine to coarse in 

upper part, fine to medium below, and 

angular to subrounded; slightly calcareous, thick-bedded. Core 7,705-7,715 

feet, recovered 10 feet, light-gray, finegrained, silty, micaceous sandstone; sp 

gr ranges from 2.30 to 2.31________ 7, 758 93

Limestone and shale, interbedded. Limestone is light gray to white, finely crystalline, oolitic and phosphatic? at several levels, partly fossiliferous, in units 

up to 50 feet thick. Shale is gray and 

gray brown, fissile. Both shale and 

limestone are sandy and contain a little 

interbedded light-gray, fine- and medium-grained calcareous sandstone in 

lower 75 feet. A unit of sandy siltstone 

occupies upper 30 feet of the unit. Core
66 OSTRACODA FROM WELLS IN NORTH CAROLINA

Depth Thickness

Lower Cretaceous—Continued (feet) (feet) 

Beds of Trinity (?) and pre-Trinity (?) age 

undifferentiated—Continued

7,766-7,776 feet, recorered 6 feet 6 

inches, light gray, sandy, micaceous siltstone; sp gr ranges from 2.38 to 2.43. 

Core 7,945-7,959 feet, recovered 2 feet, 

medium-gray sandy fossiliferous shale, 

sp gr 2.64. Monoceratinal sp. 8,200- 

8,210 feet___________________ 8,240 518

Sandstone, light gray and white, fine- to 

coarse-grained, conglomeratic in lower 

50 feet, angular-grained, partly chloritic?, slightly feldspathic at several 

levels; interbedded gray, silty, fissile 

shale, and in lower 75 feet a little tan 

oolitic limestone. Gomphcytherel cf. 

G. silvana Martin, 8,430-8,440 feet. Macrod&ntinal obliqua Swain, n. sp. 8,330- 

8,340 feet___________________ 8,500 260 

Upper Jurassic (?).

Beds of Schuler (?) age

Dolomite, light-brown, sandy, coarsely 

crystalline, cavernous; tan, partly dolomitized, oolitic limestone in middle 

part —_______——________ 8, 585 85

Sandstone, light gray and white, finegrained to conglomeratic, in part ferruginous and with nodular siderite; interbedded green and greenish-gray fissile 

shale and mudstone; brown, dense, conglomeratic, oolitic limestone from 8,750- 

8,770 feet___________________ 8, 750 165

Limestone, gray, dense, with a thin unit of 

brown, porous dolomite at top; a little 

interbedded gray calcareous shale. Core 

8,763-8,768 feet, medium-gray, well-indurated, calcareous, fossiliferous shale 

and shaly limestone, sp gr 2.66_____ 8, 780 30

Limestone, gray, dense, sandy and conglomeratic, dolomitic and oolitic in 

upper part; a layer of white sugary 

anhydrite 8,799-8,800 feet; lower 20 to 

30 feet consists of light-gray, finegrained, silty, argillaceous, calcareous 

sandstone—________________ 8, 880 100

Shale, light- and dark-gray and greenishgray, sandy, partly carbonaceous, 

and pyritic, containing echinoid spines 

and poorly preserved ostracodes. Core 

8,917-8,922 feet, recovered 5 feet, darkgray, compact, sandy, micaceous, fossiliferous shale, sp gr 2.61_________ 8, 980 100

Limestone, light and dark gray and brown, 

dense, argillaceous, partly oolitic limestone containing quartz pebbles in 

middle and lower parts, sandy in lower 

part; a little interbedded dark-gray, 

silty, indurated shale; white, slightly 

feldspathic, quartz conglomerate 9,100- 

9,110 feet. Core 9,115-9,116 feet, darkgray argillaceous, conglomeratic, fossiliferous limestone with Schuleridea cf. 

8. pentagonalis Swartz and Swain, and 

the foraminifer Choffatella sp., sp gr 

2.67. Asciocythere"! leguminoides

Upper Jurassic (?)— Continued Depth Thickness 

Beds of Schuler (?) age—Continued (feet) (feet) 

Swain, n. sp., 9,030-9,040 feet; Schuleridea cf. 8. acuminata Swartz and 

Swain, 9,100-9,110 feet_______—— 9,150 210 

Conglomeratic sandstone and arkose. 

Above 9,475 feet sandstones are white 

and light gray, coarse-grained, conglomeratic, feldspathic, partly calcareous and are interbedded with gray, 

green, and red sandy shale. Below 

9,475 feet sandstones are white or red 

and pink due to hematite coloring, arkosic, conglomeratic, and are interbedded 

with red and green sandy mudstone. 

Feldspar grains in red and pink sandstones, are reddish and kaolinic; in 

white sandstones, feldspars are fresh in 

appearance. Core 9,231-9,241 feet, recovered 9 feet 6 inches; top 3 feet 6 

inches, light-gray, fine-grained, calcareous, argillaceous sandstone, bottom 6 

feet, white fine- to medium-grained silty 

sandstone with pink grains; sp gr ranges 

from 2.30 to 2.57. Core 9,241-9,251 feet, 

recovered 18 inches, light-gray and pink, 

grains very coarse sand to fine conglomeratic sizes and subangular to subrounded, feldspathic. Core 9,251- 

9,261 feet, recovered 7 feet; top 2 feet, 

light-gray, very coarse-grained, porous, 

angular-grained, feldspathic sandstone; 

bottom 5 feet, medium- and greenishgray, compact, sandy, micaceous shale; 

sp gr ranges from 2.56 to 2.59. Core 

9,261-9,271 feet, recovered 3 feet, light 

greenish-gray and red, very sandy, compact, micaceous, chloritic? shale and 

agrillaceous sandstone; sp gr 2.58. Core 

9,271-9,281 feet, recovered 3 feet, lightgray, medium- to coarse-grained and 

finely conglomeratic, feldspathic, very 

silty sandstone. Core 9,281-9,291 feet; 

recovered 7 feet 6 inches; top 3 feet 6 

inches medium-gray, medium- to coarsegrained, very shaly, micaceous, feldspathic sandstone; bottom 4 feet, gray, 

waxy, sandy, conglomeratic, feldspathic 

shale, and coarsely conglomeratic, feldspathic sandstone; sp gr 2.54. Core 

9,291-9,298 feet, recovered 5 feet, white, 

fine- to coarse-grained and finely conglomeratic, very silty sandstone containing snow-white silt. Core 9,298- 

9,308 feet, recovered 6 feet, white, fineto coarse-grained and finely conglomeratic, subrounded- to angular-grained, 

slightly feldspathic sandstone. Core 

9,510-9,515 feet, recovered 3 feet, darkred and green compact, sandy, shale; 

sp gr 2.58___________________ 9, 878 728 

Pre-Cambrian

Granitic igneous rock, greenish-gray, 

stained red by hematite in upper 75 feet, 

medium- to coarse-grained, chloritic; 

highly fractured and containing calcite
MESOZOIC OSTRACODA 67

Upper Jurassic (?)-Continued Depth Thickness 

Pre-Cambrian—Continued (feet) (feet) 

fracture-fillings; of syenitic or monzonitic composition in upper part, becoming more quartzose below. Core 9,876- 

9,882 feet, recovered 5 feet, reddishbrown and light-green granitic igneous 

rock, with considerable kaolinite? Core 

9,912-9,921 feet, recovered 1 foot 6 

inches, reddish and greenish-gray, fractured, medium- to coarse-grained, chloritic, kaolinitic? granitic igneous rock; 

sp gr 2.65. Core 9,941-9,943 feet, recovered 3 inches, granitic igneous rock 

as above—_——______________ 10,054 176

MESOZOIC BOCKS IN ESSO STANDARD OIL CO. NORTH 

CAROLINA ESSO WELL NO. 2

Upper Cretaceous ^^ Thlckness 

Peedee (?) formation (feet) (feet)

Sandstone, green and greenish gray, 

coarse-grained, sideritic, poorly consolidated. Spangler (1950, p. 112) reported 

Glo^otruncana area, (Cushman) at approximately 2,275 feet—____ 2, 224-2, 280 50

Shale, light-gray and brown, silty and 

marly, glauconitic; with thin beds of 

medium-grained sandstone. Brachycythere arachoides (Berry) 2,310-2,320 

feet; Cythereisf pamlicoensis Swain, n. 

sp,, 2,310-2,320 feet; Krithe cf. K. postprojecta Schmidt, 2,300-2,310 feet___ 2,380 100 

Black Creek (?) formation

Shale, light-gray, marly, with thin beds 

of medium-grained sandstone. Haplocytheridea monmouthensis (Berry), 2,750- 

2,760 feet; Brachycythere nausiformis 

Swain, n. sp., 2,750-2,760 feet; Cythereis 

qwdrialira Swain, n. sp. 2,750-2,760 feet. 

Inoceratnus prisms occur at 2,400-2,410 

feet and below. Spangler (1950, p. 113) 

reported Planulina taylorensis (Carsey) 

at approximately 2,400 feet; Kyphopyxa 

christneri (Carsey) at approximately 

2,460 feet, and Vaginulina regina Plummer (=F. texana Cushman) at approximately 2,600 feet___________ 2,760 380 

Beds of Eutaw (?) age

Conglomeratic sandstone, -light-gray and 

white, poorly consolidated, partly glauconitic and containing chert pebbles in 

upper part, fragments of oyster shells 

and other molluscs_______________ 2, 870 110

Sandstone, fine- and medium-grained, glauconitic in upper part, reddish at about 

2,950 feet, with considerable interbedded 

gray micaceous shale from 3,000 to 3,225 

feet; containing abundant oyster shell 

fragments throughout——————————— 3,285 415

Shale and limestone, interbedded. Shale 

is gray, micaceous; and contains abundant oyster shells. Limestones are gray 

oyster-shell coquinas, in part mottled 

with hematitic clay, are mostly in thin 

beds, and are most numerous in lower 

two-thirds of unit__—————————— 3,515 230

Upper Cretaceous—Continued Depth Thickness 

Beds of Eagle Ford (?) age (feet) (feet)

Shale, gray, micaceous, containing abundant oyster shells below 3,575 feet and 

spherulites of siderite in middle part__ 3, 718 202

Limestone, white, sandy, glauconitic, fossiliferous, stained by hematite near 

top; with thin beds of gray shale and 

fine-grained, light-gray, glauconitic and 

chloritic? sandstone____________ 3,795 77

Shale, gray, micaceous, slightly glauconitic and sideritic, containing oyster 

shells __________—_________ 3,890 95 

Tuscaloosa (?) formation

Sandstone, interbedded with shale and a 

little limestone. Sandstone layers are 

white to light gray, partly calcareous, 

carbonaceous, and sideritic, and contains conglomeratic layers from 3,910- 

3,925 feet, 4,025-4,060 feet, 4,170-4,180 

feet, 4,320-4,340 feet, and 4,750-4,760 

feet; partly glauconitic in upper part. 

Shales are gray, sandy, micaceous, carbonaceous, chloritic?, and are interlayered with pale-gray, green, red and 

brown mudstones. White, fossiliferous 

limestone beds occur from 4,490-4,510 

feet and 4,770-4,785 feet. Oyster shells 

occur at many levels throughout the 

unit ______________________ 4,923 1,033 

Lower Cretaceous

Beds of Trinity (?) and pre-Trinity (?) age 

undifferentiated.

Shale, with thick beds of sandstone, and 

lesser amounts of limestone. Shales 

are mostly gray and greenish-gray 

carbonaceous mndstones, with layers 

of dark-gray fissile shale and of red 

shale at several levels. Oyster shells 

occur at several horizons. Sandstones 

are mostly fine-grained, light-gray and 

white, calcareous; the most prominent 

beds occur from 5,040-5,087 feet, 5,155- 

5,170 feet, 5,217-5,240 feet, and 5,455- 

5,495 feet. Limestones are white and 

gray, dense, and contain oyster shells; 

most prominent layers are from 4,950- 

4,970 feet, 5,010-5,015 feet, 5,110-5,122 

feet, 5,255-5,260 feet, and 5,330-5,340 

feet. Schuleridea? lacustris Swain, 

n. sp. 4,970-4,980 feet; Schuleridea 

hatterasensis Swain, n. sp., 5,330-5,340 

feet _____________________ 5,495 572 

Limestone, white, light- and dark-gray 

and brown, soft and weathered in upper 

10 feet, finely crystalline, sandy near top 

and bottom, partly oolitic and pseudooolitic (phosphatic?), fossiliferous, and 

with thin layers of white, sugary anhydrite in lower 50 feet; beds of light and 

dark gray and brown, fissile shale. 

Apatocytheref lanceolata Swain, n. sp. 

5,520-5,530 feet, ApatocytJieref tumidosa Swain, n. sp., 5,520-5,530 feet—— 5, 718 223
68 OSTRACODA FROM WELLS IN NORTH- CAROLINA

Depth Thickness

Lower Cretaceous—Continued (feet) (feet) 

Beds of Trinity (?) and pre-Trinity (?) age 

undifferentiated—Continued

Shale, gray and brownish-gray, soft, 

fissile, with layers of varicolored mudstone in lower part; beds of white, finely 

crystalline, slightly porous, recrystallized limestone 5,795-5,840 feet, and 

white, fine-grained, calcareous, argillaceous sandstone 5,890-5,925 feet_____ 5, 980 262

Limestone, white and light-gray, finely 

crystalline, fossiliferous, in part oolitic 

and phosphatic?, cavernous; and interbedded gray, fissile shale_________ 6,118 138

Shale and sandstone, interbedded. Shale 

is mostly green, waxy-textured mudstone 

containing Atopochara sp.; a little gray 

fissile shale from 6,370-6,400 feet. Sandstone is white, fine-grained, slightly 

calcareous, chloritic?, and with spherulitic siderite; most conspicuous unit of 

sandstone is from 6,185-6,265 feet__ 6,410 292

STRATIGRAPHIC DISTRIBUTION OF THE OSTRACODA

The stratigraphic distribution of the ostracode species described in this paper is given in the table below. 

Only the highest occurrences of species obtained from 

well samples are recorded in the table, except for a few 

instances where the presence of the species at a deeper 

level seems reasonably certain. The specimens obtained from core samples have been recorded as occurring within the zone cored.

SYSTEMATIC DESCRIPTIONS

Order PLATYCOPA Sars, 1865

Family CYTHERELLIDAE Sars, 1865

Genus CYTHERELLA Jones, 1849

Cytherella navarroensis Alexander

Plate 8, figure 1

Cytherella navarroensis Alexander, 1929, Texas Univ. Bull. 2907, 

p. 63, pi. 2, figs. 1, 2.

Shell elongate-subovate in lateral view; greatest 

height slightly anterad of midlength; dorsal margin 

moderately convex, strongly truncate posterior to position of greatest height; ventral margin nearly straight, 

passing with broad curvature into anterior margin and 

with narrower curvature into posterior margin; anterior margin broadly and uniformly rounded; posterior 

margin more narrowly rounded. Eight valve overlapping and extending beyond left around entire 

periphery; greatest extension mid-dorsal and in anterior half of shell.

A low, broad, dorso-ventrally elongated swelling 

occupies a position just posterior to midlength and 

marks area of greatest convexity. A low ridgelike 

swelling borders posterior margin of right valve; corresponding feature not clearly exhibited on left valve. 

Surface smooth. Internal features not observed.

Length of figured specimen 0.78 mm, height 0.49 mm, 

thickness 0.35 mm.

Remarks: Alexander (1929, p. 53) pointed out that 

this species may be distinguished from C. austinensis 

Alexander by its stronger mid-dorsal and ventral right 

valve overlap and more pronounced truncation of the 

dorsal marginal slopes. The present example has the 

external characteristics prescribed for C. na/vwrroensis, 

but the internal features have not been observed.

Occurrence: Hatteras Light Well no. 1, 3,240-3,250 

feet, Black Creek formation, U.S.N.M. 106906. In 

northeastern Texas the species has been found most 

commonly in the Navarro group, but also occurs rarely 

in the upper part of the underlying Taylor marl 

(Alexander, 1929, p. 53).

Cytherella cf. C. obesa Alexander 

Plate 8, figure 2

Ct/tJiereUa obcsa. Alexander, 1929, Texas Univ. Bull. 2907, p. 51, 

pi. 1, figs. 3, 6.

Shell ovate in lateral view; greatest height median; 

dorsal margin moderately convex; ventral margin 

slightly convex; anterior margin broadly and uniformly 

rounded; posterior margin a little more narrowly 

rounded and slightly truncate above midheight. Right 

valve much larger than left, overlapping and extending 

beyond the other around entire periphery; greatest extension dorsal and ventral. Valves moderately convex 

with greatest thickness in posterior half. Surface 

smooth. Internal features not observed.

Length of figured specimen 0.94 mm, height 0.62 mm, 

thickness 0.45 mm.

Remarks: The present example is more uniformly 

rounded anteriorly and slightly less convex ventrally 

than the form figured by Alexander, but otherwise is 

similar to it. C. ovoidea Alexander exhibits lesser 

convexity of the valves and greater dorsal and ventral 

extension of the right valve beyond the margin of the 

left than does the present species.

Occurrence: Hatteras Light well No. 1, 3,130-3,140 

feet, Peedee (?) formation, U.S.N.M. 106907. In 

northeastern Texas C. obesa occurs in the upper part 

of the Taylor marl (Alexander, 1929, p. 51).

Genus CYTHERELLOIDEA Alexander, 1929

Cytherelloidea darensis Swain, n. sp.

Plate 8, figure 3

Shell subelliptical in lateral view, dorsal and ventral 

margins nearly straight, both slightly concave medially; terminal margins rounded, anterior somewhat 

broader than posterior; anterodorsally, margin of right 

valve somewhat elevated as a small shoulder. Right 

valve larger than left, but extends beyond the other 

conspicuously only in anterodorsal region.
MESOZOIC OSTRACODA 69

Stratigraphic distribution of the Ostracoda described in this paper

Species

Cytherellidae:

Cytherella cf . C. obesa Alexander _ _ _ _

Cytherelloidea darensis, n. sp _ _

Cypridae:

Paracypris sp _ _ _

Bairdiidae: 

Bairdia? cf. B. alexandrina Blake. -

Bairdoppilata pondera Jennings _

Bairdiocypris? sp _ _ _ ___ ___

Cytheridae:

Schuleridea hatter asensis, n. sp__

Schuleridea? lacustris, n. sp _ _

Schulendea cf. S. pcntagonalis Swartz

Schuleridea cf. 8. acuminata Swartz

Asciocytheref cf. A.f amygdaloides 

(Cornuel) _______ ______ _ _____

Haplocytheridea? graysonensis (Alexander) _ _ _ _ _..___ ____ _ __

Haplocytheridea? sp. aff. H? plummeri

Cythereis sp. aff. C. rugosissima (Alexander) _ _ _ ___ __ ___ _ ____ _

Cythereis sp. aff. C. fredericksburgensis

Pterygocytherei's cf. P. tokiana (IsraelO\7-\7\

Cytheropteron (Eocytheropteron)

Cytheropteron (Eocyfheropteron)

Cytheropteron (Eocytheropteron)

Monoceratina sp. aff. M. semiornata

Macrodentinaf obliqua, n. sp _____

Schuler(?) 

age

V

V

<*V

Trinity(?) 

and preTrinity(?) 

age

X

v

X

V

X

V

v

X

X

X

v

v

v

0)

v

C1)

v

v

v

X

X

Fredericksburg(?) 

age

0)

v

Washita(?) 

age

0)

v

Tusealoosa(?) formation

(0

v

v

Eagle 

Pord(?) 

age

X

X

v

X

X

X

X

X

Eutaw(?) 

age

X

X

X

0)

X

X

X

X

X

Black 

Creek (?) formation

X

X

X

X

X

X

X

X

X

C)

X

Peedee(?) formation

X

X

X

X

1 Occurrence in doubt as specimens may have caved from higher levels.
70 OSTRACODA FROM WELLS EST NORTH CAROLINA

Terminal margins each provided with a row of small 

spines; anterior margin bears a narrow elevated rim. 

A narrow ridge rises near postdorsal marginal bend, 

trends anteriorly and ventrally and dies out about onethird from anterior end. A second narrow longitudinal ridge rises about one-fifth from anterior end, trends 

posteriorly to slightly postrad of midlength where it 

bends toward dorsum, extends to a position just ventrad 

of postdorsal marginal bend and terminates in a high, 

somewhat elongated, blunt node. A third, more ventral, longitudinal ridge rises about one-fourth from 

anterior end, continues posteriorly approximately to 

midlength where it jogs slightly toward dorsum and 

terminates in a small node near posterior margin. A 

shallow, rounded, median depression lies between dorsal 

and median longitudinal ridges. Surface coarsely 

pitted, but partly obscured by matrix in holotype. Internal features not observed.

Length of holotype 0.57 mm, height 0.31 mm, thickness 0.22 mm.

Relationships: In its pitted surface and prominent 

posterior nodes this form resembles O. granulosa 

(Jones) as identified by Alexander (1929, p. 58) from 

the Grayson formation of Texas and C. reticulata Alexander from the Weno and Denton formations of Texas. 

In both of the latter species, however, there are only 

two longitudinal ridges, and the dorsal posterior node 

is connected to a ridge lying near the dorsum rather 

than to a more median ridge as in the present species. 

O. howei Swain (1948, p. 191) from the subsurface 

Eocene of Maryland has a similar number and arrangement of longitudinal ridges, but they are broader than 

in the present species. C. castleberryensis Howe and 

Law (1936, p. 20) from the Byram marl, Oligocene, of 

Mississippi is pitted, and has a spinose anterior margin 

as does the new species, but has only two high longitudinal ridges, and bears other short longitudinal ridges 

in median and ventral areas.

Occurrence: Hatteras Light well No. 1, Dare County, 

N. C., 7,500-7,510 feet, beds of Trinity (?) and preTrinity (?) age, undifferentiated, U.S.N.M. 106908.

Order PODOCOPA Sars, 1865

Family CYPRIDAE Baird, 1846

Genus CYPBJS Miiller, 1776

Cypris? sp. 

Plate 8, figure 4

Left valve subovate in lateral view; greatest height 

about one-third from anterior end; dorsal margin 

moderately arched; ventral margin nearly straight to 

slightly concave medially; anterior margin rounded, 

extended below; posterior margin narrowly rounded, 

most extended a little belo.w midheight. Valve strongly

convex in ventral half; swollen ventral surface overhangs margin.

Surface periphery ornamented by fine concentric 

ridges; medial portion bears similar ridges arranged 

more or less longitudinally.

Internal features concealed by matrix.

Length 1.00 mm, height 0.49 mm, thickness of left 

valve 0.39 mm.

Remarks: In general outline this form is related 

to Cypris Miiller. Its concentric ornamentation, its 

general shape, and its strongly convex ventrum are 

reminiscent of Cytheropteron concentricum (Reuss), 

and particularly of O. concentricum mrginea (Jones) 

from the Cretaceous of Europe, but the present form 

does not have the ends strongly compressed. Lack of 

knowledge concerning the internal features of the present specimen prevents its certain classification.

Occurrence: Hatteras Light well No. 1, 6,460-6,470 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106909.

Genus PARACYPRIS Sars, 1865

Paracypris sp.

Plate 8, figure 7

Shell sublanceolate in side view; greatest height 

about median; dorsal margin moderately arched; 

ventral margin nearly straight, slightly concave medially; anterior margin broadly rounded; posterior 

margin narrowly rounded, strongly extended ventrally. 

Left valve larger than right, extending beyond the 

other around entire periphery. Valves moderately 

convex, greatest convexity median. Surface of single 

specimen at hand poorly preserved but probably was 

smooth. Internal features not observed.

Length 0.73 mm, height 0.33 mm, thickness 0.24 mm.

Remarks: This form can not be definitely placed in a 

described species. It is less elongate and less acuminate 

posteriorly than most species of Paracypris. The poor 

preservation of the present specimen and the lack of 

information about the internal features prevent more 

exact classification.

Occurrence: Hatteras Light well No. 1, 6,700-6,710 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106911.

Genus ILYOCYPRIS Brady and Norman, 1889 

Ilyocypris? tumida Swain, n. sp.

Plate 8, figures 5, 6

Shell subelliptical in lateral view; hinge margin 

nearly straight, hinge, a little more than half of shell 

length; ventral margin nearly straight and subparallel 

to dorsum, slightly concave medially; anterior margin 

rounded, subtruncate above; posterior margin more 

uniformly and broadly rounded. Left valve larger
M1SOZOIC OSTRACODA 71

than right; greatest extension beyond right is in dorsal 

and posterior regions. Convexity of valves moderate, 

greatest thickness slightly posterior to midlength.

A shallow, broad, oblique sulcus occurs anterodorsally in each valve and is separated from margin of 

valve by a low but distinct eye-lobe. Anterior end of 

each valve strongly compressed as a distinct marginal 

border. General surface coarsely pitted; the surface of 

the holotype is abraded, but there is a suggestion of 

minute secondary pitting; this may be the result of recrystallization of the shell material.

Internal features not observed.

Length of holotype 0.87 mm, height 0.45 mm, thickness 0.37 mm.

Relationships: This species differs from typical members of Ilyocypris in having only one dorsal sulcus 

rather than two, and in having the anterior end strongly 

compressed, but the subelliptical outline, straight hinge 

and pitted surface, in addition to the conspicuous sulci, 

ally it to Ilyocypris. Several species of middle Mesozoic ostracodes referred to Metacypris Brady, particularly M. ventrosa Swain (1946) from the nonmarine 

Upper Jurassic of Brazil are similar in shape and 

ornamentation to the present species. However, the 

typical metacyprids are more convex even in male 

dimorphs, the sulci are narrower, and the anterior end 

is not strongly compressed. In most metacyprids the 

larger sulcus (in species that bear two) is farther back 

than the sulcus of the new species.

Occurrence: Hatteras Light well No. 1, 6,350-6,360 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated U.S.N.M. 106910. A closely similar 

species occurs in the Schuler formation, Upper Jurassic of Louisiana (Swain, 1949, pi. 3, fig. 30).

Family BAIKDIIDAE Sars, 1887

Genus BAIRDIA Me Coy, 1862

Bairdia? cf. B. alexandrina Blake

Plate 8, figure 13

Bairdia subdeltoidea (Minister), Alexander, 1927, Jour. Paleontology, vol. 1, pp. 29-33, pi. 1.

Alexander 1929, Univ. Texas Bull. 2907, p. 61, pi. 3, fig. 5. 

(Not) Miinster, 1830, Neues Jahrbuch f. Min. u. Geol. p. 64. 

Bairdia alexandrina Blake, 1931, Jour. Paleontology, vol. 5, 

p. 162.

Shell subtriangular in lateral view; greatest height 

slightly anterad of midlength; dorsal margin very 

strongly arched, obtusely angled at position of greatest 

height in left valve; anterodorsal slope of left valve 

forms an angle of about 40° with a line tangent to apex 

of dorsum and parallel to greatest length; postdorsal 

slope forms an angle of about 35° with such a line. 

Ventral margin of left valve moderately convex, that 

of right valve sinuous, concave medially. Anterior 

margin narrowly rounded, posterior margin acuminate,

strongly extended, caudate. Left valve larger than 

right, extending strongly beyond the other dorsally and 

ventrally, less strongly anteriorly; posteriorly, overlap 

not noticeable. Surface sparsely and weakly pitted. 

Internal features not observed.

Length of figured specimen 1.18 mm, height 0.76 mm, 

thickness 0.60 mm.

Remarks: The present form evidently is conspecific 

with that figured and described by Alexander (1929, 

p. 61, pi. 3, fig. 5) as B. subdeltoidea (Munster). Blake 

(1931, p. 162) considered B. subdeltoidea to be a Tertiary species and renamed Alexander's example B. 

alexandrina; but did not demonstrate it to be different 

from B. subdeltoidea. The validity of B. alexandrina 

Blake might be doubted except that Howe (1934, p. 

388) figured and described a specimen believed to represent typical B. subdeltoidea that is of different shape 

than B. alexandrina. Howe's specimen is less strongly 

arched dorsally, less extended posteriorly, and more 

convex ventrally than B. alexandrina.

The generic assignment of the species is tentative 

because the internal features are unknown.. If the 

dorsal slopes are found to contain denticulations, it 

will be necessary to transfer the species to Bairdoppilata Coryell, Sample, and Jennings.

Occurrence: In Texas the species has been found only 

in the Eagle Ford shale (Alexander, 1929, p. 61). The 

figured example is from the Hatteras Light well No. 1, 

4,750-4,760 feet, and its highest observed occurrence 

in that well is 4,470-4,480 feet, beds of Eagle Ford(«) 

age, U.S.N.M. 106916.

Genus BAIRDOPPILATA Coryell, Sample, and Jennings, 1935

Bairdoppilata pondera Jennings

Plate 8, figures 8-12

Bairdoppilata pondera Jennings, 1936, Bull. Am. Paleontology,

vol. 23, No. 78, p. 45, pi. 6, fig. 9.

Schmidt, 1948, Jour. Paleontology, vol. 22, p. 408, pi. 61, 

figs. 21, 22.

Shell subtriangular in lateral view; greatest height 

slightly anterad of midlength; dorsal margin strongly 

convex, obtusely angulate at position of greatest height 

in left valve; anterodorsal slope of left valve forms an 

angle of approximately 40° with a line tangent to position of greatest height and parallel to greatest length; 

posterodorsal slope forms an angle of approximately 

30° with such a line. Ventral margin of left valve 

moderately convex, of right valve sinuous, concave 

medially; anterior margin narrowly rounded and extended just ventrad of midheight; posterior margin 

acuminate and strongly extended below midheight. 

Left valve much larger than right extending strongly 

beyond the other dorsally and ventrally, less strongly 

at ends. Valves rather strongly convex, greatest thickness slightly anterad of midlength. Surface bears

961964—52-
72 OSTRACODA FROM WELLS IN NORTH CAROLINA

scattered, small, inconspicuous pits that mark external 

openings of pore canals.

Hinge ot right valve consists of a groove in the 

rather broad hinge face, into which fits a corresponding 

ridge on left valve. Inner lamellae rather broad, line of 

concrescence and inner margin nearly coincide. Muscle 

scar not observed; according to Schmidt (1948, p. 408) 

the muscle scar consists of about 10 spots: 7 large 

irregularly disposed spots, and 3 smaller ones.

Length of a figured specimen (plate 8, figure 8) 1.04 

mm, height 0.73 mm, thickness 0.54 mm.

Occurrence: Hatteras Light well No. 1, 3,410-3,420 

feet, Black Creek formation and below, U.S.N.M. 

106912-106915. The species also occurs in the Mount 

Laurel and Navesink formations of New Jersey (Jennings, 1936), and with Ewogyra cancel!ata in the Mount 

Laurel sand of Delaware and New Jersey (Schmidt, 

1948).

Genus BAIRDIOCYPRIS Kegel, 1931 

Bairdiocypris? sp.

Plate 8, figure 14

Shell subtriangular in lateral view; greatest height 

about median; dorsal margin strongly arched with 

posterior slope steeper than anterior; ventral margin 

of left valve slightly convex, of right valve nearly 

straight; anterior margin broadly rounded, extended 

below midheight; posterior margin acuminately 

rounded, strongly extended below. Left valve larger 

than right, the umbonate midportion of dorsum extending strongly beyond the flattened hinge-section of right 

valve. Valves not strongly convex, greatest thickness 

median. Surface of present specimen poorly preserved 

but probably was smooth originally. Internal features 

unknown.

Length 0.67 mm, height 0.46 mm, thickness 0.33 mm.

Remarks: In its general outline, umbonate left valve 

and lack of anterodorsal sulcus this form is closely 

related to Bairdiocypris Kegel particularly B. morrisonensis Both. It differs from Schuleridea Swartz 

and Swain in the lack of an anteromedian sulcus and in 

the shortness of the hinge. The single specimen at 

hand is poorly preserved, making establishment of 

a new species inadvisable.

Occurrence: Hatteras Light well No. 1, 7,910-7,920 

feet, beds of Trinity (?) and p re-Trinity (?) age, undifferentiated U.S.N.M. 106917.

Family CYTHERIDAE Baird, 1850 

Genus APATOCYTHERE Triebel, 1940

The following description is adapted from Triebel 

(1940, p. 169) :

Shell of medium size; subtriangular in lateral view; anterior margin broadly rounded; posterior margin more narrowly rounded. Left valve larger than right, overlapping 

it around entire periphery, greatest extension of left is along 

dorsal and ventral margins. Greatest convexity approximately

median. Surface lacks coarse ornamentation; it is either 

smooth or finely punctate. Eye tubercle weakly developed, 

bordered by a shallow sulcus.

Anterior inner lamellae broadest anteriorly, pierced by 

numerous, closely spaced simple radial canals which are curved 

strongly upward in the dorsal third of anterior end; inner 

margin and line of concrescence coincide. Muscle scar consists of a vertical row of four small spots and larger spot in 

front.

Hinge of right valve consists of an anterior rounded tooth, 

an interterminal bar, and a posterior elongate tooth, none of 

which exhibits crenulations. Hinge elements situated beneath 

the dorsal margin and separated from it by rabbet-shelf. Hinge 

of left valve consists of an anterior rounded socket, an interterminal groove and a posterior elongate socket, all defined 

dorsally by an overhang of margin. Between hinge and dorsal 

marginal line occurs a more or less well developed accommodation groove (Ausweichfurche). The selvage in both valves lies 

near the outer margin and parallel with it. Midportion of ventral margin of right valve broadened and separated from outer 

surface of shell by a strongly developed outer ridge (Ausenleiste). Relatively elongate specimens, probably male dimorphs, 

occur with comparatively short and rounded female shells.

Type species: Apatocythere simulans Triebel (1940, 

p. 169).

Occurrence: Lower Cretaceous and Upper Cretaceous (?).

Remarks: This genus is close to Haplocytheridea 

Stephenson in shape and general hinge features, but 

the hinge surface is not crenulate, and there is an anterodorsal sulcus that defines the eye tubercle. Like 

Apatocythere some species of Haplocytheridea bear the 

accommodation groove above the hinge surface in the 

left valve. In the muscle scar of Haplocytheridea there 

are two spots anterad to the main group, but only one in 

Apathocythere. Schuleridea Swartz and Swain (1946) 

is closely similar to Apatocythere but the terminal 

hinge teeth and sockets are crenulate in S. acwminata 

Swartz and Swain, the genotype. The interterminal 

portion of the left valve hinge of S. acuminata consists 

of a bar rather than a groove, and the interterminal area 

of the right valve hinge consists of the simple valve 

e'dge that either is opposed to the corresponding edge 

of the left valve or slightly overlaps it. The presence 

of the accommodation groove above the hinge in the left 

valve of Schuleridea suggests that the left does not 

overlap the right along the hinge, but the exact relationships are not clear.

Schuleridea umbonata Swartz and Swain lacks observable crenulation of the terminal teeth, and perhaps 

should be placed in Apatocythere but the interterminal 

area of the left valve consists of a bar rather than a 

groove, and in the right the midportion of the hinge 

apparently slightly overlaps the edge of the left.

Apatocythere? lanceolata Swain, n. sp. 

Plate 9, figures 39, 41, 42, 46

Shell subovoid-acuminate in lateral view; greatest 

height about median, dorsal margin moderately convex; 

ventral margin slightly convex, somewhat sinuous in
MESOZOIC OSTRACODA 73

right valve; anterior margin broadly rounded, subtruncate above; posterior margin narrowly rounded, most 

extended a little below midheight. Left valve larger 

than right, extending beyond the other around entire 

periphery, forming a small mnbo in mid-dorsal region. 

Valves moderately convex; greatest thickness median.

Surface of valves finely punctate. A shallow, oblique, anterodorsal sulcus defines a small superjacent 

swelling that probably represents the eye tubercle. Anterior sixths of valves compressed to form a curving 

marginal zone.

Internal features not observed.

Length of holotype (pi. 9, fig. 39) 0.83 mm, height 

0.50 mm, thickness 0.37 mm.

Relationships: In its general outline, umbonate left 

valve, eye tubercle, and anterodorsal oblique sulcus this 

species is related both to Apatocythere Triebel and to 

Schuleridea Swartz and Swain. Differences in hingement serve to distinguish these genera but the hinge 

features of A A lanceolata are not known. A more 

strongly arched dorsum makes Schuleridea typically 

more triangular in outline than \Apatocy'there. The 

elongate shell, together with the other features noted 

above indicate that the new species belongs in the genus 

Apatocythere.

The type of the genus, Apatocythere simulans Triebel, 

(1940, p. 170) from the upper Hauterivian and lower 

Barremian of Europe is somewhat less elongate, has a 

smaller left valve umbo and bears anteromarginal 

spines, but otherwise is close to the new species.

Occurrence: In the Hatteras Light Well No. 1 the 

species was obtained from 6,930-6,940 feet, beds of 

Trinity (?) and pre-Trinity (?) age undifferentiated, 

U.S.N.M. 106974.

Apatocythere? leguminoidea Swain, n. sp. 

Plate 9, figures 40, 43, 45

Shell subelliptical in lateral view; greatest height 

anterad of midlength; hinge margin gently convex 

with rounded, very obtuse but distinct cardinal angles; 

ventral margin slightly convex in left valve, nearly 

straight to slightly sinuous in right; anterior margin 

broadly rounded, truncate above midheight; posterior 

margin more narrowly but also more uniformly 

rounded. Left valve larger than right and extending 

beyond the other except in truncated dorsal portion of 

anterior margin more narrowly but also more uniformly rounded. Convexity moderate, greatest thickness slightly posteromedian.

Anterior and postventral marginal portions of 

valves compressed to form a flattened border. Elongated eye tubercle at anterodorsal margin bend, subjoined by a shallow oblique sulcus. Surface of single 

specimen at hand poorly preserved, but fine pitting can 

be observed in dorsal half of right valve and ventral 

portion of left valve. Internal features unknown.

Length of holotype 0.93 mm, height 0.55 mm, thickness 0.35 mm.

Relationships: This species is less pointed posteriorly 

than A.? lanceolata, n. sp., and is more elongate and 

lacks the ventral swelling of A.? tumidosa, n. sp., but 

like those two species has the anterior end compressed 

and bears a well-defined anterodorsal oblique sulcus and 

eye tubercle. Apatocythere ellipsoidea Triebel from 

the Lower Cretaceous of Germany is similar to J..? 

leguminoidea in general shape but is slightly more 

pointed posteriorly and the anterodorsal eye tubercle 

and sulcus are not so strongly developed.

Occurrence: The holotype is from the Hatteras Light 

well No. 1, 6,350-6,360 feet, beds of Trinity (?) and preTrinity (?) age undifferentiated, U.S.N.M. 106976. 

In the North Carolina Esso well No. 2 a specimen was 

obtained from 5,560-5,570 feet in the undifferentiated 

beds of Trinity (?) and pre-Trinity (?) age, U.S.N.M. 

106975.

Apatocythere? tumidosa Swain, n. sp.

Plate 9, figure 44

Shell subovoid in lateral view; greatest height about 

median; dorsal margin moderately arched, hinge portion nearly straight and slightly more than half of 

shell length; ventral margin gently convex, that of 

right valve slightly sinuous; anterior margin broadly 

rounded, subtruncate above; posterior margin slightly 

narrower but more uniformly rounded. Left valve 

larger than right, strongly umbonate along hinge, and 

otherwise extending strongly beyond right along dorsal 

slopes and midventrally.

Convexity of possible male dimorphs moderate, that 

of possible females strong; greatest convexity in ventral half of shell where surface of females is more or 

less tumid and produces a slight midventral overhang.

Anterior border of shell compressed to form a flattened shelf on each valve. Anterodorsally in right 

valve and parallel to margin is a low, short ridge that 

bears eye tubercle at its anterior end; subjacent to ridge 

is a shallow oblique sulcus. Corresponding ridge in 

left valve is shorter. Entire surface ornamented ,by 

small pits averaging about 0.03 nun in diameter, separated by interspaces of about equal width.

Muscle scar lies just anterad of midlength and consists of a vertical row of 3 or 4 spots with an additional 

more anterior spot. Hingement and other internal 

features not observed.

Length of holotype 0.77 mm, height 0.53 mm, thickness 0.37 mm.

Relationships: In general shape, compressed anterior 

end, and anterodorsal eye tubercle and sulcus this 

species is close to A.? leguminoidea, n. sp. which, however, lacks the swollen ventral surface, and the umbonation of the left valve is less pronounced.

Occurrence: The holotype is from the North Carolina 

Esso well No. 2, 8,300-8,310 feet, beds of Trinity (?)
74 OSTRACODA FROM WELLS IN NORTH CAROLINA

and pre-Trinity (?) age undifferentiated, U.S.N.M. 

106977. Other examples that probably represent the 

species were obtained from the Hatteras Light well No. 

1, 7,640-7,650 feet, 8,020-8,030 feet and 8,110-8,120 feet, 

all undifferentiated beds of Trinity (?) and preTrinity (?) age, and from the North Carolina Esso 

well No. 2, 5,520-5,530 feet, Trinity (?) group and preTrinity (?), undifferentiated.

Genus SCHULEKIDEA Swartz and Swain, 1946

Schuleridea hatterasensis Swain, n. sp.

Plate 1?, figures 35-38

IGytheridea (Haplocytheridea) aff. G. (H.) thorenensis Triebel, 

1938, Senckenbergiana, vol. 20, No. 6, p. 483, pi. 2, figs. 

30-34.

Shell subovoid in side view; greatest height about 

median; hinge margin slightly convex, a little more 

than half of shell length, with broadly obtuse cardinal 

angles; ventral margin gently convex, anterior margin 

.broadly and nearly uniformly rounded, slightly truncate above; posterior margin narrowly rounded, extended below. Left valve overlaps and extends beyond right around entire periphery; along hinge, left 

valve slightly umbonate, extending strongly beyond the 

right. Valves moderately convex; greatest thickness 

slightly posteromedian.

Anterior end of right valve strongly compressed, the 

surface rising steeply behind compressed area; anterior 

end of left valve less strongly compressed. A shallow 

oblique sulcus lies venterad of anterocardinal angle and 

of rounded eye tubercle. Posteroventral marginal areas 

of each valve compressed. Entire surface of valves 

ornamented with pits of varied size and spacing; those 

in central portion widely spaced.

Hinge of left valve consists of an anterior elongate 

socket with 5 or 6 denticles, an interterminal thick apparently noncrenulate bar and a posterior elongate 

crenulate socket; dorsad of bar is a wide groove (accommodation groove, "Ausweichfurche") that is externally 

visible in complete shells; it apparently is unoccupied 

except when valves are open (see Sylvester-Bradley, 

1948, p. 793; Triebel, 1940, p. 213, fig. 103). Hinge of 

right valve observed in a single, possibly immature, 

specimen; it consists of simple edge of valve bearing 

terminal, weakly crenulate, low, elongate, toothlike elevations; the interterminal hinge-edge of right valve 

probably overlaps interterminal bar of left valve, but 

the relationship is not clear.

Muscle scar not clearly observed but seems to consist mainly of a median subvertical row of 3 or 4 spots. 

Inner lamellae of moderate width, broadest anteriorly; 

line of concrescence and inner margin coinciding.

Length of holotype 0.72 mm, height 0.50 mm, thickness 0.35 mm.

Relationships: In general outline, straight hinge,

umbonate left valve, and anterodorsal short sulcus, this 

species conforms to characteristics prescribed for 

/Schwleridea Swartz and Swain (1946, p. 363). The 

hinge in that genus was described as consisting of terminal elongate teeth and sockets, crenulate in S. 

acvminata Swartz and Swain, the type species, but not 

crenulate in S. wribonata Swartz and Swain. $. umbonata and /S. pentagonalis Swartz and Swain possibly 

should be excluded from Schuleridea; they are close to 

Apatocy there Triebel (1940, p. 169) but differ slightly 

from that genus in the nature of the interterminal portion of the hinge.

The hinge of the left valve of Schuleridea hatterasensis, like that of Clithrocytheridea Stephenson, consists 

of terminal crenulate sockets separated by a bar. 

Clithrocytheridea, however, lacks the anterodorsal sulcus, the umbonation of the left valve, and at least in 

typical members of the genus has crenulations along the 

interterminal portion of the hinge. S. hatterasensis 

differs from other described species in having the anterior end strongly compressed, but otherwise is close 

to S. acuminata Swartz and Swain from the Upper 

Jurassic of the Gulf region.

Gytheridea (Haplocytheridea} thorenensis Triebel 

from the Valanginian of Germany is closely similar to 

the new species but apparently is not compressed anteriorly. C. (H.) sp. aff. G. (H.) thorenensis Triebel 

(1938, p. 483, pi. 2, figs. 30-34) appears to be compressed anteriorly and may be identical to S. hatteras 

ensis.

Occurrence: The holotype is from the Hatteras Light 

well No. 1, 6,477-6,482 feet, U.S.N.M. 106967; other 

specimens were obtained from the same well at a depth 

of 6,300-6,310 feet as well as from deeper levels, all in 

undifferentiated beds of Trinity (?) and pre-Trinity (?) age, TJ.S.N.M. 106968-106970. In the North 

Carolina Esso No. 2 well the species was obtained from 

5,330-5,340 feet and deeper, in undifferentiated beds of 

Trinity (?) and pre-Trinity (?) age.

Schuleridea? lactistris Swain, n. sp. 

Plate 9, figure 48

Shell subovate-triangular in lateral view; highest 

medially; dorsal margin strongly convex, gently and 

obtusely angulate at, and slightly truncate on either 

flank of, position of greatest height; ventral margin 

gently convex; anterior margin broadly rounded; posterior margin narrow, slightly extended medially, 

truncate above. Left valve larger than right, extending strongly beyond the other mid-dorsally and along 

ventrum, less strongly elsewhere. Valves moderately 

convex, greatest thickness slightly behind middle.

Surface of each valve bears prominent, broad low 

ridges parallel to terminal margins; at anterior end, a 

furrow lies between valve margin and ridge; dorsad
MESOZOIC OSTRACODA 75

of midheight each ridge bears a rounded low node; behind dorsal half of anterior ridge is an oblique shallow 

sulcus; a small low node lies just behind sulcus near 

its ventral termination. General surface of valves 

finely punctate. Internal features not observed.

Length of holotype and only known example 0.61 

mm, height 0.42 mm, thickness 0.30 mm.

Relationships: This species is very close to S. hatterasensis, n. sp. in outline, overlap, anterior marginal 

furrow, and anterodorsal sulcus. It differs from S. hatterasensis in possessing prominent, nodose, terminal 

marginal ridges. Strong ridges and nodes are a characteristic feature of several groups of nonmarihe ostracodes, including species of Metacypris, CyprideaIlyocypris, and Cytherissa. The present example suggests a fresh- or brackish-water environment for the 

containing sediments. S. hatterasensis may represent 

its marine morphological equivalent.

Occurrence: N. C. Esso No. 2 well, 4,970-4,980 feet, 

beds of Trinity (?) and pre-Trinity (?) age undifferentiated, U.S.N.M. 106979.

Schuleridea cf. S. pentagonalis, Swartz and Swain 

Plate 9, figure 49

Schuleridea pentagonalis, Swartz and Swain, 1946, Jour. Paleontology, vol. 20, p. 368, pi. 53, figs. 1-8.

Shell subovoid in lateral view; highest medially; 

dorsal margin strongly convex; ventral margin gently 

convex; anterior broadly rounded, extended below, 

posterior margin more narrowly rounded, strongly extended below. Left valve larger than right and completely extending beyond it; greatest extension in 

umbonate dorsum and midventrally. Convexity of 

valves moderate, greatest thickness median.

Anterior end of right valve very slightly compressed 

to form a flattened border. Anterodorsally a low ridge 

parallels margin and probably contains eye spot; subjacent to ridge is a broad, shallow, oblique sulcus. Surface minutely and weakly punctate. Internal features 

not observable.

Length of figured specimen 0.80 mm, height 0.53 mm, 

thickness 0.44 mm.

Remarks: In shape, anterodorsal sulcus, and weakly 

pitted surface this form is much like Schuleridea pentagonalis Swartz and Swain and is here provisionally 

included in that species. The slight compression of the 

anterior end in the present form is atypical of S. pentagonalis. Lack of knowledge of its internal features, 

and its rather poor preservation prevent certain classification.

Occurrence: Hatteras Light well No. 1, core 9,115- 

9,116 feet, Upper Jurassic (?) U.S.N.M. 106980. 

S. pentagonals occurs in the Schuler formation, Upper 

Jurassic of the central Gulf region (Swartz and Swain, 

1946, p. 368; Swain, 1949, p. 1,236).

Schuleridea cf. S. acuminata Swartz and Swain

Plate 9, figure 47

Schuleridea acuminata Swartz and Swain, 1946, Jour. Paleontology, vol. 20, p. 366, pi. 52, figs. 1-10, text figures 1 a-c.

Shell subtriangular in side view; greatest height 

slightly anterad of midlength; dorsal margin very 

strongly arched; ventral margin gently convex; anterior margin broadly rounded, most extended a 

little below midheight; posterior margin acuminate, 

strongly extended below. Left valve much larger than 

right, overlapping and extending beyond the other 

around entire periphery, greatest extension in umbonate 

middorsal region and midventrally. Valves moderately convex, greatest thickness median.

Terminal edges of right valve bear low ridgelike 

swellings; corresponding features not observed- on left 

valve. Anterodorsal low eye tubercle and subjacent 

shallow oblique sulcus clear in right valve, but are much 

less distinct on left. Surface of single specimen at hand 

poorly preserved, but part is ornamented with small, 

closely spaced pits. Internal features not observed.

Length 0.83 mm, height 0.56 mm, thickness 0.40 mm.

Remarks: This specimen is like 8. acuminata Swartz 

and Swain from the Schuler formation, Upper Jurassic 

of Arkansas in general shape, posterior marginal swelling on right valve, pitted surface, and anterodorsal sulcus, although the Schuler specimens do not have the 

dorsal margin of the left valve so strongly arched and 

lack the anteromarginal swelling on the right valve.

Occurrence: Hatteras Light well No. 1, 9,100-9,110 

feet, beds of Schuler (?) age. U.S.N.M 106978 8. acuminata occurs in the Schuler formation, Upper Jurassic 

of Louisiana and Texas (Swartz and Swain, 1946, p. 

366; Swain, 1949, p. 1,236).

Genus ASCIOCYTHERE Swain, n. gen.

Shell subovate in lateral view; highest near middle; 

dorsal margin moderately convex; ventral margin 

gently convex; ends rounded. Left valve typically 

larger than right. Convexity of valves moderate; 

surface smooth or pitted. .

Hinge of right valve consists of terminal crenulate, 

elongate teeth; the intervening valve edge faintly 

grooved for reception of opposing left valve bar. 

Hinge of left valve consists of terminal crenulate, elongate sockets, separated by a smooth or denticulate bar, 

dorsad of which is a well-defined accommodation 

groove. Inner lamellae narrow; line of concrescence 

and inner margin nearly coincide. Numerous simple 

radial canals occur around entire free margin. Muscle 

scar consists of an anteromedian vertical row of four 

spots, together with two additional more anterior spots.

Type species: Bythocypris rotundus Vanderpool.

Geologic range: Upper Jurassic?, Lower Cretaceous, 

and Upper Cretaceous(?).
76 OSTRACODA FROM WELLS IN NORTH CAROLINA

Relationships: The hinge of this genus differs from 

that in Clithvcytheridea Stephenson (1936) in lacking 

a well defined crenulated groove in the right valve, 

and in possessing a broader accommodation groove. 

Clithrocytheridea also has the dorsal slopes typically 

more truncated than in the present form. Haplocytheridea Stephenson (1936) has the posterior end more 

acuminate and the interterminal portions of its hinge 

are different. The Cretaceous representatives of 

B'aplo cytheridea possess some atypical hinge features 

that are in need of further study.

Asciocythere rotunda (Vanderpool) 

Plate 8, figures 22-33

Bythocypris rotundus Vanderpool, 1928, Jour. Paleontology, vol.

2, p. 102, pi. 13, figs. 5, 6. 

f Cytheridea amygdaloides brevis (Cornuel), Alexander, 1929,

Texas Univ. Bull. 2907, p. 70, pi. 4, fig. 13. 

f Cytheridea rotundus Vanderpool, 1933, Jour. Paleontology,

1933, vol. 7, p. 411.

Shell subovate in lateral view; greatest height about 

median; dorsal margin strongly and nearly uniformly 

convex; ventral margin slightly convex in left valve, 

nearly straight to slightly sinuous in right valve; anterior margin broadly rounded, truncate in dorsal half; 

most extended medially, posterior margin more narrowly rounded, slightly truncate above, most extended 

a little ventrad of midheight. Left valve much larger 

than right, extending strongly beyond the other dorsally and ventrally, less strongly terminally. Valves 

rather strongly convex, greatest thickness median. 

Surface bears faint, widely separated small pits, otherwise smooth. Right valve in well preserved specimens 

bears a very weak groove parallel to anterior margin, 

and a faint ridge along ventral portion of posterior 

margin; corresponding features not observed on left 

valve.

Hinge of left valve consists of an anterior, elongate, 

shallow, rather coarsely but weakly denticulate socket, 

uii interterminal, high, apparently nondenticulate bar, 

and a posterior elongate, shallow, weakly denticulate 

socket; dorsad of median bar is a broad accommodation 

groove for reception of mid-portion of dorsal margin 

of right valve; complete hinge 0.7 and interterminal 

bar 0.5 of shell length, respectively. Hinge of right 

valve not clearly observed. Inner lamellae narrow, 

steeply inclined inward; line of concrescence and inner 

margin coincide. Muscle scar not observed.

Length of a figured specimen (pi. 8, fig. 22) 0.67 mm, 

height 0.44 mm, thickness 0.35 mm.

Relationships: The present species is closely similar 

in outline and convexity to several species of Cytheridea, 

including C, reniformis van Veen, C. limburgensis 

van Veen and C. fortior van Veen from the late 

Upper Cretaceous Maestrichian stage of the Netherlands (van Veen, 1934). The writer does not know 

whether the hingement of the Netherlands forms is more

closely allied to Cytheridea or to Asciocythere. The 

form identified as Cytheridea (Haplocytherideaf] 

amygdaloides brevis (Cornuel) by Alexander (1929) 

and Schmidt (1948) is, among American species, very 

close to Asciocythere rotunda. The example figured 

by Alexander from the Kiamichi formation and upper 

part of Goodland limestone of Texas is slightly more 

convex ventrally and has the ventral overlap more 

closely restricted to the midportion of the shell, but 

otherwise seems to be the same as the present species. 

The writer is not acquainted with the hinge of the 

species from Texas, but external characteristics suggest 

that it may be considered conspecific with A. rotunda.

The examples described and figured as Haplocytherideaf amygdaloides brevis (Cornuel),by Schmidt (1948, 

p. 426, pi. 62, figs. 20-22) have the interterminal portion 

of the hinge crenulate rather than unomamented as in 

the present species, have broader and flatter inner 

lamellae, and are more strongly pitted.

Many years ago Cythere amygdaloides brevis Cornuel 

was placed in synonymy with Cytherella ovata 

(Roemer) (Jones, 1849, p. 28; Jones and Hinde, 1890, 

p. 45).

Occurrence: Hatteras Light well No. 1, 6,300-6,310 

feet, and.below, beds of Trinity (?) and pre-Trinity 

(?) age, undifferentiated, U.S.N.M. 106923-106931.

Asciocythere? cf. A.? amygdaloides (Cornuel) 

Plate 8, figures 37-39

Cythere amygdaloides Cornuel, 1846, Soc. Geol. France, Mem.

ser. 2, vol. 1, p. 197, pi. 7, figs. 1-9. 

Cytheridea amygdaloides (Cornuel), Alexander, 1929, Texas

Univ. Bull. 2907, p. 69, pi. 4, figs. 16, 17.

Shell elongate-subreniform in lateral view; greatest 

height slightly anterad of middle; dorsal margin moderately convex, anterior slope steeper; ventral margin 

slightly sinuous; anterior margin broadly rounded; 

posterior margin slightly more narrowly rounded. Left 

valve larger than right, and extending more or less uniformly beyond the other around entire periphery. 

Valves moderately convex, greatest thickness median.

Terminal margins of right valve bear narrow low 

rims; surface bears scattered large very weak pits.

Hinge of left valve consists of an anterior elongate 

socket bearing 5 or 6 transverse denticles, an interterminal high non-denticulate bar, dorsad of which is a 

conspicuous accommodation groove, and a posterior 

elongated socket; in two separated left valves at hand, 

posterior socket filled with matrix which obscures possible denticulations. Hinge of right valve observed in 

only one abraded specimen; it bears a faint groove along 

hinge margin but does not have other hinge features 

preserved. Inner lamellae narrow, sloping steeply toward interior of valve; line of concrescence and inner 

margin apparently coincide. Muscle scar consists of an 

anteromedian vertical row of four spots, together with 

a single, more anterior spot.
MESOZOIC OSTRACODA 77

Length of a figured specimen (pi. 8, fig. 38) 0.83 mm, 

height 0.46 mm, thickness 0.34 mm.

Remarks: This species conforms to characteristics 

prescribed for Asciocythere in shape, ornamentation 

and hingement. The present specimens are similar 

in external appearance to Cytheridea amygdaloides 

(Cornuel) as figured and described by Alexander 

(1929) from the Kiamichi formation of Texas, but 

there is uncertainty about the generic status of both 

Alexander's and Cornuel's specimens. Cornuel's original figures show no denticulation of the terminal teeth 

and sockets nor does he mention it in his description, so 

the species may be more closely related to Apatovythere than to Asciocythere.

As compared to Asciocythere rotunda (Vanderpool) 

the present specimens are more elongate and lack the 

strong dorsal and ventral left valve overlap of that 

species. Otherwise the two are so similar that it may 

prove desirable to consider them as dimorphs of a single species.

Occurrence: Hatter as Light well No. 1, core sample 

6,132-6,137 feet and in several drill-cutting samples below that level down to 6,760-6,770 feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, 

U.S.N.M. 106935-106937.

Asciocythere? triangularis Swain, n. sp. 

Plate 8, figure 34

Shell subtriangular in lateral view; greatest height 

slightly behind middle of shell; dorsal margin strongly 

convex; ventral margin moderately convex; anterior 

margin broadly rounded, somewhat extended below; 

posterior margin more broadly rounded, extended below. Left valve larger than right, extending strongly 

beyond the other dorsally and ventrally, less strongly 

at ends. Valves moderately convex; thickest slightly 

behind center. Surface of holotype poorly preserved, 

but seems to have lacked ornamentation.

Internal features not observable because shell is filled 

with recrystallized matrix.

Length of holotype 0.58 mm, height 0.43 mm, thickness 0.37 mm.

Relationships: In general shape,, overlap, and lack 

of anterodorsal eye node and sulcus this species conforms to Asciocythere, but lack of knowledge as to its 

internal characteristics prevents definite classification. 

There is also uncertainty as to the orientation of the 

form. As it is here oriented the greatest height and 

more broadly rounded end are posterior in position 

whereas in typical Asciocythere the reverse is true. 

Alexander and Alexander (1933) observed reversal of 

valve size and hingement in a species of Cytheridea, 

and it is possible the present form may also be an 

example of such reversal. The strongly arched dorsum 

of the larger valve precludes assignment to Gytherella 

Jones. Cytheridea ovata Bosquet, as figured by van

Veen (1935) is like the present species in the posterior 

position of the greatest height and the broader rounding of the posterior end and, although Asciocythere 

triangularis is somewhat shorter and higher, may prove 

to be conspecific with the species figured by van Veen 

and with the example herein assigned to A. macropunctata.

Occurrence: Hatteras Light well No. 1, 6,430-6,440 

feet, beds of Trinity (?) and pre-Trinity (?) age, 

undifferentiated, U.S.N.M. 106932.

Asciocythere macropunctata Swain, n. sp. 

Plate 8, figure 21

fCytheridea ovata Bosquet. Van Veen, 1935, Natuurhist. 

Maandblad, Jaargang 24, No. 9, p. 106, pi. 3, figs. 1-24.

Shell subovate in lateral view; greatest height 

slightly behind center of shell; dorsal margin moderately convex; anterior slope slightly flattened; ventral 

margin gently convex; anterior margin rounded, 

slightly extended below midheight; posterior margin 

more broadly rounded, slightly angulate and extended 

at midheight. Left valve larger than right, overlapping and extending strongly beyond the other around 

entire periphery. Valves moderately convex, greatest 

thickness slightly posterior to middle. Surface bears 

widely separated rather large pits; interspaces equalling two to four times width of pits.

Hinge not clearly seen, but in left valve it consists 

of terminal sockets, both of which apparently are crenulate, and an interterminal bar that is not visibly crenulate; dorsad of bar is a narrow accommodation groove. 

Other internal features not observed.

Length of holotype 0.58 mm, height 0.36 mm, thickness 0.27 mm.

Relationships: The hingement (although incompletely known), the general outline, and overlap relationships of this species ally it with Asciocythere. As 

compared to A. rotunda (Vanderpool), it is more 

coarsely pitted and the greatest height is postmedian 

rather than median. Cytheridea ovata Bosquet as figured by van Veen (1935) is very close to the present 

example and the two may be conspecific. Lack of 

knowledge of the hinge of the species from the Netherlands prevents a definite comparison.

Occurrence: Hatteras Light well No. 1, core 3,693- 

3,703 feet, beds of Eutaw(?) age, U.S.N.M. 106933.

Asciocythere? acuminata Swain, n. sp. 

Plate 8, figure 20

Shell elongate subovate in lateral view; highest 

medially; dorsal margin moderately arched, slightly 

truncated before and behind point of greatest height 

and along posterior slope; ventral margin of left valve 

gently convex, of right valve nearly straight; anterior 

margin rather broadly rounded, slightly extended below; posterior margin narrowly rounded extended
78 OSTRACODA FROM WELLS IN NORTH CAROLINA

below. Left valve much larger than right, overlapping 

and extending beyond the other around entire periphery. Valves strongly convex, greatest thickness 

slightly postmedian.

Posterior termination of left valve thickened to form 

a slight protuberance at position of greatest length; 

posterior end of right valve bears a similar small protuberance that lies slightly ventrad of corresponding 

feature on left valve. Ventral third of right valve 

slopes steeply toward margin. Narrow marginal border of left valve slopes rather sharply to the contact 

with right valve. Surface smooth except for a few 

widely spaced small shallow pits.

Hinge not observed in the single specimen at hand. 

Muscle scar as viewed by reflected light is seen to consist of a subvertical row of four spots near middle of 

shell, together with two more anterior spots.

Length of holotype 0.71 mm, height 0.40 mm, thickness 0.35 mm.

Relationships: In outline, convexity, strong left valve 

overlap and generally smooth surface this form is close 

to Asciocytheref cf. Af amygdaloides (Cornuel) of this 

paper, but incomplete knowledge of the internal features precludes definite classification of both species. 

A.f acuminata is somewhat more pointed posteriorly 

and lacks the terminal low marginal rims found in 

the right valve of A.f amygdaloides. Oytheridea ovata 

Bosquet as figured by van Veen (1935, pi. 3, figs. 1-25) 

is similar in overlap and convexity, and general outline but has the greatest height markedly posterior in 

position.

Occurrence: Hatteras Light well No. 1, 3,780-3,790 

feet, beds of Eutaw (?) age, U.S.N.M. 106922.

Asciocythere? leguminoides Swain, n. sp. 

Plate 8, figure 36

Cytheridea sp. Swain, 1949, Am. Assoc. Petroleum Geologists 

Bull., vol. 33, p. 1,236, pi. 33, figs. 9, 10.

Shell subovate in lateral view; highest medially; 

dorsal margin moderately convex; ventral margin of 

right valve nearly straight, of left valve slightly convex; anterior margin uniformly rounded; posterior 

margin, somewhat extended a little ventrad of midheight, truncate above. Left valve larger than right, 

extending beyond the other around entire periphery. 

Valves strongly convex, with greatest thickness slightly 

posterior to midlength. Surface smooth. Internal 

features not observed.

Length of holotype 0.64 mm, height 0.40 mm, thickness 0.35 mm.

Relationships: In general outline and strong convexity this species is related to Asciocythere, but lack 

of knowledge of its internal characters precludes definite classification. An apparently identical form occurs 

in the Dorcheat member of the Schuler formation of 

Louisiana (Swain, 1949, p. 1,236, pi. 3, figs. 9, 10).

Occurrence: Hatteras Light well No. 1, 9,030-9,040 

feet, beds of Schuler (?) age, U.S.N.M. 106934.

Genus HAPLOCYTHERIDEA Stephenson, 1936

Haplocytheridea? graysonensis (Alexander)

Plate 8, figures 16, 17

Cytheridea graysonensis Alexander, 1929, Texas Univ. Bull. 

2907, p. 72, pi. 5, figs. 3, 4.

Shell subovate-acuminate in lateral view; greatest 

height approximately median; dorsal margin moderately convex; ventral margin nearly straight, slightly 

sinuous, with slight concavity in posterior half; anterior 

margin broadly rounded; posterior margin narrowly 

rounded, extended below. Left valve larger than right, 

extending beyond the other rather strongly except 

posteriorly. Convexity of valves moderate with greatest thickness median to slightly posteromedian. Surface smooth.

A separated pair of valves is available for study in 

the present material, but neither shell clearly reveals 

the internal features. In the left valve the hinge seems 

to have terminal crenulate sockets, but the area between 

them is poorly preserved; there is, however, a welldefined accommodation groove dorsad of the interterminal area. In the right valve, terminal elongate 

toothlike elevations separated by a bar formed of valve 

edge are preserved. Other internal features not 

observable.

Length of a figured specimen (pi. 8, fig. 17) 0.70 mm, 

height 0.40 mm, thickness 0.24 mm.

Remarks: The observed hinge features, the shell outline, and the overlap relationships ally the present 

species with Haplocytheridea Stephenson and it is 

tentatively placed in that genus.

Occurrence: Hatteras Light well No. 1, core 4,485- 

4,495 feet, beds of Eagle Ford(?) age (U.S.N.M. 

106919) and in samples as deep as 7,310-7,320 feet, in 

the undifferentiated beds of Trinity (?) and preTrinity (?) age. Alexander (1929, p. 72) recorded it 

in the upper part of the Washita group and lower part 

of the Woodbine formation in northern Texas, and 

found it to be most abundant in the Grayson formation.

Haplocytheridea? berryi Swain, n. sp. 

Plate 8, figure 18

Shell elongate-subovate in lateral view; highest approximately two-fifths from anterior end; dorsal margin moderately convex; ventral margin nearly straight; 

anterior margin broadly rounded; posterior margin 

very narrowly rounded, strongly extended below. Left 

valve larger than right, overlapping and extending beyond the other conspicuously except at position of 

greatest height along dorsum where the overlap is much 

less. Convexity of valves moderate, greatest thickness 

median or slightly anteromedian.
MESOZOIC OSTRACODA 79

Surface ornamented by closely but somewhat irregularly spaced shallow pits. Anterior end compressed to 

form a narrow shelf paralleling margin of each valve. 

Posterior narrowly rounded termination of right valve, 

thickened to form slight protuberance.

Hingement not observed. Muscle scar not clearly 

visible but the main element is a vertical anteromedian 

row of four spots.

Length of holotype 0.73 mm, height 0.39 mm, thickness 0.30 mm.

Relationships: In general shape, compressed anterior 

marginal zone and slight posterior protuberance on the 

right valve, this species is close to H. monmouthensis 

(Berry). H.? berryi is more densely pitted and somewhat longer in proportion to height than H. monmouthensis.

Occurrence: Hatteras Light well No. 1, core 3,380- 

3,390 feet, Black Creek formation, U.S.N.M. 106920.

Haplocytheridea monmouthensis (Berry) 

Plate 8, figure 19

Cytheridea monmouthensis Berry, 1925, Am. Jour. ScL, 5th ser.,

vol. 9, p. 486, fig. 10. Alexander, 1929, Texas Univ.

Bull. 2907, p. 74, pi. 5, figs. 11-14. 

Cytheridea (Haplocytheridea) monmouthensis Berry. Swain,

1948, Maryland Dept. Geol. Mines, and Water Res., Bull.

2, p. 212, pi. 14, fig. 14.

Shell subtriangular in lateral view; highest about 

two-fifths from anterior end, dorsal margin strongly 

convex, truncate on either side of point of greatest 

height; ventral margin gently convex in left valve, 

nearly straight in right valve; anterior margin broadly 

rounded, slightly extended medially; posterior margin 

acuminately rounded, strongly extended ventrally. 

Left valve larger than right, extending strongly beyond the other except in anterior and posterior portions 

of ventrum. Valves strongly convex, greatest thickness median.

Surface bears scattered pits; right valve bears three 

medial subvertical furrows lined with pits; corresponding furrows much weaker or absent in left valve. Posterior acuminate termination of both valves bear small 

protuberances; one on right valve slightly more ventral 

in position.

Internal features of present specimens not observed.

Length of figured specimen 0.75 mm, height 0.45 mm, 

thickness 0.36 mm.

Remarks: In shape, sparsely pitted surface, median 

vertical pitted grooves, and posteroventral flangelike 

expansions the present specimens resemble Haplocytheridea monmouthensis (Berry).

The internal features of the species have been observed in specimens from the Blufftown formation at 

Union Springs, Ala. The right valve hinge consists 

of terminal, elongate, crenulate teeth, an interterminal 

low, narrow bar of which the dorsal flank is crenulate,

and a narrow groove lying dorsad of the bar and teeth. 

The hinge of the left valve consists of terminal elongate crenulate sockets passing into an interterminal 

narrow crenulate groove, dorsad of groove, and separated from it by a narrowed ridgelike extension of the 

valve edge is a weak accommodation groove. The 

muscle scar consists of an anteromedial vertical row of 

four spots, together with two slightly more anterior 

spots. Inner lamellae of moderate width anteriorly 

and ventrally, narrow posteriorly; line of concrescence 

and inner margin separate. Radial canals numerous 

and closely spaced anteriorly, few and widely spaced 

ventrally and posteriorly.

Occurrence: North Carolina Esso well No. 2, 2,750- 

2,760 feet, Black Creek formation, U.S.N.M. 106921. 

The species occurs also in the Monmouth formation of 

Maryland (Berry, 1925, Swain, 1948) in the upper twothirds of the Navarro group of northern Texas (Alexander, 1929, p. 75) and in the Blufftown, Demopolis, 

•Ripley, Prairie Bluff, and Providence formations of 

Alabama.

In examples of this species from the Blufftown formation of Alabama are numerous instances of reversal 

of overlap and hingement. Alexander and Alexander 

(1933) have pointed out other instances of reversal in 

Cretaceous Cytheridea.

Haplocytheridea? sp. aff. H.? plummeri (Alexander) 

Plate 8, figure 15

Shell elongate-subtriangular in side view; highest 

about two-fifths from anterior end; dorsal margin moderately convex, obtusely angulated at point of greatest 

height; ventral margin of left valve slightly convex, of 

right valve nearly straight to slightly sinuous; anterior 

margin broadly rounded; posterior margin acuminate, 

strongly extended below, subtruncate above. Left 

valve larger than right, extending strongly beyond the 

other along ventrum, somewhat less strongly elsewhere. Valves moderately convex, greatest thickness 

slightly anteromedian.

Surface sparsely set with small pits; medially, pits 

arranged in two or three crude subvertical short rows. 

Anterior end of right valve bears a weak furrow parallel to margin. At posterior acumination of right valve 

in some examples shell thickened to form a small protuberance.

Internal features of present specimens not observed.

Length of figured specimen 0.68 mm, height 0.40 mm, 

thickness 0.28 mm.

Remarks: The present examples are close to Cytheridea plummeri Alexander (1929, p. 73) in shape and 

sparsely pitted surface but differs in possessing a anterior marginal furrow on the right valve and in lacking 

the median vertical pitted grooves commonly found in 

C'. plummeri.

The hinge in Alexander's Texas examples of Cyther-
80 OSTRACODA FROM WELLS IN NORTH CAROLINA

idea plwnmeri is unknown but specimens from the 

Middle Atlantic region ascribed to the species by 

Schmidt (1948, p. 425) have the left valve hinge composed of terminal sockets and an intervening bar. 

Although in other respects the species is like Haplocytheridea Stephenson, the left valve hinge of that 

genus bears an interterminal groove rather than a bar, 

hence the tentative assignment of O. plwnmeri to 

Haplocytheridea.

Occurrence: Hatteras Light well No. 1, 3,550-3,560 

feet, Black Creek (?) formation and below. The figured specimen (pi. 8, fig. 15) is from a drill-cutting 

sample, 3,990-4,000 feet in beds of Eutaw(?) age, 

U.S.N.M. 106918.

Genns BBACHYCYTHEBE Alexander, 1933

Brachycythere dareusis Swain, n. sp.

Plate 8, figures 40, 41

Shell rather large and thick-walled, subovate in 

lateral view; greatest height about two-fifths from anterior end; dorsal margin moderately convex; ventral 

margin slightly less convex; anterior margin broadly 

rounded and most extended a little ventrad of midheight, subtruncate above, medial and ventral portions 

of each valve weakly crenulate; posterior margin narrowly rounded, extended ventrad of midheight. Left 

valve larger than right, extending beyond the other 

except midventrally; most pronounced extension along 

dorsum. Valves strongly convex, greatest thickness in 

ventral third of shell and slightly back of middle.

Midportion of ventrum in each valve strongly inflated to form blunt alae that slightly overhang ventral 

margins; a broad but distinct and high ridge forms 

crest of each ala. Anterior end somewhat compressed; 

posterior and postventral area of each valve more 

strongly compressed. Each valve bears a low anterodorsal eye tubercle bordered ventrally by a weak, 

oblique furrow. General surface smooth and shiny.

Internal features not observed.

Length of holotype 1.04 mm, height (including alae) 

0.72 mm; thickness 0.61 mm.

Relationships: Like B. sphenoides (Reuss) (Alexander, 1933, p. 206) from the Upper Cretaceous, and 

B. hddleyi Stephenson (1946, p. 333) from the Eocene 

B. darensis bears a conspicuous ridge along the crest 

of each ala; it is much less pointed posteriorly than 

B. sphenoides, and has less ventral overhang of the alae 

beyond the margin of the shell than B. hadleyi. In 

general outline of the shell it is similar to B. ovata 

(Berry) (1925, p. 484) from the Upper Cretaceous but 

the latter lacks ridges surmounting the alae. A form 

identified as B. hadleyi Stephenson (Swain, 1951) from 

the Paleocene(?) in the North Carolina Esso No. 2 

well is very close to the present species and may be 

identical, but has a more narrowly rounded posterior

margin, in which the dorsal slope is more truncate, and 

a slightly more convex dorsum.

Occurrence: Hatteras Light well No. 1, 3,200-3,210 

feet, Black Creek(?) formation, U.S.N.M. 106938.

Brachycythere sphenoides (Eenss) 

Plate 8, figures 42, 43

Cythere sphenoides Reuss, 1854, Denkschr. K. Akad. Wissen.

Wien, vol. 7, p. 141, pi. 26, fig. 2. 

Alexander, 1929, Texas Univ. Bull. 2907, p. 81, pi. 7, figs.

9, 14. 

Cytheropteron sphenoides (Reuss), Jones and Hinde, 1889,

Suppl. Mono. Cret. Entom., England, Ireland, Palaeontographical Soc. London, p. 33, pi. 1, figs. 18-20. 

Cytheropteron sp. B., Israelsky, 1929, Arkansas Geol. Survey,

Bull. 2, p. 8, pi. 1A, figs. 2a-c. 

Brachycythere sphenoides (Reuss), Alexander 1933, Jour.

Paleontology, vol. 7, p. 205, pi. 25, figs. 3a-c, 14a, b, pi.

26, figs. 7a, b, pi. 27, fig. 19.

Shell subtriangular in lateral view; highest about 

two-fifths from anterior end; dorsal margin strongly 

arched, with posterior slope truncated and slightly concave, ventral margin gently convex; anterior margin 

broadly rounded; posterior margin acuminately 

rounded, strongly extended submedially. Left valve 

much larger than right, extending strongly beyond the 

other as a small umbo in mid-dorsal region.

Midportion of each valve strongly convex, with ventrum expanded to form short alae, crest of each ala 

surmounted by a broad rather high ridge parallel to 

margin; shell triangular in end view. Posterior end 

of shell strongly compressed; anterior end less strongly 

co.mpressed. Anterodorsally each valve bears a low 

eye tubercle subjoined by a short oblique sulcus. General surface of valves smooth except for scattered 

shallow pits. Internal features not observed.

Length of a figured specimen 0.91 mm, height 0.58 

mm, thickness 0.50 mm.

Remarks: The present examples are slightly less 

acuminate posteriorly, and most do not have preserved 

tiny terminal spines characterizing the forms identified 

as this species by Alexander (1929, p. 81, 1933, p. 206) 

from the Austin chalk and lower part of the Taylor 

marl of northern Texas; in other respects they are 

similar. B. taylorensis (Alexander) from the upper 

part of the Austin chalk and lower part of the Taylor 

marl is a nearly identical species but bears a punctate 

ridge at the crests of the alae and is more broadly 

rounded posteriorly.

Occurrence: Hatteras Light well No. 1, core, 3,500- 

3,510 feet, Black Creek (?) formation, U.S.N.M. 106939.

Brachycythere nansiformis Swain, n. sp. 

Plate 8, figures 44-47

Shell subtriangular to subovate-acuminate in lateral 

view; greatest height a little more than one-third from 

anterior end; dorsal margin strongly arched, long
MESOZOIC OSTRACODA 81

posterior slope truncated and slightly concave; ventral 

margin gently to moderately convex; anterior margin 

broadly rounded, bearing tiny denticulations on each 

valve in well preserved specimens; posterior margin 

acuminate, strongly extended medially, truncate and 

slightly concave above.

Left valve larger than right, extending very strongly 

beyond the other as a short umbo anteromid-dorsally, 

less strongly elsewhere. Median surface of valves 

strongly convex with ventrum swollen to produce short 

alate expansions, and projecting beyond ventral contact of valves; crest of each ala bears a low longitudinal 

ridge with a broad furrow about it; a second weak longitudinal ridge lies dorsad of furrow. A prominent 

elongate eye tubercle lies at anterodorsal angle; ventrad 

of tubercle in right valve is a short oblique sulcus, corresponding feature in left valve is deeper, wider and 

more pit-like. Anterior sixth of shell compressed, 

sharply defined with respect to median swollen portion, 

and in some specimens a narrow groove separates the 

two areas. Posterior end strongly compressed but 

passes gradually into median surface except at posteroventral terminations of alae where an abrupt change of 

slope occurs. General surface bears widely spaced deep 

pits.

Muscle scar consists of a slightly anteromedian, subvertical row of four or five spots and a single more 

anterior spot. Other internal features not seen.

Length of cotype (male dimorph, U.S.N.M. 106940) 

0.91 mm, height 0.56 mm, thickness 0.43 mm; length of 

cotype (female dimorph, U.S.N.M. 106941) 1.05 mm, 

height 0.57 mm, thickness 0.51 mm.

Relationships: Although the hinge of this species has 

not been seen, the general outline, overlap relationships, 

ventral alation, and musculature ally it with Brachythere. In comparison to B. sphenoides (Reuss) the 

new species is more strongly pitted, and has its greatest 

height more anterior in position. B. jersey"ensis Jennings (1936, p. 48) from the Navesink marl of New 

Jersey is a strongly pitted form, but the posterodorsal 

slope is not truncated and the posterior terminations of 

the alae are more strongly elevated. B. infundibuliformis van Veen (1935, p. 28) from the Cretaceous of 

Holland bears close resemblance to the present example 

in outline, but is more weakly alate, lacks the ventral 

longitudinal ridge and furrow and lacks the deep surface pits.

Occurrence: Hatteras Light well No. 1, 3,640-3,650 

(U.S.N.M. 106942) Black Creek(?) formation, and 

3,780-3,790 feet (U.S.N.M. 106940), beds of Eutaw( ?) 

age; North Carolina Esso well No. 2, 2,750-2,760 feet 

(U.S.N.M. 106941), beds of Eutaw(?) age or Black 

Creek(?) formation.

Brachycythere arachoides (Berry) 

Plate 9, figure 22

Cythere arachoides Berry, 1925, Am. Jour. Sci., 5th ser., vol. 9,

p. 484, fig. 5. 

Cythere rectanyulapora Berry, 1925, Am. Jour. Sci., 5th ser.,

vol. 9, p. 483, fig. 4. 

Brachycythere arachoides (Berry), Schmidt, 1948, Jour

Paleontology, vol. 22, p. 415, pi. 62, figs. 13-16.

Shell subpyrif orm in lateral view; highest about onethird from anterior end; dorsal margin sinuous, about 

three-fourths of shell length and with broadly obtuse 

cardinal angles; ventral margin gently convex, posteriorly converging strongly with dorsum; anterior margin broadly rounded, finely spinose in ventral twothirds; posterior margin bluntly acuminate, extended 

medially. Left valve larger than right, extending beyond the other along ventrum and at cardinal angles; 

posteriorly, right valve extends slightly beyond left.

Ends compressed; swollen midportion of each valve 

bears a broad ventral ridgelike longitudinal swelling, a 

median longitudinal ridge, and a dorsal longitudinal 

ridge that projects beyond edge of valve medially and 

is transected by an oblique furrow just behind anterocardinal angle. A large, rounded, median pit, bordered 

anteriorly by a narrow ridge, lies between middle and 

dorsal longitudinal ridges. General surface rather 

coarsely punctate. Internal features not observed.

Length of figured specimen 0.83 mm, height 0.52 mm, 

thickness 0.49 mm.

Remarks: The shape and surface ornamentation of 

this species ally it with Protocythere Triebel (1938, p. 

180) but the hingement in examples from other localities is closer to that of Brachycythere Alexander.

The hinge of a left valve from the Marlbrook marl 

(late Taylor age) of Arkansas, kindly loaned by C. I. 

Alexander, shows the following features: an anterior 

deep, rounded socket, postjacent high blunt tooth, long 

interterminal crenulate bar, formed of the thickened 

valve-edge, and a posterior elongate, shallow, crenulate 

socket. Opposing right valve hinge features are displayed on a specimen illustrated by Schmidt (1948, pi. 

62, fig. 13) from the Monmouth formation of Maryland 

and Delaware.

Occurrence: Esso Standard Oil Company North 

Carolina Esso well No. 2, 2,310-2,320 feet, Peedee(?) 

formation, (U.S.N.M. 106958).

Genus CYTHEBEIS Jones, 1849

Cythereis sp. aff. C. rugosissima Alexander

Plate 9, figure 5

Shell small, subquadrate in lateral view; highest 

about one-fifth from anterior end; dorsal margin nearly 

straight, cardinal areas of left valve slightly elevated; 

ventral margin gently convex, posteriorly converging 

with dorsum; anterior margin broadly rounded,
82 OSTRACODA FROM WELLS IN NORTH CAROLINA

slightly extended below, finely spinose around ventral 

marginal bend; posterior margin more narrowly 

rounded, with a notchlike concavity just ventrad of 

cardinal angle. Left valve larger than right, extending beyond the other along ventrum and at cardinal 

angles.

Anterior end of each valve bears a narrow moderately 

elevated marginal rim that lies closer to edge of valve 

ventrally than dorsally, and at anterior cardinal angle 

passes into a rounded eye tubercle; posterior end provided with a lower marginal rim. Posterior fourth of 

shell bears a strongly compressed area that marks termination of following longitudinal elements of ornamentation: a longitudinal ridge sending short spurs ventrally lies close to dorsal margin; a second high, narrow, 

longitudinal ridge occupies middle half of valve and 

has short spurs projecting from either flank. Along 

midportion of ventrum are two strongly elevated narrow ridges that merge anteroventrally; several spurs 

extend from the dorsal flank of the more dorsal of the 

two ridges; a short cross ridge connects their posterior 

terminations and two additional cross ridges lie anterior to micllength. General surface finely pitted. Internal features not observed.

Length of figured specimen 0.47 mm, height 0.29 mm, 

thickness 0.17 mm.

Remarks: This specimen probably represents an 

immature individual. It has less strongly elevated 

dorsal, ventral and anterior ridges, and a more strongly 

elevated median longitudinal ridge than O. rugosissima 

Alexander (1929, p. 101) from the Taylor formation of 

Texas but is similar to it in general outline and pattern of surface ornamentation. It may represent an 

immature molt of that species, but its relationships are 

not entirely clear. Cythereis elegans (Bosquet) from 

the Maestrichtian of Holland also is similar to the present form but the transverse short spurs from the longitudinal ridges are weaker and the ridges themselves 

are much broader. Comparisons with C. elegans were 

made on the basis of specimens kindly loaned by C. I. 

Alexander.

Occurrence: Hatteras Light well No. 1, 4,600-4,610 

feet, beds of Eagle Ford( ?) age, U.S.N.M. 106946.

Cythereis sp. aff. C. fredericksburgensis Alexander 

Plate 9, figure 6

The present example is believed to be somewhat distorted by compaction, but its main external features are 

as follows:

Shell elongate-subquadrate; much higher near anterior end than elsewhere; hinge margin long, slightly 

sinuous, with a strong anterocardinal elevation; ventral margin concave, perhaps as a result of distortion; 

anterior margin broadly rounded; posterior margin 

narrowly rounded, extended ventrally and bearing four

blunt spines. Left valve larger than right, extending 

beyond it in cardinal areas.

A broad marginal ridge begins anterodorsally on 

each valve, and occupies anterior end and anterior 

three-fourths of ventrum, terminating posteriorly in a 

low node; a low narrow ridge parallels hinge margin; 

anteromedially is a broad elongate swelling, posterior to 

which is a narrow, longitudinal, median ridge. A low 

eye tubercle occurs at anterodorsal angle. Posterior 

fifth of shell compressed. Smaller details of surface 

ornamentation obscured by recrystallization of shell 

material, but some portions are finely punctate.

Internal features not observed.

Length of a figured specimen 0.88 mm, height 0.41 

mm, thickness 0-30 mm.

Remarks: In its general outline, ventral extension of 

posterior margin, strong left valve overlap in ,the cardinal areas, and major surface ornamental features this 

species is much like C. fredericksburgensis Alexander 

(1929, p. 89) from the Fredericksburg group of northern Texas. Examples of that species kindly loaned 

by C. I. Alexander are higher with respect to length, 

have a more strongly elevated dorsal longitudinal ridge, 

a spinose anterior margin, and both coarse reticulations 

and fine pits covering the surface. The poor preservation of the present specimen prevents a complete understanding of its relationships.

Occurrence: Hatteras Light well No. 1, 7,310-7,320 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106947.

Cythereis? pamlicoensis Swain, n. sp. 

Plate 9, figure 4

Shell subquadrate in lateral view; highest near anterior end; hinge margin nearly straight, slightly more 

than four-fifths of shell length, with broadly obtuse 

cardinal angles; ventral margin nearly straight, posteriorly converging with dorsum; anterior margin 

broadly rounded, slightly extended below; posterior 

margin more narrowly rounded, slightly extended 

medially. Left valve larger than right, extending beyond the other along ventrum and in cardinal areas. 

Convexity of valves low, greatest thickness back of 

center.

Anterior end bears a marginal rim that is highest and 

broadest ventrally; posterior end and posterior twothirds of ventrum provided with a marginal rim that 

is broad and rather strongly elevated around postventral marginal bend; blunt projections, perhaps representing spines, occur on rims. Anterodorsally on each 

valve is an elongate swelling that probably represents 

an eye tubercle; a narrow ridge extends from anterior 

end of swelling nearly to midshell; two short spurs 

project from ventral flank of swelling. Mid-dorsally 

is a marginal ridge that bears three or four protuber-
MESOZOIC OSTRACODA 83

ances. About one-fifth frqm posterior end is a prominent transverse ridge that extends from dorsal margin 

to midheight. An obscure, narrow, longitudinal, 

ridgelike swelling begins at midheight about one-fourth 

from anterior end, converges slightly with dorsum in 

a posterior direction, and dies out about one-fourth 

from posterior end; a second obscure and shorter longitudinal swelling lies ventrad of midheight. General 

surface of valves coarsely and strongly reticulate.

Internal features not observed.

Length of holotype 0.74 mm, height 0.39 mm, thickness 0.24 mm.

Relationships: In general shape, reticulate surface 

and short transverse posterodorsal ridge G. pamlicoensis resembles C. austinensis Alexander (1929, p. 97) 

from the upper part of the Austin chalk of northern 

Texas, but the latter has a conspicuous median longitudinal ridge, whereas the corresponding feature in the 

present species is obscure. A posterodorsal transverse 

ridge, or plate, occurs in several species of Tertiary 

ostracodes including Trachyleberis stenzeli (Stephenson), T. exanthemata (Ulrich and Bassler), and 

Cythereis midwayensis Alexander, from the Gulf and 

Atlantic coastal regions.

Although its internal characteristics are unknown, 

the present species is tentatively placed in Cythereis 

because of its subquadrate outline and the organization 

of its surface features. It shows some relationship to 

Isocythereis Triebel (1940, p. 208) in outline, compressed valves, and posterodorsal ridge. That genus 

has broader inner lamellae, more numerous spots in the 

muscle scar, and simpler anterior hinge teeth and 

sockets than Cythereis Jones. Several species of Cretaceous ostracodes, including Cythereis austinensis 

Alexander, C. paraustinensis Swain, C. worthensis 

Alexander and the present one may prove to belong in 

Isocythereis when more is known about their internal 

structures^

Occurrence: Esso Standard Oil Co., North Carolina 

Esso No. 2, 2,310-2,320 feet, Peedee(?) formation, 

U.S.N.M. 106945.

Cythereis simulonuda Swain, n. sp. 

Plate 9, figures 32-34

Shell subquadrate in side view; highest about onefifth from anterior end; dorsal margin somewhat sinuous, with high anterocardinal projection formed by eye 

tubercle of left valve; ventral margin nearly straight, 

slightly sinuous; anterior margin broadly rounded, 

fringed with small spines, slightly truncate above; 

posterior margin acuminately pointed, strongly extended below, truncated above, and bearing several 

blunt spines or nodes. Left valve larger than right, 

extending beyond the other terminally and at cardinal 

angles.

Ends compressed; anterior margin bears a welldefined strongly elevated rim; posterior marginal rim 

less elevated. Midventral surface expanded to form 

short alae, surmounted by weakly serrate ridges that 

near their posterior termination bend dorsally for a 

short distance. Mid-dorsal margins bear serrate ridges 

that bend ventrad for a short distance near their posterior terminations. Hounded eye tubercles occur at 

anterocardinal angles. A low broad ridgelike longitudinal swelling occupies midportion of each valve. 

General surface smooth. Internal features not 

observed.

Length of holotype 0.95 mm, height 0.51 mm, thickness 0.44 mm.

Relationships: In general shape and surface ornamentation this species is close to C. ornatissima nuda 

Jones and Hinde from the Cenomanian (Lower Chalk) 

and perhaps younger Cretaceous of England (Jones 

and Hinde, 1890, p. 23). In that form, however, there 

is a prominent anteromedian node and postjacent short 

longitudinal ridge that are lacking in the present 

species.

Occurrence: Hatteras Light well No. 1, 4,780-4,790 

feet, beds of Eagle Ford(?) age, (U.S.N.M. 106966), 

5,340-5,350 feet, Tuscaloosa (?) formation (U.S.N.M. 

106965).

Cythereis bicornis Israelsky

Plate 9, figure 31

Cythereis Mcornis Israelsky, 1929, Arkansas Geol. Survey, Bull.

2, p. 19, pi. 4A, fig. 10.

Alexander, 1929, Texas Univ. Bull. 2907, p. 11, pi. 8, fig. 5. 

Swain, 1948, Maryland Dept. Geol., Mines, and Water Res., 

Bul. 2, p. 200, pi. 13, figs. 15, 16.

The external features of the species have been described in detail. The present specimens are entirely 

typical and nearly identical with specimens from the 

Brownstown marl of Arkansas kindly loaned by C. I. 

Alexander.

The hinge of the left valve consists of an anterior deep 

socket bearing a few coarse denticles, a postjacent high 

rounded nondenticulate tooth, an interterminal bar 

formed of the thickened valve edge, and a posterior 

socket partly obscured by matrix. Vestibule lacking, 

that is, the inner margin and line of concrescence coincide. Muscle scar not observed.

Length 0.63 mm, height 0.35 mm.

Occurrence: Hatteras Light well No. 1, 3,625 feet, 

Black Creek(?) formation; 4,320-4,330 feet, beds of 

Eagle Ford(?) age (U.S.N.M. 106964). The species 

also occurs in the Tokio and Brownstown formations of 

Arkansas, the lower part of the Taylor marl and upper 

part of the Austin chalk of northern Texas, and the 

lower part of the Matawan formation, subsurface, of 

Maryland.
84 OSTRACODA FROM WELLS IN NORTH CAROLINA

Cythereis quadrialira Swain, n. sp. 

Plate 9, figures 27-30

fArchicythereis" cf. Cythereis pidgeoni Schmidt, 1948, Jour. 

Paleontology, vol. 22, p. 417, pi. 62.

Shell subquadrate-acuminate in lateral view; highest 

about one-fifth from anterior end; hinge margin nearly 

straight, about two-thirds of shell length, with welldefined but broadly obtuse cardinal angles, anterior 

angle strongly extended; ventral margin nearly straight, 

slightly sinuous, subparallel to dorsum; anterior margin 

broadly rounded, finely spinose; posterior margin narrower, acuminately extended medially, and bearing 

several thick spines just below midheight. Left valve 

larger than right, extending beyond the other along 

ventrum and along dorsal slopes. Valves rather 

weakly convex, greatest thickness behind middle of 

shell.

Posterior fifth of shell strongly compressed. Ventral surface of each valve bears a narrow ridge, rising 

at posterior end and dying out about one-third from 

anterior end. Dorsad of this ridge, a second longitudinal ridge occupies middle three-fifths of valve, bears 

transverse grooves on its flanks in posterior portion, 

and bends obliquely toward dorsum near its posterior 

termination. A median narrow longitudinal ridge occupies middle three-fifths of valve, is thickened anterad 

of midshell (probably representing cythereisid submedian node) and at each of its ends; other minor 

thickened spots occur along ridge. Dorsomedian twofifths of valve bears a slightly serrate marginal ridge. 

Anterior end bears a narrow ridge lying a short distance 

within valve margin and terminating near anterocardinal angle in a rounded eye tubercle. General surface between ridges minutely pitted. Internal features 

not observed.

Length of holotype 0.68 mm, height 0.33 mm, thickness 0.29 mm.

Relationships: This species may not belong in Cythereis Jones, in which terminal hinge elements are crenulate, or in Trachyleberis Brady which lacks similar 

crenulation of the hinge teeth and sockets. The hinge 

of Cytliereis pidgeoni Berry, a closely related upper 

Cretaceous species, is not crenulate (Schmidt, 1948, pi. 

62, fig. 4) and a reassignment of it to Trachyleberis 

seems necessary. On the other hand Cythereis ~bonnemai Triebel from the Albian of Germany, also close 

to the present species, is said by Triebel (1940, p. 205) 

to have the hingement of Cythereis. The "Archicythereis" considered by Schmidt (1948, p. 417) to be a 

probable immature molt of "Cythereis" (Trachyleberis) pidgeoni seems identical with the present examples 

except for the presence of an oblique anterodorsal ridge 

not seen in the new species. Cythereis w\orthensis Alexander from the Fort Worth limestone (lower Washita)

of Texas has double ventral ridges rather than two more 

widely separated ventral ridges, and has stronger spurlike extensions from the median ridge than does the 

present form, but otherwise the two are closely similar. 

Occurrence: Hatteras Light well No. 1, 3,750-3,760 

feet, beds of Eutaw(?) age, U.S.N.M. 106962; North 

Carolina Esso No. 2,2,750-2,760 feet, beds of Eutaw( ?) 

age or Black Creek(?) formation, U.S.N.M. 106963.

Cythereis ornatissima (Reuss) 

Plate 9, figures 24-26

Cytlierina ornatissima Keuss, 1846, Verstein, bohm. Kreidef., pt.

2, p. 104, pi. 24, figs. 12, 18. 

Cytlierina ciliata Reuss, ibid., fig. 17. 

Cytlierina echinulata Williamson, 1847, Trans. Manchester Lit.

Phil. Soc., vol. 8, pi. 4, figs. 75, 76. 

Cytliereis ciliata, Jones, 1849, Monogr. Cret. Entom. Eng.,

Palaeontographical Soc. London, p. 19, pi. 4, figs, lla-h. 

Cypridina muricata Reuss, 1851, Haidinger's Nat. Abhandl., vol.

4, pt. 1, p. 50, pi. 5, figs. 12a-c. 

Cythere ornatissima (Reuss), Bosquet, 1854, Mem. Comm. Carte

Geol. Neerlande, vol. 2, pp. 107-110, pi. 9, figs. 6a-d. 

Cy there (Cythereis) ornatissima (Reuss) Williamson, 1872,

Trans. Lit. Phil. Soc. Manchester, ser. 3, vol. 5, p. 136. 

Cythereis ornatissima retieulata Jones and Hinde, 1890, SuppL

Monogr. Cret. Entom. Eng. and Ire., Palaeontographical

Soc. London, p. 24, pi. 1, figs. 67, 68, 77, pi. 4, figs. 9-12. 

Cythereis ornatissima, (Reuss), Chapman, 1917, Geol. Survey

Western Australia, Bull. 72, p. 55, pi. 14, fig. 10. 

Alexander, 1933, Jour Paleontology, vol. 7, p. 210, pi. 25,

fig. 18, pi. 26, figs lla, b, pi. 27, figs. 16a, b. 

Triebel, 1940, Senckenbergiana, vol. 22, p. 174, pi. 2, figs.

27-50. 

Sylvester-Bradley, 1948, Jour. Paleontology, vol. 22, p. 795,

pi. 122, figs. 20-22. 

Cythereis dallasensis Alexander, 1939, Texas Univ. Bull. 2907,

p. 99, pi. 8, figs. 8, 9.

Shell subquadrate in side view; highest about onesixth from anterior end; hinge margin nearly straight, 

about three-fourths of shell length; ventral margin 

slightly convex, subparallel to dorsum, but with slight 

posterior convergence; anterior margin broadly 

rounded, bearing one row of blunt spines in right valve, 

two rows in left; posterior margin narrower, bluntly 

acuminate medially, strongly truncate and slightly 

concave above, spinose below. Left valve larger than 

right, extending beyond the other terminally and at 

cardinal angles.

Anterior end somewhat compressed, bearing a narrow marginal rim on which occur the fringing marginal 

spines. Posterior fourth of shell compressed with narrow spinose marginal rims in ventral half. Midventral 

portion of each valve expanded, resulting in a pronounced flattening of midventral surface; a coarsely 

spinose longitudinal ridge extends along crest of ventral 

expansion. A large, rounded, spinose median node lies 

slightly anterad of midlength; behind node is a short 

longitudinal row of blunt spines. Along dorsal margin, 

a large bluntly spinose eye tubercle lies near antero-
MESOZOIC OSTEACODA 85

cardinal angle; a single short spine occurs near midleiigth and several short spines are present slightly 

anterad of postcardinal angle. General surface 

coarsely reticulate in posterior half, pustulose in anterior half. Internal features not observed in present 

specimens.

Length of figured specimen 0.85 mm, height 0.46 mm, 

thickness excluding spines, 0.39 mm.

Remarks: Possible topotype specimens of G. ornatissima from the Turonian of Bohemia were made available by C. I. Alexander. They are more completely 

reticulate than the North Carolina examples, but otherwise indistinguishable.

Occurrence: Hatteras Light well No. 1, 4,260-4,270 

feet, beds of Eutaw (?) age, and 4,410-4,420 feet, beds 

of Eagle Ford( ?) age, U.S.N.M. 106960. A specimen 

from the same well, 4,640-4,650 feet (pi. 2, fig. 26) in 

the beds of Eagle Ford( ?) age (U.S.N.M. 106961) has 

a very high aiiterocardinal angle and a more strongly 

expanded, subalate ventrum. This form resembles 

the more typical examples of "Gythereis ciliata" Jones 

( = G. omatissima (Reuss)) from the Cretaceous of 

England (Jones, 1849, pi. 4, figs, lla-d). It is uncertain whether these more strongly alate forms should be 

considered a distinct species or variety, or whether they 

are dimorphic examples of C. ornatissima.

Genus PROTOCYTHERE Triebel, 1938

Protocythere paratriplicata Swain, n. sp.

Plate 9, figure 18-21

ICythere foersteriana Bosquet, Alexander, 1929 Univ. Texas

Bull. 2907, p. 82, pi. 6, figs. 1, 11.

(Not) Bosquet, 1847, Mem. Soc. Roy. Sci. Liege, vol. 4, 

p. 364, pi. 2, figs. 4a-d.

Shell subpyriform in side view; highest about onefourth from anterior end; dorsal margin sinuous due to 

projection of surface of shell beyond hinge, medially, 

and to high anterocardinal projection of left valve; 

actual hinge margin nearly straight and about fourfifths of shell length; ventral margin gently converging 

posteriorly with dorsum; anterior margin broadly 

rounded, finely spinose on both valves; posterior margin 

acuminately pointed, truncate above, that of right 

valve bearing several small spines. Left valve larger 

than right, extending beyond the other along ventrum 

and at cardinal angles. Valves strongly convex, 

greatest thickness median.

Anterior fourth and posterior fifth of shell compressed. Median, more convex portion of each valve 

bears a dorsal, somewhat irregular longitudinal ridge 

that extends beyond line of valve contact medially; a 

median shorter longitudinal ridge; and a ventral longitudinal ridge that is swollen medially to overhang ventral edge. Between median and dorsal ridge and 

slightly anterad of midlength is a large depression, behind which are two pits. General surface smooth except for a few small pustules that mark position of some 

of the normal canals; most of canals not represented by 

such tubercles. Internal features not observed.

Length of holotype 0.70 mm, height 0.44 mm, thickness 0.37 mm.

Remarks: This form differs from P. triplicata (Jioemer) in having the posterior end of the left valve more 

acuminate, the longitudinal ridges less broad and the 

anterior margin of each valve denticulate. The examples from the Taylor marl of northern Texas identified by Alexander as Cythere-foersteriana Bosquet evidently belong with the present specimens. Although 

G. foersteriana is not completely understood it probably 

represents a Protocythere allied to P. triplicata but with 

the anterior end less broadly rounded. Earlier descriptions and illustrations of specimens assigned to 

P. triplicata (Jones, 1849, p. 18; Jones and Hinde, 

1840, p. 19) show surface pitting of the shell, but according to Triebel (1938, p. 182) the general shell surface is smooth.

Occurrence: The holotype is from the Hatteras Light 

well No. 1, 3,240-3,250 feet, Black Creek (?) formation 

(U.S.N.M. 106956). Paratype from 4,480-4,490 feet, 

Tuscaloosa formation (U.S.N.M. 106957).

Genus PTERYGOCYTHEREIS Blake, 1929

Pterygocythereis cf. P. tokiana (Israelsky)

Plate 9, Figures 1-3

Cytheropteron toJciana Israelsky, 1929, Arkansas Geol. Surv. 

BuU. 2 (Supplement), p. 9, pi. I A, figs. 8, 9.

Shell subquadrate in side view; highest near anterior 

end; dorsal margin nearly straight, except for high 

anterodorsal portion that projects beyond rest of margin; ventral margin nearly straight, converging 

slightly posterior toward dorsum; anterior margin 

broadly rounded, slightly extended below; posterior 

margin more narrowly rounded, sharply truncated 

above, extended medially. Left valve slightly larger 

than right and overlapping it.

Midventral portion of shell expanded to form distinct alae; ventral surface of each valve flattened and 

bearing a ridge parallel to margin. High narrow longitudinal ridges lie along crests of alae and extend toward 

anteroventral margin; dorsad of each ridge in anterior 

half is a broad groove. Behind anterodorsal angle is a 

shallow sulcus. Anterodorsal and anterior margin of 

each valve bears a finely denticulate narrow rim; eye 

tubercle interrupts this rim near, its anterodorsal 

termination. Posterior valve margins provided with 

narrow rims that bear about six or seven short thick 

spines in ventral two-thirds and at postdorsal angle. 

Mid-dorsally is a short, longitudinal, somewhat serrate 

ridge. General surface of valves smooth.
86 OSTRACODA FROM WELLS IN NORTH CAROLINA

Most internal features not observable. Muscle scar 

as seen by reflected light in one specimen consists of an 

anteromedian subvertical row of perhaps four spots 

and an additional more anterior, horseshoe-shaped spot.

Length of a figured specimen (pi. 9, fig. 1) 0.85 mm, 

height 0.40 mm, thickness 0.40 mm (including alae).

Remarks: In its subquadrate outline, conspicuous 

alae with superposed longitudinal ridges, and the 

spinose margins the present examples are like Cytheropteron tokiana Israelsky from the Upper Cretaceous 

Tokio formation of Arkansas. As illustrated by 

Israelsky (1929, pi. IA, figs. 8, 9) the species lacks the 

sharp truncation along the postdorsal slope that characterizes the present forms. The straight hinge and 

lack of conspicuous posterior caudal extension ally the 

species to Pterygocythereis Blake rather than to 

Cytheropteron Sars.

Occurrence: Hatteras Light well No. 1, 4,440-4,450, 

beds of Eagle Ford(?) age (U.S.N.M. 106944) and 

6,310-6,320 feet, beds of Trinity (?) and pre-Trinity (?) 

uge undifferentiated (U.S.N.M. 106943).

Genus CYTHEROPTERON Sars, 1865

Subgenus EOCYTHEROPTERON Alexander, 1933

Cytheropteron (Eocytheropteron) tumoides Swain, n. sp.

Plate 9, figures 7, 8

Shell ovate-acuminate in lateral view; highest 

slightly anterad of midlength; dorsal margin moderately convex; ventral margin gently convex; anterior 

margin broadly rounded, slightly extended below midheight; posterior margin narrowly rounded with a 

slightly ventromedian, bluntly pointed, compressed 

caudate extension. Left valve a little larger than right, 

extending beyond the other along dorsal and anterior 

margins.

Ventral half of valves strongly swollen to form 

rounded alate expansions; along ventrum, surface 

slightly overhangs valve margins. Anterior edge of 

right valve bears a narrow weak marginal rim; a broad, 

shallow, curved depression lies parallel to anterior 

margin in dorsal half to three-fifths of valves; behind 

this depression in dorsal half of each valve is a subvertical low ridge that merges with general surface 

ventrally; behind ridge in dorsal two-fifths of valve is 

a broad, rounded, very shallow depression. Ventral 

portion of shell bears weak longitudinal striae, and 

median portion is ornamented by weak markings in a 

pseudoreticulate pattern.

Internal features not observed.

Length of holotype, believed to represent a female 

dimorph 0.88 mm, height 0.50 mm, thickness 0.47 mm.

Relationships: In general shape, overlap relationships, rounded alate expansions and median position of 

the posterior caudate extension, this species is similar to 

0. (Eocytheropteron) tumidum Alexander from the

Kiamichi formation and underlying Goodland limestone of northern Texas (Alexander, 1933, p. 198). 

That species, however, lacks the aiiterodorsal shallow 

depressions and ridge of the present form, and the 

ventral margin is more convex. C. (E.) paenorbiculatmn Alexander (1933, p. 197) from the same stratigraphic horizons in Texas bears a shallow dorsomedian 

depression like that in the new species but the left valve 

extends strongly beyond the right along the dorsum.

Occurrence: Hatteras Light well No. 1, 6,340-6,350 

feet (U.S.N.M 106949) and 6,760-6,770 feet (U.S.N.M. 

106948), beds of Trinity (?) and pre-Trinity (?) age, 

undifferentiated.

Cytheropteron (Eocytheropteron) trinitiensis (Vanderpool)

Plate 9, figures 9, 10

Cytheridea trinitiensis Vanderprool, 1928, Jour. Paleontology,

vol. 2, p. 106, pi. 14, figs. 3-6. 

Cytheropteron (Eocytheropteron) trinitiensis (Vanderpool),

Vanderpool, 1933, Jour. Paleontology, vol. 7, p. 410, pi. 49,

figs. 16-19.

Shell subhemispherical in side view; highest medially ; dorsal margin strongly convex; ventral margin 

slightly convex; anterior end broadly rounded, slightly 

extended and angulate at its ventral bend; posterior 

margin somewhat more narrowly rounded, with a 

median, very short compressed caudate extension. Left 

valve slightly larger than right, extending beyond the 

other along dorsum.

Ventral portions of valves strongly swollen as short 

alate expansions that slightly overhang ventral edges 

of valves; ventral surface of shell slightly concave in 

end view. Crest of each ala bears a low longitudinal 

ridge; dorsad of this ridge in ventral half of shell 

are four short, low longitudinal ridges. General surface very weakly punctate. Internal features not 

observed.

Length of figured specimen, possibly a female dimorph, 0.68 mm, height 0.47 mm, thickness 0.44 mm.

Relationships: The present examples were compared 

with Vanderpool's types from the Glen Rose formation of Texas, and found to be conspecific. Among 

other described species, Cytheropteron (Eocytheropteron) howelli Alexander (1933, p. 196) from the Goodland and Kiamichi formations of Texas is close to C. 

(E.} trinitiensis in outline, character of the alae and 

presence of a low ventral longitudinal ridge along the 

crest of each ala. However, the posterior caudate extension of that species is slightly longer and the ventral 

ridge is more strongly elevated and bears several large 

pits on its dorsal flank.

Occurrence: Hatteras Light well No. 1, 6,170-6,180 

feet and below, beds of Trinity (?) and pre-Trinity (?) 

age, undifferentiated. The figured specimen' is from a 

drill-cutting sample 6,340-6,350 feet (U.S.N.M. 

106950).
MESOZOIC OSTEACODA 87

Cytheropteron (Eocytheropteron) acaudatum Swain, n. sp. 

Plate 9, figures 15, 16

Shell small, subovate in side view; highest about 

three-eighths from anterior end; dorsal margin moderately convex, steeper in front of position of greatest 

height than behind; ventral margin slightly convex; 

anterior margin broadly rounded, extended below; posterior margin more narrowly rounded, slightly extended medially. Left valve slightly larger than right.

Ventral surface of shell greatly expanded, strongly 

overhanging edges of valves along midportion of ventrum. Median portion of anterior end of right valve 

bears a shallow groove parallel to margin. General 

surface of shell bears obscure concentrically arranged 

grooves and intervening ridges, together with very 

weak, widely spaced large pits. Internal features not 

observed.

Length of holotype 0.55 mm, height 0.33 mm, thickness 0.30 mm.

Relationships: In its lack of a caudate extension of 

the posterior end, and surface ornamentation, this species is close to undescribed examples of C. (Eocytheropteron) from the Schuler formation, Upper Jurassic of 

Louisiana (Swain, 1949, pi. 3, figs. 11-13). The Jurassic forms, however, are more convex dorsally and bear 

well-defined longitudinal ridges along the flattened 

ventrum.

Occurrence: Hatteras Light well No. 1, 5,640-5,650 

feet, beds of Washita( ?) age U.S.N.M. 106954.

Genus KRITHE Brady, Grosskey and Eobertson, 1874

Xrithe cf. K. postprojecta Schmidt

Plate 9, figure 11

Krithe postprojecta Schmidt, 1948, Jour. Paleontology, vol. 22, 

p. 409, pi. 61, fig. 8, text fig. 2d.

Shell subelliptical in side view; dorsal margin 

slightly convex; ventral margin nearly straight and 

subparallel to dorsum; anterior margin uniformly 

rounded; posterior margin slightly narrower, extended 

ventrally and subtruncate above. Left valve slightly 

larger than right, extending beyond the other, except 

posteriorly. Valves rather weakly convex, greatest 

thickness in posterior third. Surface smooth.

As viewed posteriorly, posteroventral end of each 

valve projects slightly beyond contact-line of valves. 

On either side of contact line, midportion of posterior 

end of each valve bears an oval pit which is bordered 

by a slight ridgelike thickening of the valve. Internal 

features not seen.

Length of figured specimen 0.66 mm, height 0.30 mm, 

thickness 0.24 mm.

Remarks: In general outline and left valve overlap 

this species conforms with features prescribed for 

Krithe. All of the species at present assigned to the 

genus differ only in small details of outline and of the

posterior end of the shell. The present example is close 

to K. postprojecta Schmidt, although that form possibly is more extended posteroventrally and the terminal 

posterior pits were not mentioned in the original description (Schmidt, 1948, p. 409).

Occurrence: North Carolina Esso well No. 2, 2,300- 

2,310 feet, Peedee( ?) formation, U.S.N.M. 106951.

Genus GOMPHOCYTHEEE Sars, 1924

Gomphocythere? cf. G. silvana Martin

Plate 9, figure 23

Gomphocythere silvana Martin, 1940, Senckenbergiana, vol. 22, 

p. 345, pi. 6, figs. 87, 88, pi. 9, figs. 144-147, pi. 12, fig. 175.

Shell small, subquadrate in side view; greatest height 

about one-fourth from anterior end; hinge margin 

nearly straight, about two-thirds of shell length; anterior cardinal angle widely obtuse, posterior cardinal 

angle only slightly obtuse; ventral margin slightly convex, converging posteriorly toward dorsum; anterior 

margin broadly rounded, slightly truncated above; posterior margin more narrowly rounded, slightly extended above. Left valve slightly larger than right, 

extending beyond it along dorsum. Convexity of valves 

low, greatest thickness in posterior third of shell.

Anterodorsal surface of each valve folded into two 

short subvertical shallow sulci and intervening 

rounded low lobe. Posterodorsal corner of shell compressed. In single specimen at hand general surface 

is too poorly preserved to retain other details. Internal 

features not observed.

Length 0.51 mm, height 0.32 mm, thickness 0.20 mm.

Remarks: In external shell characteristics the present 

form closely resembles Gomphocythere sibvana Martin 

from the Wealden beds (Neocomian) of northern Germany. The surface pitting of the Wealden examples 

could not be segn in this specimen, perhaps because of 

its poor preservation. The Wealden specimens also 

bear a post-median node or short spine on each valve, 

a feature not identified with certainty on the present 

example, although there is a small elevation on the 

right valve that is probably extraneous material. The 

bisulcate, straight-hinged character of the present form 

causes it to resemble Hutsonia Swain (1946) from the 

Upper Jurassic, Jonesina Ulrich and Bassler (1908) 

from the late Paleozoic, and Ilyocypris Brady and 

Norman (1889) from the Cenozoic. Hutsonia typically 

is more acuminate posteriorly and has a distinct marginal rim. Ilyocypris and Jonesina can be distinguished 

from each other mainly on the basis of hingement and 

musculature, although these features in Jonesina are 

not clearly understood. As viewed dorsally, Jonesina 

has the anterior portion of the hingeline obscurely cardine, a feature apparently lacking in Ilyocypris. Gomphocythere Sars (1924) was established for straighthinged, unisulcate or bisulcate Ostracoda with the posterior portion of the shell, even in male dimorphs.
OSTRACODA FROM WELLS IN NORTH CAROLINA

swollen, features that are reminiscent of Metacypris 

Brady and Robertson (1870). The distinction between 

the two genera is not clearly understood, and G. silvana, 

lacking the posterior tumidity, can be assigned only 

tentatively to this genus.

Occurrence: Hatteras Light well No. 1, 8,430-8,440 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106959.

Genus MONOCERATINA Roth, 1928

Monoceratina sp. aff. M. semiornata Alexander

Plate 9, figures 12,13

The single, incomplete specimen at hand exhibits the 

following characteristics.

Shell subquadrate in lateral view; highest near anterior end; hinge margin nearly straight, more than threefourths of shell length, with well-defined, obtuse cardinal angles; ventral margin gently convex, converging 

posteriorly toward dorsum; anterior margin broadly 

rounded, forming an obtuse angle with ventral margin, 

approximately equal to corresponding cardinal angle; 

posterior margin narrowly rounded with the stump of 

a broad caudate extension dorsad of midheight. Left 

valve extends slightly beyond right anteriorly and ventrally; dorsally, right valve projects slightly beyond 

left. Valves not, strongly convex; thickest portion of 

shell slightly posteromedian at position of spinose 

expansions of shell.

Dorsal margin of each valve bears a narrow marginal 

rim that dies out in posterior third of shell, and is 

elevated to form a small protuberance at anterior cardinal angle; anterior margin provided with very narrow 

rimlike elevation; ventral margins have rims that are 

broad posteriorly, narrow medially, and broader and 

more strongly elevated in anterior fourth. Ends compressed. Anteromedian'surface of ea^h valve swollen 

to form a rounded lobe; between lobe and midlength 

is a deep vertical sulcus that opens on dorsum and 

terminates ventrally at midheight; surface postventrad 

of sulcus imperfect in each valve but elevations of surface just behind ventral end of sulci probably represent bases of spinose projections characteristic of this 

group of ostracodes. General surface of each valve, 

except sulcus and marginal rims pitted in a reticulate 

pattern, with some dominant elements of the reticulum 

oriented concentrically about sulcus.

Internal characteristics mostly not observed. Muscle 

scar consists in part of a sub vertical row of three or four 

longitudinally elongated spots lying near ventral end 

of median sulcus.

Length of a figured specimen 0.55 mm, height 0.27 

mm, thickness, excluding ala involved in spinose expansion which is incomplete, 0.23 mm.

Remarks: In shape, surface pitting and sulcation of 

the shell this form is similar to M. semiornata Alexander (1933, p. 63) from the upper part of the Austin 

chalk, Travis County, Tex. That species differs in 

bearing a broad, denticulate, anterior marginal rim, a 

dorsal longitudinal ridge in posterior half of shell, and 

in lacking surface pits in the posterior portion. M. 

umbonata Alexander (1933, p. 62) from the Navarro 

group and Taylor marl of northern Texas has the entire 

surface pitted, but has a rather weak median sulcus. 

The present example perhaps lies midway between these 

two species with respect to its shell characteristics, but 

its poor preservation precludes accurate classification. 

Occurrence: Hatteras Light well No. 1, 3,800-3,810 

feet, beds of Eutaw(?) age, U.S.N.M. 106952.

Genus HTTTSONIA Swain, 1946

Hutsonia? microrugosa Swain, n. sp.

Plate 9, figure 14

Shell minute, subquadrate in side view; highest about 

one-fourth from anterior end; hinge margin nearly 

straight with slight elevation at anterior cardinal angle, 

about two-thirds of shell length; ventral margin nearly 

straight for two-thirds of its length, bending abruptly 

into ventral portion of posterior margin; anterior margin broadly rounded, truncated above; posterior margin 

narrowly rounded, extended medially, strongly truncate below. Valves approximately equal in size, 

strongly compressed.

Anterior end and ventral portion of posterior end 

in each valve bear narrow marginal rims. A broad verticle sulcus lies slightly antrad of midlength and extends 

from dorsum to about one-third from ventral margin; 

a second shorter sulcus, separated from the preceding 

by a rounded lobe, extends anteroventrally from anterior cardinal angle; posterior to median sulcus is a 

third short, vertical sulcus, bounded on its posterior 

side by a low rounded node. A narrow longitudinal 

ridge lies in posterior two-thirds of shell, about onethird of shell height from ventral margin. General 

surface of shell roughly sculptured with irregular elevations and depressions, and in some portions minute 

pits. Internal features not seen.

Length 0.41 mm, height 0.21 mm, thickness 0.01 mm.

Relationships: The subquadrate outline, sulcation, 

and ventral longitudinal ridge ally this form to Hutsonia Swain, but lack of knowledge of the internal 

features prevents definite generic classification. It 

resembles Hutsonia rugosa Swain (1946, p. 129) in 

sulcation and general rugose surface but that species has 

the posterior portion of the shell rather strongly inflated with respect to the anterior portion, a long anterior sulcus, and a broad rimlike elevation of the 

anterior end.

Occurrence: Hatteras Light well No. 1, 6,260-6,270 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106953.
MESOZOIC OSTRACODA 89

Genus MACRODENTINA Martin, 1940

Macrodentina? obliqua Swain, n. sp.

Plate 9, figure 17

The holotype, a right valve, subovate in side view; 

highest about one-fourth from anterior end; hinge 

margin nearly straight, about two-thirds of shell length; 

ventral margin gently convex converging with dorsum 

in a posterior direction; anterior margin broadly 

rounded, extended below, and passing with sharp curvature into ventral margin; posterior margin narrowly 

rounded, extended above midheight, passing uniformly 

into ventral margin. Overlap relationships unknown. 

Right valve moderately convex, greatest thickness in 

posterior and ventral portions; along posterior twothirds of ventrmn surface of valve overhangs margin.

A short sulcus begins near anterior cardinal angle and 

trends subparallel to anterior margin approximately to 

midheight. A large rounded pit occurs slightly below 

midheight and about one-fourth from anterior end. 

Ventral portion of valve bears coarse concentric ridges 

with intervening pitted grooves; anterior and anteroventral portions bfear three especially strong concentric 

ridges; dorsal portion coarsely pitted.

Internal features not observable in the one specimen 

at hand.

Length 0.54 mm, height 0.33 mm.

Relationships: The general ovoid shape and concentric ornamentation of this species ally it with Loxocancha Sars, but the strong anterior and ventral concentric 

ridges perhaps indicate a closer relationship to Macrodentina Martin. A closely similar if not identical 

species from the Cotton Valley group, Upper Jurassic 

of Louisiana was referred to as Loxoconcha? sp. (Swain, 

1949, pi. 3, fig. 28).

Occiifrrence: Hatteras Light well No. 1, 8,330-8,340 

feet, beds of Trinity (?) and pre-Trinity (?) age, undifferentiated, U.S.N.M. 106955.

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90 OSTRACODA FROM WELLS IN NORTH CAROLINA

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INDEX

[Italic numbers indicate descriptions] 

A

acaudatum, Cytheropteron (Eocytheropteron) ________ 64, 69, 87, pi. 9

Acknowledgements for aid._______________________ 59 

acuminata, Asciocythere________________________ 63, 69, 77, 78, pi. 8

Schuleridea____________________________ 66, 69, 72, 74, 75, pi. 9

alexandrina, Bairdia______________________ 63, 69, 71, pi. 8 

amygdaloides, Asciocythere_____________________ 64, 69, 76, 78, pi. 8

Cythere_______________________——____________ 76, 77

Cytherella ________—————————_______________ 76

Haplocytheridea ________—___________________ 76

amygdaloides brevis, Cythere_______________________________ 76

Cytheridea ________________________________——_—— 76

Cytheridea (HaplocytherideaT) ____________________ 76

Apatocythere——_—______________________ 59, 78, 73, 77

ellipsoidea __—____________________________ 73 

lanceolata_____________________ 65, 67, 69, 72, 73, pi. 9

leguminoidea______________________________ 64, 66, 69, 73, pi. 9

simulans_____________________________________________ 72, 73

tumidosa-__________________________ 65, 67, 69, 75, pi. 9

arachoides, Brachycythere__________________________ 67, 69, 81, pi. 9

Cythere ________________——_______________ 81

area, Globotruncana_______________________________________ 62, 67

"Archicythereis" cf. Cythereis pidgeoni—_______________ 84

Asciocythere____________—____________________ 59, 75, 78

acuminata________________________________ 63, 69, 77, 78, pi. 8

amygdaloides______________________________ 64, 69, 76, 78, pi. 8

leguminoides______——______________ 64, 66, 69, 78, pi. 8

macropunctata___________________________ 63, 69, 77, pi. 8

rotunda_____——___________________ 64, 69, 76, 77, pi. 8

triangularis___________—_—__________ 64, 69, 77, pi. 8

Atopochara sp__________——————————————__—_—__ 68

austinensis, Cythereis_____________________________________ 83

Cytherella —__________________________________ 68

Bairdia-_________________________________________________ 59, 71

alexandrina_____________—————________ 63, 69, 71, pi. 8

subdeltoidea__________________________________________ 71

Bairdiidae ________________________________ 69, 71-72 

Bairdiocypris-_________—_______________________ 59

morrisonensis ___________________%______________ 72

sp————————————————————————_________ 69, 72, pi. 8 

Bairdopillata_____________________________________________ 59, 71

pondera-_____—_—__________________ 62, 69, 71, pi. 8

berryi, Haplocytheridea_________________________ 62, 69, 78, 79, pi. 8

bicomis, Cythereis_____________—_________ 62, 63, 69, 85, pi. 9

Black Creek formation______________________ 59, 61, 62, 67 

bonnemai, Cythereis_________________________________ 84

Brachycythere——_____________—__—_____________ 59, 80, 81

arachoides___________________________________ 67, 69, 81, pi. 9

darensis___——_——____——__——_—_____— 62, 69, 80, pi. 8

hadleyi ______________________—____________ 80

infundibuliformis _____________________________________ 81

jerseyensis_______—____—__—_____________ 81

nausiformis____________________________ 62, 63, 67, 69, 80, pi. 8

sphenoides_——__————_——__________ 62, 69, 80, 81, pi. 8

taylorensis_________________________________________ 80

brevis, Cythere amygdaloides_______________________________ 76

Cytheridea amygdaloides_________——_________——— 76

Cytheridea (HaplocytherideaT) amygdaloides_________—__ 76

Bythocypris rotundus________________—_____________ 75, 76

cancellata, Exogyra__________———_——___—'. _________ 72

castleberryensis, Cytherelloidea—___—_—_______——_—— 70

Choffatellat___________1—_—___________________—— 66

christneri, Kyphopytea_____________________________________ 62, 67

ciliata, Cythereis_______________———_—______——_— 84

Cytherina____—_______——___—____________ 84

Clithrocytheridea _________________________________ 74, 75

concentricum, Cytheropteron_____—______________— 70

concentricum virginea, Cytheropteron________________________ 70

Cypridae __________—__————————————————— 69, 70-71 

Cypridea________—————————————————————————————— 75

Cypridina muricata______————_—————————————————— 84

Cypris———————————————————————————————— 59,70

sp_________________________________ 64, 69, 70, pi. 8 

Cythere amygdaloides___________—_—_—————————————— 76, 77

amygdaloides brevis______————————————————————— 76

arachoides ___———————————————————————————— 81 

foersteriana____———————————————————————————— 85

omatissima ___———————————————————————————— 84 

rectangulapora- _______________————————————————— 81

sphenoides____————————_——_———————————————— 80

(Cythereis) omatisssima-__________-_____——-———___-- 84

Cythereis ———————————————— ———— ———————————— 59, 81

austinensis__________———————————————————————— 83

bicornis__________________________———— 62, 63, 69, 85, pi. 9

bonnemai ______——_———————————————————————— 84

ciliata____________————————————————————————— 84

dallasensis______——————————————————————————— 84

elegans _—_———————————————————————————— 82 

fredericksburgensis_______—__———————— 65, 69, 82, pi. 9 

midwayensis _——————————————————————————— 83 

ornatissima___________________—__ 63, 69, 84, 85, pi. 9 

omatissima nuda_____—___———————————————— 83 

ornatissima reticulata—_____————————————————— 84 

pamlicoensis________________________ 67, 69, 82, 83, pi. 9

paraustinensis—————_——————————————————————— 83

pidgeoni————————————————————————————————— 84

pidgeoni, cf. "Archicythereis"__—__—_—_—————— 84

quadrialira_____________;__—__— 63, 67, 69, 84, pi. 9

rugosissima__________—______————— 63, 69, 81, pi. 9

simulonuda______________-_———————— 63, 69, 83, pi. 9

worthensis—_———————————————————————————— 83, 84

(Cythereis) ornatissima, Cythere-——_——————————————— 84

Cytherellidae___________________________—__ 68, 69, 70

Cytherella_____________________________ 59, 68, 70, 77

amygdaloides_————_——_————————_____—————— 76

austinensis ——_———————————————————————————— 68 

navarroensis-———_______——_—___—__ 62, 68, 69, pi. 8 

obesa____________________—_______ 62, 68, 69, pi. 8 

ovata ——————————————_————_———————— 76

ovoidea_______________———_————————————— 68 

Cytherelloidea—————————————————————___—— 59, 70

castleberryensis ———_———————————_——————————— 70 

darensis———————————————————__—— 65, 68, 69, pi. 8

granulosa——————————————————————————— 70

howei _____—————__—————————————————————— 70 

reticulata——————————————————————————— 70

Cytheridae________————————-———————————————— 69, 72

Cytheridea______——___————_————————————————— 77 

amygdaloides brevis————————————————————— 76

fortior ———_————_———————————————————————— 76 

graysonensis ————————————————————————————— 78 

Umburgensis •.————————————————————————————— 76 

monmouthensis———————————————————————————— 79 

ovata -————-———————_—————————————————— 77, 78

plummeri————_—————————————————————————— 79, 80 

reniformis —————————————_——_————————————— 76 

rotundus _——————————————————————————————— 76 

trinitiensis———————————————————————————— 86

sp ————————————————————————— .________________—____—_________ 78

Cytheridea (Haplocytheridea) monmouthensis.

thorensis —————————————————————

amygdaloides brevis———————————

Cytherina ciliata————————————————

echinulata __————————————————— 

ornatissima—————————————————

Cytherissa __————————————————————

_________ 79

._______ 74

________ 76

_______ 84

_______ 84

.——————— 84

_______ 75

Cytheropteron———————————————————————————————— 59, 86

concentricum————————————————————————— 70

virginea——————_____—____—_————————————— 70

sphenoides —_————_——___————————————————— 80

tokiana—————————————————————————————————— 85

sp. B___________________—______——————— 80

91
92 INDEX

Cytheropteron (Eocytheropteron) acaudatum________ 64, 69, 87, pi. 9

howelli______________________________________________ 86

paenorbiculatum_______________________________ 86

trinitiensis_____..___________________ 64, 69, 86, pi. 9

tumidum_______________________________ 60, 64, 86 

tiimoides_____________________________________ 64, 69, 86, pi. 9

dallasensis, Cythereis_______________________________ 84

darensis, Brachycythere__________________________ 62, 69, 80, pi. 8

Cytherelloidea________________________________ 65, 68, 69, pi. 8

B

Eagle Ford formation________________________ 59, 61, 62, 67 

echinulata, Cytherina___________________________ 84

elegans, Cythercis _________________________________________ 82

ellipsoidea, Apatocythere____________________________ 73

Eocytheropteron_________________________________ 59, 86

(Eocytheropteron) acaudatum, Cytheropteron_________ 64, 69, 87, pi. 9

howelli, Cytheropteron_________________________ 86 

paenofbiculatum, Cytheropteron__________________ 86

trinitiensis, Cytheropteron_______________ 64, 69, 86, pi. 9

tumidum, Cytheropteron_____________________ 60, 64, 86

tumoides, Cytheropteron_—______________ 64, 69, 86, pi. 9 

Eutaw formation__——————______———________ 59, 61, 62, 63, 67

exanthemata, Trachyleberis________________________________ 83

Exogyra cancellata___________________—______________ 72

F

fortior, Cytheridea___________________________________ 76

foersteriana, Cythere_________——__——_——__________ 85

Fredericksburg formation______________________ 59, 60, 61, 64 

fredericksburgensis, Cythereis______——_———____ 65, 69, 82, pi. 9

G

G-lobotruncana area—————__——————————————————_——— 62, 67 

Q-omphocythere_______————————————————————————_— 59, 87

silvana_________________________________________ 69, 87, pi. 9

granulosa, Cytherelloidea___________________________________ 70

graysonensis, Cytheridea_____—_——————————_——————___ 78

Haplocytheridea___________________________ 63, 69, 78, pi. 8

H

hadleyi, Brachycythere-—______———_———_——————_____ 80

Haplocytheridea_________________________________- 59, 72, 75, 78

amygdaloides_—————————————————————————————— 76

berryi____________________________ 62, 69, 78, 79, pi. 8

graysonensis______________——_———————————— 63, 69, 78, pi. 8

monmouthensis____————————————————————— 67, 69, 79, pi. 8

plummeri_____________________________——_ 62, 63, 69, 79, pi. 8

(Haplocytheridea f) amygdaloides brevis, Cytheridea_________ 76

monmouthensis, Cytheridea__________—__—______ 79

thorensis, Cytheridea_____—___—————————————__—_ 74

hatterasensis, Schuleridea____________________ 64, 67, 69, 74, 75, pi. 9

howei, Cytherelloidea____________——————————————__—— 70

howelli, Cytheropteron (Eocytheropteron) ________________——— 86

Hutsonia________________________________,,__ 59, 87, 88 

microrugosa____________________—____—-—— 64, 69, 88, pi. 9

Ilyocypris______________________________________ 59, 70, 71, 75, 87

tumida____________________________ 64, 69, 70, pi. 8 

infundibuliformis, Brachycythere____________________________ 81

Inoceramus _____——_———————————————————————————— 62

Introduction __________—————————————————————— 59 

Isocythereis—___————_——-————————————————————— 83

jerseyensis, Brachycythere_____———————————————————— 81

Jonesina__________________—————————————————————— 87

Jurassic, late__________________——_____———————— 61, 62

Krithe ___________________———__——————————— 59, 87 

postprojecta_______________________________———— 67, 69, 87, pi. 9

Kyphopyaa christneri_____________________———————___ 62, 67

lacustris, Schuleridea___________________________ 67, 74, pi. 9

lanceolata, Apatocythere___________________ 65, 67, 69, 72, 73, pi. 9

legmnlnoidea, Apatocythere- __________________ 64, 66, 69, 73, pi. 9

leouminoides, Asciocythere_______________ 64, 66, 69, 78, pi. 8

limburgensis, Cytheridea_________________________ 76

Losnoconcha ___________________________________ 89

M

Macrodentina __________________________________ 59, 89

obliqua_______________________________ 66, 69, 89, pi. 9

macropunctata, Asciocythere___________________ 63, 69, 77, pi. 8

Metacypris_______———___—_____________________— 75, 88

ventrosa__________________________________ 71 

microrugosa, Hutsonia______________________ 64, 69, 88, pi. 9

midwayensis, Cythereis_______________________________ 83

monmouthensis, Cytheridea__________________________ 79

Cytheridea (Haplocytheridea) __________________________ 79

Haplocytheridea__________________________ 67, 69, 79, pi. 8

Monoceratina _____—_________________________——— 59, 88

semiornata_______________________________ 63, 69, 88, pi. 9

umbonata——________________________—__ 88

morrisonensis, Bairdiocypris. 

muricata, Cypridina_______

72

84

N

nnusiformis, Brachycythere______________ 62, 63, 67, 69, 80, pi. 8 

navarroensis, Cytherella____—_____________ 62, 68, 69, pi. 8 

nuda, Cythereis ornatissima_________________________ 83

obesa, Cytherella-———_——————_________—_—_ 62, 68, 69, pi. &

obliqtia, Macrodentina--————_——_________—_ 66, 69, 89, pi. 9

ornatissima, Cythere______—_____—__—_—_____ 84

Cythere (Cythereis) ————————__——_——————————— 84

Cythereis__________________________ 63, 69, 84, 85, pi. 9

Cytherina__________________________—______ 84

nuda, Cythereis_______——_____________————— 83

reticulata, Cythereis_______________—___——— 84

ovata, Cytherella--——_—_——__——_————————————— 76

Cytheridea__________________________________ 77, 78

ovoidea, Cytherella—————————————_——————————————— 68

Paleocene_———— ——— ————— —————————————————————— 61 

pamlicoensis, Cythereis____——______—__——- 67, 69, 82, pi. 9 

Paracypris___•_______________________——————— 59, 70

sp_________________________________ 65, 69, 70, pi. 8 

paratriplicata, Protocythere__——————_————————— 62, 69, 85, pi. 9 

paraustinensis, Cythereis___—______—___—————_—_—— 83

Peedee formation______________________———— 59, 61, 62, 67 

pentagonalis, Schuleridea____—______——————— 66, 69, 75, pi. 9 

pidgeoni, Archicythereis cf. Cythereis—————————————————— 84

Cythereis _——————————————————————————————— 84

Cythereis cf. "Archicythereis"-——————————————————— 84 

Planulina taylorensis— —— —————————— ——————————— ——— 62, 67 

Platycopa__________ —————— __————————————————— 68-70 

plummeri, Cytheridea—_—————————————————————————— 79, 80

Haplocytheridea__________________——— 62, 63, 69, 79, pi. 8 

Podocopa ______________——____——————————————— 70-90 

pondera, Bairdopillata______________——__———— 62, 69, 71, pi. 8 

postprojecta, Krithe__________________—————— 67, 69, 87, pi. 9 

Pre-Cambrian____—_———_—————————————————— 59, 60, 66, 67 

Protocythere__________________————————————— 59, 81, 85

paratriplicata__________________——————— 62, 69, 85, pi. 9

triplicata __———————————————————————————————— 85 

Pterygocythereis———_————— — —————————————————— 59, 85, 86

tokiana___________———__—————— 63, 64, 69, 85, 86, pi. 9

Q

guadrialira, Cythereis __——————————————— 63, 67, 69, 84, pi. 9
INDEX 93

rectangulapora, Cythere-____——___________—_____ 81

References___________—____________________ 89

regina, Vaginulina__________—________________ 62, 67

reniformis, Cytheridea- ___——____———_———_——_—____ 76

reticulata, Cythereis ornatissima_____________—_——————— 84

Cytherelloidea_____________—___————_———_———— 70

rotunda, Asciocythere__——_——__——______ 64, 69, 76, 77, pi. 8 

rotundus, Bythocypris____________—_—___———_—— 75, 76

Cytheridea________________________———————— 76

______________________ 63, 69, 81, pi. 9

S

Schuler formation____________—_—_————_—_————— 59, 66 

Schuleridea________________________________________ 59, 72, 73, 74

acuminata______________________ 66, 69, 72, 74, 75, pi. 9 

hatterasensis___________________________ 64, 67, 69, 74, 75, pi. 9

lacustris_______________..____—______——_——— 67, 74, pi. 9

pentagonalis______________________—— 66, 69, 75, pi. 9

umbonata_________——————_——_——————————————— 72, 74

semiornata, Monoceratina______——______—__ 63, 69, 88, pi. 9

silvana, Gomphocythere-—_——_—_—_—____———_— 69, 87, pi. 9 

simulans, Apatocythere-—___———————_———_——___—_— 72, 73 

simulonuda, Cythereis-.-____—————————_—_____ 63, 69, 83, pi. 9

sphenoides, Brachycythere_—___——________ 62, 69, 80, 81, pi. 8

Cythere _______________________________________ 80

Cytheropteron________________________________________ 80

stenseli, Trachyleberis___________________________ 83

Stratigraphic section, well no. 1______________________ 61-67

well no. 2_—_____________________________ 61, 67-68

subdeltoi&ea, Bairdia_______________________________ 71

Summary, stratigraphic——__________________________ 59

taylorensis, Brachycythere-—_—_—____——_—_—_—_——_ 80 

Planulina____________________________________________ 62, 67

texana, Vaginulina___________________—________—_——_ 62, 67

thorensis, Cytheridea (Haplocythereldea) _____________—___ 74

toMana, Cytheropteron-___———-——_—————————-————— 85 

Pterygocythere_______________________ 63, 64, 69, 85, 86, pi. 9.

Trachyleberis _____________________________—______ 84

exanthemata _____________________—_________ 83

stenzeli- _—_—————_——————————————————————— 83 

triangularis, Asciocythere____—_———_—_————— 64, 69, 77, pi. 8 

trinitiensis, Cytheridea.____—___——_ —————— _———————— 86

Cytheropteron (Eocytheropteron) ______—___— 64, 69, 86, pi. 9

Trinity formation_________________ 59, 60, 61, 64, 65, 66, 67, 68 

triplicata, Protocythere___________________—____-_ 85

tumida Ilyocypris________________________ 64, 69, 70, pi. 8

tumidosa, Apatocythere_________________________ 65, 67, 69, 73, pi. 9

tumidum, Cytheropteron (Eocytheropteron) ____________ 60, 64, 86

tumoides, Cytheropteron (Eocytheropteron)-______—— 64, 69, 86, pi. 9

Tuscaloosa formation_____________________ 59, .60, 61, 63, 67

D

umbonata, MonoceratinaSchuleridea ____—,

88

72,74

Vaginulina regina___________________________ 62, 67

texana ________________________________ 62, 67

ventrosa, Metacypris___________—_________———_ 71 

virginea, Cytheropteron concentricum_—______—_______ 70

W

Washita formation_________________________ 59, 60, 61, 64 

Wells, location_______________________________ 60 

worthensis, Cythereis__________________—_——___—_ 83, 84

PLATES
PLATE 8

FIGURE 1. Cytherella navarroensis Alexander. Left side of a complete shell, X 37. Hatteras Light well no. 1, 3,240-3,250 feet, 

Black Creek(?) formation. U.S.N.M. 106906. (p. 68)

2. Cytherella cf. C. obesa Alexander. Left side of a complete shell, X 37. Hatteras Light well no. 1, 3,130-3,140 feet, 

Peedee(?) formation. U.S.N.M. 106907. (p. 68)

3. Cytherelloidea darensis Swain, n. sp. Left side of holotype, X 37. Hatteras Light well no 1, 7,500-7,510 feet, beds of 

Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106908. (p. 68)

4. Cyprisf sp. Exterior of a left valve, surface of which bears fine concentric striations, X 37. Hatteras Light well no. 1,

6,460-6,470 feet, beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106909. (p. 70) 

5, 6. Ilyocypris? tumida Swain, n. sp. Right side and dorsal views of holotype, X 37. Hatteras Light well no. 1, 6,350- 

6,360 feet, beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106910. (p. 70)

7. Paracypris sp. Right side of a complete specimen, X 38. Hatteras Light well no. 1, 6,700-6,710 feet, beds of Trinity(?)

and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106911. (p. 70)

8-12. Bairdopillata pondera Jennings. 8, Right valve view, X 38. Hatteras Light well no. 1, 4,640-4,650 feet, beds of Eagle 

Ford(?) age, U.S.N.M. 106912. 9, 12, Right valve views, X 37. Hatteras Light well no. 1, 3,780-3,790 feet, beds of 

Eutaw(?) age, U.S.N.M. 106913, 106915. 10, Ventral view, X 37. Hatteras Light well no. 1, 3,550-3,560 feet, beds of 

Eutaw(?) age or Black Creek (?) formation, specimen lost. 11, Right valve view of a specimen that is more strongly 

produced posteriorly than the other, X 37. Hatteras Light well no. 1, 3,410-3,420 feet, Black Creek (?) formation, 

U.S.N.M. 106914. (p. 71)

13. Bairdia? cf. B. alexandrina Blake. Right side of a complete example, X 37. Hatteras Light well no. 1, 4,750-4,760 

feet, beds of Eagle Ford(?) age. U.S.N.M. 106916. (p. 71)

14. Bairdiocypris? sp. Right side of a complete specimen, X 39. Hatteras Light well no. 1, 7,910-7,920 feet, beds of 

Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106917. (p. 72)

15. Haplocytheridea? sp. aff. H? plummeri (Alexander). Right side of a complete shell, X 37. Hatteras Light well no. 1,

3,990-4,000 feet, beds of Eutaw(?) age. U.S.N.M.106918. (p. 79)

16, 17. Haplocytheridea? graysonensis (Alexander). Right valve views of two examples, X 40. Hatteras Light well no. 1, core 

sample, 4,485-4,495 feet, beds of Eagle Ford(?) age. U.S.N.M.106919. (p. 78)

18. Haplocytheridea? berryi Swain, n. sp. Right side of holotype, X 37. Hatteras Light well no. 1, core sample, 3,380- 

3,390 feet, Black Creek(?) formation. U.S.N.M. 106920. (p. 78)

19. Haplocytheridea monmouthensis (Berry). Right side of a complete shell, X 35. North Carolina Esso well no. 2, 2,750- 

2,760 feet, beds of Eutaw(?) age or Black Creek(?) formation. U.S.N.M. 106921. (p. 79)

20. Asciocythere? acuminata Swain, n. sp. Right side of holotype, X 38. Hatteras Light well no. 1, 3,780-3,790 feet, beds 

of Eutaw(?) age. U.S.N.M. 106922. (p. 77)

21. Asciocythere macropunctata Swain, n. sp. Right side of holotype, X 37. Hatteras Light well no. 1, core sample, 3,693-

3,703 feet, beds of Eutaw(?> age. U.S.N.M. 106933. (p.77)

22-33. Asciocythere rotunda (Vanderpool), 22, 26, Right valve views of possible females, U.S.N.M. 106923, 106927; 27, left 

valve view of possible female, U.S.N.M. 106927; 29, right valve view of possible male, U.S.N.M. 106923; 32, ventral 

view of possible female, U.S.N.M. 106923; X 42, Hatteras Light well no. 1, 6,300-6,310 feet. 23, Right side of a 

possible female, X 42, Hatteras Light well no. 1, 7,330-7,340 feet, U.S.N.M. 106924. 24, Right side of a possible 

male, X 42, Hatteras Light well no. 1, 6,430-6,440 feet, U.S.N.M. 106930. 25, Interior of a left valve, X 42, showing 

anterior slightly denticulate elongate hinge socket, interterminal bar, and prominent mid-dorsal accommodation groove, 

Hatteras Light well no. 1, 6,420-6,430 feet, U.S.N.M. 106925. 28, 30, Right side and dorsal views of possible females, 

X 42, Hatteras Light well no. 1, 6,340-6,350 feet, U.S.N.M. 106931, 106928. 31, Ventral view of a possible female, 

X 42, Hatteras Light well no. 1, 7,450-7,460 feet, U.S.N.M. 106929. 33, Right side of a possible female, X 42, 

Hatteras Light well no. 1, 6,350-6,360 feet, U.S.N.M. 106926. All from beds of Trinity(?) and pre-Trinity(?) age, 

undifferentiated. (p. 76)

34. Asciocythere? triangularis Swain, n. sp. Right side of holotype, X 42. Hatteras Light well no. 1, 6,430-6,440 feet, beds 

of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106932. (p. 77)

35. Cytheridea washitaensis Alexander. Right side of a specimen from the Grayson formation of Texas, X 41, introduced as 

an example of a feytherideid typical of Washita group in Texas. Note lack of oblique sulcus postjacent to anterodorsal 

node, and compare with Schuleridea hatterasensis, n. sp., which may be a predecessor of the group of Cytheridea 

washitaensis. Specimen loaned through courtesy of C. I. Alexander.

36. Asciocythere? leguminoides Swain, n. sp. Right side of holotype, X 42. Hatteras Light well no. 1, 9,030-9,040 feet,

Upper Jurassic(?). U.S.N.M. 106934. (p. 78) 

37-39. Asciocythere? cf. A. amygdaloides (Cornuel). 37, Right side of an imperfectly preserved specimen, X 35, Hatteras Light

well no. 1, core sample, 6,132-6,137 feet, U.S.N.M. 106935. 38, Right side of a complete shell, X 35, Hatteras Light

well no. 1, 6,250-6,260 feet, U.S.N.M. 106936. 39, Right side of a partly exfoliated example that exhibits the muscle

scar, retouched, X 35, Hatteras Light well no. 1, 6,190-6,200 feet, U.S.N.M. 106937. All from beds of Trinity (?)

and pre-Trinity(?) age, undifferentiated. (p. 76) 

40, 41. Brachycythere darensis Swain, n. sp. Right side and dorsal views of holotype, X 40. Fatteras Light well no. 1, 3,200-

3,210 feet, Black Creek(?) formation. U.S.N.M. 106938, (p. 80) 

42, 43. Brachycythere sphenoides (Reuss). Left and right sides of two complete shells, X 37. Hatteras Light well no. 1, core

sample, 3,500-3,510 feet, Black Creek(?) formation. U.S.N.M. 106939. (p. 80) 

44-47. Brachycythere nausiformis Swain, n. sp. 44, 45, Right side and dorsal views of male cotype, X 38, Hatteras Light well

no. 1, 3,780-3,790 feet, beds of Eutaw(?) age, U.S.N.M. 106940. 46, Right side of a female cotype, X 38, North

Carolina Esso well no. 2, 2,750-2,760 feet, beds of Eutaw(?) age or Black Creek(?) formation, U.S.N.M. 106941.

47, Right side of a female cotype, X 38, Hatteras Light well no. 1, 3,640-3,650 feet, Black Creek(?) formation,

U.S.N.M. 106942. (p. 80)
GEOLOGICAL SURVEY PROFESSIONAL PAPER 234 PLATE 8

CYTHERELLIDAE, CYPRIDAE, BAIRDIIDAE AND CYTHERIDAE
GEOLOGICAL SURVEY PROFESSIONAL PAPER 234 PLATE 9

CYTHERIDAE

CONTENTS

Page 

Part 1, Cenozoic Ostracoda (Published in August 1952)_____________________________________-__-_-_------____---- 1

Part 2, Mesozoic Ostracoda (Published in June 1952)______.___________ ______________________--___-----_-----_---- 59

ILLUSTRATIONS

Page 

Plates 1-7. Cytherellidae, Cypridae, Bairdiidae, and Cytheridae.___„____________--_________-___-___----_-_----Follow 58

8. Cytherellidae, Cypridae, Bairdiidae, and Cytheridae__--____-----_-----__----_--_-----------------Follows 93

9. Cytheridae.-.____________..__________________________________.______Follows 93

Figure 1. Index map showing eastern North Carolina localities studied._._____-_-_-___________-__..------------------- 2

2. Stratigraphic relationships of Cenozoic rocks in Esso Standard Oil Co. Hatteras Light Well No. 1 and North Carolina Esso Well No. 2, Eastern Dare County, N. C____________-_________--_____--_____-_-____---___---- 5

3. Cytherellidae and Cytheridae______________.._-__.___._....___._____..___________-_-__________-_______-_ 15

4. Index map showing locations of wells___________.___.-____..__________.._._____--______-__--.---_-__-_----_ 60

5. Stratigraphic sections of the Upper Cretaceous rocks in Hatteras Light Well No. 1 and North Carolina Esso Well

No. 2__—-_..-_._.-._...___.___.__--_„___.-___.__.._._---._-__-____-_-_..____...______..--_._.---- 61

6. Stratigraphic sections of the Lower Cretaceous rocks in Hatteras Light Well No. 1 and North Carolina Esso Well

No. 2..__._____________________________________________________________.__-_.__________________ 61

7. Stratigraphic section of Upper Jurassic (?) and pre-Cambrian rocks in Hatteras Light Well No. l_.____---_______ 62
UNITED STATES DEPARTMENT OF THE INTERIOR 

Oscar L. Chapman, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office

Washington 25, D. C.
Ostracoda From Wells 

in North Carolina

By FREDERICK M. SWAIN

GEOLOGICAL SURVEY PROFESSIONAL PAPER 234

Part I, Ceno%oic Ostracoda 

Part 2, Mesozoic Ostracoda

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1952

PLATE 9

FIGURE 1-3. Pterygocythereis cf. P. tokiana (Israelsky). 1,2, Left side and ventral views of a complete shell, X 37. Hatteras Light 

well no. 1, 6,310-6,320 feet, beds of Trinity (?) and pre-Trinity(?) age, undifferentiated; U.S.N.M. 106943, possibly 

represents a specimen caved from a higher level. 3, Exterior of a crushed left valve, X 37. Hatteras Light well no. 

1, 4,440-4,450 feet, beds of Eagle Ford(?) age, U.S.N.M. 106944. (p. 85)

4. Cythereis? pamlicoensis Swain, n. sp. Right side of holotype, X 36. North Carolina Esso well no. 2, 2,310-2,320 feet, 

Peedee(?) formation. U.S.N.M. 106945. (p. 82)

5. Cythereis sp. aff. C. rugosissima Alexander. Right side of a complete shell, X 37. Hatteras Light well no. 1, 4,600- 

4,610 feet, beds of Eagle Ford(?) age. U.S.N.M. 106946. (p. 81)

6. Cylhereis sp. aff. C. fredericksburgensis Alexander. Right side of a specimen made elongate by compaction, X 37. 

Hatteras Light well no. 1, 7,310-7,320 feet, beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 

106947. (p. 82)

7. 8. Cytheropteron (Eocytheropterori) iumoides Swain, n. sp. 7, Right side of holotype, X 38, Hatteras Light well no. 1, 

6,760-6,770 feet, U.S.N.M. 106948. 8, Dorsal view of a paratype, X 38, Hatteras Light well no. 1, 6,340-6,350 feet, 

beds of Trinity(?) and pre-Trinity(?) age, undifferentiated, U.S.N.M. 106949. (p. 86)

9, 10. Cytheropteron (Eocytheropterori) Triniiiensis (Vanderpool). Left side and dorsal views of a complete shell, X 38. 

Hatteras Light well no. 1, 6,340-6,350 feet, beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 

106950. (p. 86) 

11. Krithe cf. K. postprojecla Schmidt. Right side of a complete shell, X 38. North Carolina Esso well no. 2, 2,300-2,310

feet, Peedee(?) formation. U.S.N.M. 106951. (p. 87)

12, 13. Monoceratina sp. aff. M. semiornata Alexander. Right side and dorsal views of a specimen that is imperfect post-midventrally, X 38. Hatteras Light well no. 1, 3,800-3,810 feet, beds of Eutaw(?) age. U.S.N.M. 106952. (p. 88)

14. Hutsoniaf microrugosa Swain, n. sp. Left side of holotype, X 38. Hatteras Light well no. 1, 6,260-6,270 feet, beds

of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106953. (p. 88) 

15, 16. Cytheropteron (Eocytheropterori) acaudatum Swain, n. sp. Right side and ventral views of holotype, X 38. Hatteras

Light well no. 1, 5,640-5,650 feet, beds of Washita(?) age. U.S.N.M. 106954. (p. 87) 

17. Macrodenlina? obliqua Swain, n. sp. Right side of holotype, X 35. Hatteras Light well no. 1, 8,330-8,340 feet, beds

of Trinity(?) and pre-Trinity(?) age, undifferentiated" U.S.N.M. 106955. (p. 89)

18-21. Prolocythere paratripticata Swain, n. sp. 18, 19, Right side and dorsal views of holotype, X 38, Hatteras Light well no. 

1, 3,240-3,250 feet, Black Creek(?) formation, U.S.N.M. 106956. 20, 21, Right side and dorsal views of paratype, 

X 38, Hatteras Light well no. 1, 4,840-4,850 feet, Tuscaloosa(?) formation, U.S.N.M. 106957. (p. 85)

22. Brachycythere arachoides (Berry). Right side of a complete shell, X 37. North Carolina Esso well no. 2, 2,310-2,320 

feet, Peedee(?) formation. U.S.N.M. 106958. (p. 81)

23. Gomphocytheref cf. G. silvana Martin. Right side of a complete shell, X 37. Hatteras Light well no. 1, 8,430-8,440 

feet, beds of Trinity(?) age and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106959. (p. 87)

24-26. Cythereis ornatissima (Reuss). 24, 25, Right side and ventral views of a complete shell, X 38, Hatteras Light well no. 1, 

4,410-4,420 feet, beds of Eagle Ford(?) age, U.S.N.M. 106960. 26, Right side of a shell having slightly longer spines, 

and a more strongly elevated anterior cardinal angle, X 38, Hatteras Light well no. 1, 4,640-4,650 feet, beds of Eagle 

Ford(?) age, U.S.N.M. 106961. (p. 84)

27-30. Cythereis quadrialira Swain, n. sp. 27, 28, Right side and dorsal views of a somewhat abraded paratype, X 37, Hatteras 

Light well no. 1, 3,750-3,760 feet, Eutaw formation, U.S.N.M. 106962. 29, 30, Right side and dorsal views of 

holotype, X 37, North Carolina Esso well no. 2, 2,750-2,760 feet, beds of Eutaw(?) age or Black Creek(?) formation 

U.S.N.M. 106963. (p. 84)

31. Cythereis bicornis Israelsky. Exterior of a left valve, X 36. Hatteras Light well no. 1, 4,320-4,330 feet, beds of Eagle 

Ford(?) age, U.S.N.M/106964. (p. 83)

32-34. Cythereis simulonuda Swain, n. sp. 32, 33, Right side and ventral views of holotype, X 38, Hatteras Light well no. 1, 

5,340-5,350 feet, Tuscaloosa(?) formation, U.S.N.M. 106965. 34, Right side of a paratype, X 38, Hatteras Light 

well no. 1, 4,780-4,790 feet, beds of Eagle Ford(?) age, U.S.N.M. 106966. (p. 83)

35-38. Schuleridea hatterasensis Swain, n. sp. 35, Right side of holotype, X 40, Hatteras Light well no. 1, 6,477-6,482 feet, 

U.S.N.M. 106967. 36, 37, 38, Right sides of three paratypes, X 37, Hatteras Light well no. 1, from depths of 

7,430-7,440 feet, 6,480-6,490 feet, and 6,380-6,390 feet, respectively, U.S.N.M. 106968-106970. All from beds 

of Trinity(?) and pre-Trinity(?) age, undifferentiated. (p. 74)

39,41,42,46. Apatocythere? lanceolata Swain, n. sp. 39, Right side of holotype, a specimen that is slightly imperfect anteroventrally, 

X 37, Hatteras Light well no. 1, 7,250-7-,260 feet, U.S.N.M. 106971. 41, Right side of a paratype, imperfect 

terminally, X 37, Hatteras Light well no. 1, 7,310-7,320 feet, U.S.N.M. 106972. 42, Left side of a paratype 

shell, imperfect dorsally, X 37, Hatteras Light well no. 1, 7,560-7,570 feet, U.S.N.M. 106973. 46, Right side of a 

paratype, X 37, Hatteras Light well no. 1, 6,930-6,940 feet, U.S.N.M. 106974. All from beds of Trinity(?) and 

pre-Trinity(?) age, undifferentiated. (p. 72)

40, 43, 45. Apatocythere? leguminoidea Swain, n. sp. 40, Right side of a paratype, X 37, North Carolina Esso well no. 2, 5,560- 

5,570feet, U.S.N.M. 106975. 43, 45, Right side and dorsal views of holotype, X 37, Hatteras Light well no. 1, 

6,350-6,360 feet, U.S.N.M. 106976. Both from beds of Trinity (?) and pro-Trinity (?) age, undifferentiated. 

(p. 73)

44. Apatocythere? tumidosa Swain, n. sp. Right side of holotype, X 33. Hatteras Light well no. 1, 8,300-8,310 feet, 

beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106977. (p. 73)

47. Schuleridea cf. S. acuminata Swartz and Swain. Right side of a complete shell, in which the surface is poorly preserved, 

X 40. Hatteras Light well no. 1, 9,100-9,110 feet, Upper Jurassic(?). U.S.N.M. 106978. (p. 75)

48. Schuleridea? lacustris Swain, n. sp. Right side of holotype, X 35. North Carolina Esso well no 2, 4,970-4,980 feet, 

beds of Trinity(?) and pre-Trinity(?) age, undifferentiated. U.S.N.M. 106979. (p. 74)

49. Schuleridea cf. S. pentagonalis Swartz and Swain. Right side of a somewhat imperfect specimen, X 41. Hatteras 

Light well no. 1, core sample, 9,115-9,116 feet, Upper Jurassic(?). U.S.N.M. 106980. (p. 75)