Ostracodes from the 

Upper part of the 

Sundance Formation of 

South Dakota, Wyomin 

and Southern Montana

GEOLOGICAL SURVEY PROFESSIONAL PAPER 243-A
Ostracodes from the 

Upper part of the 

Sundance Formation of 

South Dakota,Wyoming 

and Southern Montana

By FREDERICK M. SWAIN and JAMES A. PETERSON

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952, PAGES 1-18

GEOLOGICAL SURVEY PROFESSIONAL PAPER 243-A

Description and illustrations of a 

Late Jurassic fauna from the Redwater 

shale member', distribution of ostracodes in the Swift formation

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 35 cents
CONTENTS

Abstract..._ __________________________________

Introduction ___________________________________

Stratigraphic sections._____-_---_-____________-

Ancestral relationships of the Redwater ostracodes. 

Description of species__________________________

Cy therelh'dae_ ___________________________

Page 

1

1

2

7

Description of species—Continued 

Cypridae ___________________

Cytheridae__ _ -_____-_______-

References- _____________________

Index._.____-___________-__-__.

Page

9

10

14

17

ILLUSTRATIONS

Pag*

Plate 1. Cytherellidae, Cypridae, and Cytheridae._________-_______________---___-_-------_-----_---following index

2. Cytheridae._____________•_____________________________________________________________.following index

Figure 1. Index map showing localities from which the ostracodes described or listed in this paper were obtained.__________ 2

in

OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION OF SOUTH 

DAKOTA, WYOMING, AND SOUTHERN MONTANA

By FREDERICK M. SWAIN and JAMES A. PETERSON

ABSTRACT

The Redwater shale member of the Sundance formation or 

the upper part of the Sundance of Late Jurassic age in South 

Dakota, Wyoming and Montana has yielded 16 species of Ostracoda representing: Paraparchites Ulrich and Bassler, Eridoconcha 

Ulrich and Bassler, Cytherella Jones, Macrocypris Brady, Aparchitocythere Swain and Peterson, n. gen., Monoceratina Roth, 

Camptocythere Triebel, Leptocythere Sars, Cytherura Sars, Progonocy'there Sylvester-Bradley, Protocythere Triebel, Cythereis 

Jones. These species are described and illustrated.

Aparchitocythere n. gen., may have descended from Ellipsella 

Coryell and Rogatz of the Carboniferous and Permian or from 

a related genus, which in turn may have descended from Graphiodactylus Roth of the Devonian and Mississippian.

The Jurassic species of Monoceratina Roth, Leptocythere Sars, 

Cytherura Sars, and Camptocythere Triebel resemble Aparchitocythere in several features of the shell but Monoceratina at least 

seems to have originated in the Devonian from some genus other 

than Graphiodactylus. The Jurassic genus Progonocythere Sylvester-Bradley may lie in the evolutionary stock that contains 

Savagella lindahli (Ulrich) of the Mississippian. Protocythere 

Triebel of the Jurassic and Cretaceous may have descended from 

some species of Basslerella Kellett of the Carboniferous and 

Permian.

A new species here referred to Cythereis Jones may bear an 

ancestral relationship to Amphissites Girty or to a middle and 

late Paleozoic kirkbyid.

INTRODUCTION

This paper is the second dealing with marine Jurassic 

ostracodes from the western interior United States. 

The first article described species that occur in the 

Eedwater shale member of the Sundance formation at 

the type locality (no. 1 on fig. 1) on Redwater Creek, 

south half, Sec. 2, T. 7 N., E. 1 E., Butte County, 

South Dakota (Swain and Peterson, 1951).

The present article deals with ostracodes obtained by 

Imlay and Loeblich from the Kedwater shale member 

of the Sundance formation at other localities in South 

Dakota, Wyoming and southern Montana, and also 

lists ostracodes from the stratigraphically equivalent 

Swift formation of central Montana. Imlay (1947, p. 

231, 1949, p. 79) correlated the Redwater shale member, 

which is the upper part of the Sundance, with the Oxfordian stage of Europe. A more complete study of the

stratigraphic distribution of the ostracodes of the Redwater in wells in the Powder River Basin, eastern 

Wyoming, is being conducted by J. A. Peterson.

It is hoped later to describe the ostracodes collected 

by Imlay and Loeblich from the lower part of the Sundance formation of South Dakota, Wyoming and southern Montana and from the equivalent Rierdon formation of central Montana. In addition, papers on the 

Foraminifera are being prepared by A. R. Loeblich, 

Jr., and Helen Tappan (Mrs. A. R. Loeblich) (1950a, 

1950b).

The Redwater shale member has yielded 16 species of 

Ostracoda, 14 of them new, representing 12 genera, one 

of which is new. Two genera are recorded for the first 

time in North America. The following species were 

obtained at the type locality of the Redwater shale 

member (Swain and Peterson, 1951): Paraparchites? 

sp., Eridoconcha monopleura Swain and Peterson, 

Aparchitocythere loeblichorum (Swain and Peterson), 

Progonocythere hieroglyphica Swain and Peterson, P. 

crowcreekensis Swain and Peterson, Cytherura lanceolata 

Swain and Peterson, Monoceratina sundancensis Swain 

and Peterson, Leptocythere imiayi Swain and Peterson, 

and Cytheridea? sp.

The doubtful Paraparchites and the Eridoconcha, as 

representatives of the Leperditellidae (a family which 

almost completely died out at the end of the Paleozoic 

era), form the most primitive elements of the Redwater fauna. They have not been found in the collections from other localities in the Redwater member or 

in the underlying portions of the Sundance. The 

Cytherellidae are represented in the Redwater by two 

species and the Cypridae by one species. The other 

ostracodes from the type locality are Cytheridae, 

mostly of primitive character with the terminal hingeteeth and sockets weak or crenulate.

The following species were not found in the type 

locality of the Redwater shale member and are described here: Cytherella paramuensteri, C. ventropleura, 

Macrocypris minutus, Aparchitocythere typica, Cythereis? 

zygoventralis, Protocythere quadricarinata, and Camptocythere elliptica.
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

—— __ __ — C A N ADA __ __ __ —— ,-- —— —— _ __ —— _________ - - ^

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LIST OF LOCALITIES

1. Redwoter shale, SI/2 sec. 2,T. 7N..R.I E.,Butte

County , S. Dak.

Sheridan County, Wyo. 

3. Redwoter shale, sec. I8,T. 45N..R.60W.

Weston County, Wyo.

4. Redwater shale, sec. 3,T. 6 N., R. 2 E .,

Lawrence County, S. Dok.

5. Redwoter shole , N 1/2 sec. 14 , T. 7 S., R.3 E

Foil River County, S. Dak. ' '

6. Swift formation, sec. 19, T. 7 S., R. 24 E .,

Carbon County, Mont.

7. Swift formation, sec. 2, T. 14 N. , R. 19 E and 

sec. 35., T. 15 N., R. 19 E., Fergus County, Mant. 

8. Swift formation, sec.- 17, T. 14 N., R.20E.,

Fergus County, Mont.

9. Swift formotion, sec. 32, T. 25 N R 24 E

Phillips County, Mont.

10. Swift formation , sec. 36, T. 53 N., R. 102 W. 

Park County, Wya. '

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FIGURE 1.—Index map showing localities from which the ostracodes described or listed were obtained.

In the present material, ostracodes were most abundant in Red Gulch, Sheridan County, Wyoming. 

Descriptions of this and the other measured sections of 

the Redwater shale member from which ostracodes 

were obtained follow. Index numbers assigned to beds 

that were sampled (J-61p, etc.) indicate the occurrence 

of each species in the Descriptions of Species.

STRATIGRAPHIC SECTIONS

The following sections were measured and described 

by R. W. Imlay in 1945, and samples were collected for 

microfossils by R. W. Imlay and A. R. Loeblich in 1948:

Jurassic formations along east side of Red Gulch about 2% 

miles south of Little Horn River in Sec. 22, T. 58 N., R. 89 W., 

Sheridan County, Wyoming. (Measured by R. W. Imlay and 

Wm. Saalfrank 1945.) Collected September 23, 1948 by R. W. 

Imlay and A. R. Loeblich, Jr. (Locality 2 on fig. 1.)

Kootenai formation (basal part):

Sandstone, fine-grained, grayish-white_____________

Concealed. ____________________________________

Sandstone, massive, cliff-fonning, light-gray, strongly 

cross-bedded, irregular lower surface.___________

Morrison formation:

64. Shale, soft, light-red, upper 3 feet mostly greenish-gray———— —————— ————————.___ 

63. Sandstone, hard, light-gray, weathers yellowish. 

62. Shale and some sandstone, yellowish-gray______

61. Shale, soft, yello wish-gray. _ ___________ _______

60. Sandstone, hard, grayish-white, weathers dark 

gray, forms ledge__________________

59. Shale, soft, light greenish-gray._______________

58. Sandstone, hard, grayish-white, weathers dark 

gray, forms ledge________________________

57. Shale, partly silty, light-red and greenish-gray. _ _ 

56. Limestone, shaly, hard___________________

55. Shale, light-red, becoming yellowish at top___._ 

54. Sandstone, fairly hard, light-gray___________

Feet

4

15

20

15

IK 

4 

6

3

25

4

24

1

7
OSTRACODES FROM THE UPPER PART OF THE STJNDANCE FORMATION

Morrison formation—Continued

53. Shale, yellow to gray, silty, several thin layers of 

fine-grained gray sandstone near top_________

52. Shale, ribboned dark- and light-gray, silty_ _____

Feet

3J.

8

Total thickness of the Morrison formation 102>_

Sundance formation: 

Part of the Redwater shale member:

51. Sandstone, light-yellow, soft, cross-bedded, forms 

cliff locally, upper part massive, lower part 

thin- to medium-bedded__________________ 23

50. Shale, sandy, thinly ribboned with gray shale,

light-yellow, soft__________________________ 5

49. Sandstone, hard, light-yellow, cross-bedded. ____ 1

48. Sandstone and shale, thinly bedded, soft_______ 1

47. Sandstone, massive, very soft, dark-yellow, some

glauconite. _______________________________ 2

46, Sandstone, hard, light yellowish-gray._____ %to 1%

45. Sandstone, massive, very soft, dark-yellow, some

glauconite_ ——————— ____________ 7

44. Shale, sandy, yellowish-gray, soft, mostly covered.—_.____________________ 25

43. Sandstone, shaly, yellow_____________________ 3

42. Shale, sandy, dark yellowish-gray.____________ 20

41. Limestone, silty, nodular_____________________ %

40. Shale, sandy, medium-gray___________________ 7

39. Shale, calcareous, medium-gray, abundant

belemnites and Gryphaea nebrascensis ________ 138

Total thickness of the Redwater shale 

member. ___________________________ 233

Channel samples of Redwater shale Height above 

member: base (feet) 

J-61p_________________________ 145-152

o._---__-_---___________ 137-145

n_._______________________ 130-137

m________________________. 122-130

L._ —_____________________ 117-122

k_________________________ 112-117

j__________________________ 107-112

L____ —___________________ 102-107

h_________________________ 97-102

g__-______________________ 92- 97

f__________________________ 86- 92

e_________________________ 80- 86

d_________________________ 68- 80

c__. ______________________ 58- 68

b__---_____._-____________ 48- 58

a__---____________________ 11- 21

Hulett sandstone member:

38. Oolite, fine, sandy, light-brown, weathers yellowish brown, traces of fossils_.________________ 6

37. Sandstone, massive, hard, forms top of cliff, light 

yellowish-gray, fine-grained, cross-bedded, 

weathers light gray________________________ 10

36. Oolite, coarse, yellowish-gray, weathers light

gray, upper 6 inches soft and fossiliferous. _ _ - \% 

35. Sandstone, chunky, grayish-white, weathers

whitish_ _________________________________ 3

34. Sandstone, calcareous, massive, light yellowishgray, weathers buff, fine grained ____________ 7

33. Oolite, silty, gray..__. — __ — ____________ 1

Total thickness of Hulett sandstone

member. ___________________________ 28>_

Sundance formation—Continued Feet 

Stockade Beaver shale member:

32. Shale, soft, brownish-gray, papery, fine, sandy,

forms base of cliff_________________________ 5

31. Shale, soft, brownish-gray, papery fine, sandy_ 15 

30. Shale, soft, calcareous, medium-gray, abundant

Gryphaea nebrascensis, some belemnites- _____ 76 

29. Shale, calcareous, gray, contains several beds of

slightly oolitic gray limestone, fossiliferous-_ _ 5}_ 

28. Shale, calcareous, gray. Sample J-60a from beds

28 and 29---___-_-_-___________________ 1Y2

Total thickness of Stockade Beaver shale. _ 103 

Channel samples of Redwater shale member:

Height above 

base (feet)

J-60m__._-______________________ 68-76

!-___________________________ 60-68

k___________________________ 52-57

]•____________________ —______ 47-52

i__________________________ 42-47

h____-____--__--___-____--._ 37-42

g___________________________ 32-37

f._______-______-___-_--.____ 27-32

e-__________________________ 22-27

d___________________________ 17-22

c_-------------------------- 12-17

_>_-___-___-_-__--___-_-_-___ 7-12

Gypsum Spring formation:

27. Shale, maroon, soft__________________________ 41

26. Shale, light greenish-gray___________________ 5

25. Limestone, silty, white, soft, some thin beds of 

yellowish chert, upper foot weathers yellow, 

remainder weathers white_________________ 6

24. Shale, soft, light-red, some white layers in lower 

half, become light pink toward top, uppermost 

foot purplish__.--___.______-__-_-__-____ 23

23. Clay-shale, soft, white__________________-____ 6

22. Limestone, shaly, greenish-gray _______________ ^_ to 2

21. Shale, fairly soft, mostly purplish-pink; many

layers are greenish-gray____________________ 4

20. Limestone, shaly at base and top, hard and ledgeforming in middle; mainly light gray with some 

pinkish layers, grades into underlying unit, 

fragmentary pelecypods at top______________ 3%

19. Shale, soft, mostly maroon, some greenish-gray _ 13 

18. Shale,soft,greenish-gray,somepink____________ 12

17. Limestone, dolomitic, hard, dense, light-gray,

leached __________________________________ £_

16. Shale, light-red to greenish-gray, soft___________ )_

15. Limestone, dolomitic, hard, dense, light-gray—__ 1 

14. Limestone, oolitic, light-yellow._______________ %

13. Shale, soft, light-red.___._.__________ %

12. Limestone, dolomitic, hard, dense, light-gray____ 1J>_

11. Shale, chunky, soft, pink to yellow, partly silty _ 2}_ 

10. Limestone, thin-bedded, white, dense._________ 1

9. Shale, soft, pink to light-green ________________ >_

8. Limestone, light yellowish-gray, dense, hard,

laminated._-_______-_-_____-____---__--__ 1

7. Shale, soft, pink to gray, one 3-inch layer of dense

white limestone in middle. _________________ 5

6. Limestone, dense, hard, nearly white __________ ItolJ^

5. Shale, deep-red, soft, spotted with gray-_______ 1

4. Shale, light greenish-gray, soft, some layers

nodular_ __________-_-______--_-_-----.--__ 5
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

Feet

Gypsum Spring formation—Continued Feet 

3. Shale, partly silty, maroon, traces of greenish

shale--____________________.___ 10

2. Siltstone and silty shale, maroon, some spots of

light green throughout _____________________ 40

1. Siltstone, maroon, weathers pinkish, rests on

leached to slightly cavernous maroon siltstone

of Chugwater formation____________________ 8

Total thickness of Gypsum Spring formation. ______________________________ 195J4

Chugwater formation

The Red Gulch locality yielded most of the ostracodes 

described herein. A table showing distribution of the 

species in the Redwater shale member of the Sundance 

formation at Red Gulch faces p. 6.

Gypsum Spring and Sundance formations on west side of 

Stockade Beaver Creek, 5 miles NE of Newcastle in Sec. 18, 

T. 45 N., R. 60 W., Weston County, Wyoming. (Locality 3 on 

fig. 1.) Collected Sept. 21, 1948 by R. W. Imlay and A. R. 

Loeblich, Jr.

Sundance formation (part): 

Redwater shale member (part):

12. Shale, gray and greenish-gray; some layers are 

silty to sandy; contains many belemnites and 

some selenite; top not exposed.

11. Sandstone, yellowish-gray, very soft, fine-grained. 5 

10. Shale, gray, partly silty, soft_________________ 18

9. Sandstone, white; weathers light gray, fairly 

soft, thick to thin-bedded, glauconitic; includes 

some thin beds of gray shale and shaly sandstone ____________________________________ 7

Channel samples of Redwater shale member:

Height above 

base (feet)

J-52f_ —_-- — _ — -___-___--_--___ 81-88 

e__-___________________.--__ 74-81

d_--__---.__-_-_--__-_______ 33-41

c________ ___________________ 28-33

b---__--__--__---_-___._____ 7-25

Lak member:

8. Siltstone and sandstone, mostly maroon; a 2-foot 

bed of greenish gray siltstone 15 feet below 

top in a sharp contact with overlying glauconitic sandstone____________________________ 80

lulett sandstone member:

7. Sandstone, white, massive, soft, very fine grained; 

grades upward into siltstone and then into a 

foot of soft green shale at top_____________ 6

6. Siltstone, shale and some fine-grained sandstone, 

greenish gray to yellowish gray, weathering 

pink to buff___,__________________________ 9

5. Sandstone, thick-bedded; forms sheer cliff; 

ripple-marked, light grayish yellow, weathering buff, glauconitic_______________________ 30

4. Shale, sandy, imterbedded with shaly to thinbedded sandstone; shale is greenish gray; sandstone is yellow; grades into adjoining units; 

forms recess in cliffs;'contains Camptonectes_ 12 

3. Sandstone, medium- to thick-bedded with some 

shaly partings, ripple-marked, light grayish 

yellow, weathering buff, glauconitic; grades 

into underlying unit_______________________ 12

Sundance formation—Continued Feet 

Stockade Beaver shale member:

2. Shale, dark gray, soft, fissile; contains some 

nodules of limestone in lower 10 feet and some 

limonitic shaly sandstone in lower foot; selenite 

crystals and Camptonectes present ___________ 63

Channel samples of Stockade Beaver shale 

member:

Height above 

base (feet)

J-51J — ___-__-__-_-_-_---------- 55-63

i_______ _______-.-_--------_ 50-55

h_._________________-_--__-- 45-50

g___________________________ 39-45

f________________-__---_----- 34-39

e___________________________ 27-34

<_--__---__-- — — — - — - — _ 22-27 

c_-_______-____------_------ 16-22

b------__-_-_-_ —-_ — — --— 8-16

a__________-___-__---_--___- 0-8

Gypsum Spring formation:

1. Gypsum, white, granular, bedded; forms low 

cliff; rests sharply on the slightly irregular 

surface of the red beds of the Spearfish formation. ________________________________ 8-12

Spearfish formation:

Sundance and Gypsum Spring formations one mile northnortheast of center of Spearfish in Sec. 3, T. 6 N., R. 2 E.> 

Lawrence County, South Dakota. Collected September 21, 1948 

by R. W. Imlay and A. R, Loeblich, Jr. (Locality 4 on fig. 1.) 

Morrison formation:

Mostly covered. Basal beds consist of fine-grained, pseudooolitic, yellow sandstone. 

Sundance formation:

Redwater shale member: Feet 

18. Shale, dark-gray fissile; contains some very thin

beds of fine-grained, greenish-gray sandstone. 15 

17. Limestone, shaly, and sandy shale, fossiliferous. 8 

16. Shale, dark-gray; some silty beds in lower 25 feet;

belemnites abundant_____________________ 65

15. Sandstone, yellow, soft________________•_____ 2

14. Shale, dark-gray----_-_----_---_--_--------- 11

13. Sandstone, yellow, soft_____________________ 2

12. Shale, greenish-gray, silty_________----___-___ 7

11. Sandstone, gray, soft, glauconitic____________ %

Channel samples of Redwater shale

member:

Height above 

base (feet)

J-47h__________________________ 95-106

g_--_____--_--_-__.-__---__ 85-95

f__.___-_______-___-__--_-_- 77-85

e_ _____________-____-_--_..- 69-77

d_-____--_-____-_____--_-_- 59-69

c._________________________ 49-59

b_______ —- — __ — _- — — _— 21

a______________-_____.-____ 1-8

Lak member:

10. Sandstone, fine-grained, and siltstone, mostly 

maroon; some greenish layers and spots; 

weathers light pink____-___________________ 60

Hutett sandstone member:

9. Sandstone and silty shale, soft, yellowish-gray __ 17+ 

8. Shale, silty, greenish gray.___________________ 6

7. Sandstone, fine-grained, mostly yellow, some

pinkish._________________________________ 4
OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION

Sundance formation—Continued Feet 

Hulett sandstone member—Continued

6. Shale, silty, and siltstone, light red and yellowish, weathering pinkish____________________ 11

5. Shale, sandy, greenish gray to pinkish; some

pink shaly sandstone ______________________ 12

4. Sandstone, thick- to medium-bedded, mostly 

pink to yellow, fine-grained, ripple-marked, 

glauconitic_ ______________________________ 6

3. Shale, greenish-gray, partly sandy, poorly exposed. ___________________________________ 12

2. Sandstone, thick- to medium-bedded, mostly 

pink to yellow, fine-grained, ripple-marked, 

gla ucom'tic _______________________________ 29

Stockade Beaver shale member:

1. Shale, soft, brownish gray in lower 15 feet, dark 

gray above; weathers yellowish gray; a few 

pitted pebbles of a very dense metamorphic 

rock in basal foot.________________________ 60

Channel samples of Stockade Beaver

shale member:

Height above 

base (feet)

J-46h___________________________ 55-60

g___________________________ 45-53

f__.___________ _____________ 38-45

e___________________________ 30-38

d_-_._______________________ 23-30

c_ __________________________ 14-23

b___ _________________ 6-14

a___________________________ 0-6

Samples from Stockade Beaver member are channel

samples. 

Gypsum Spring formation (part):

Gypsum, bedded, white, sugary___________________ 1

Shale, yellowish-gray, soft. Sample J-45__________ 2

Sundance formation about three miles west-northwest of 

Minnekahta in the N}_ Sec. 14, T. 7 S., R. 3 E., Fall River 

County, South Dakota. Collected September 22, 1948 by R. 

W. Imlay and A. R. Loeblich, Jr. (Locality 5 on fig. 1.) 

Sundance formation:

Redwater shale member: Peet 

15. Shale, dark-gray, soft, fissile; upper part has 

many ledges of limestone from a few inches to 2 

feet thick, belemnites common near base. 

Overlain, apparently along a fault contact, by 

about 15 feet of fossiliferous gray limestone 

that grades up into hard fine-grained white 

sandstone that is overlain by shale typical 

of the Morrison formation. Estimated thickness of the shale__________________________ 80

14. Sandstone, shaly, light gray, glauconitic, ripplemarked, poorly exposed.___________________ 18

13. Sandstone, greenish gray, soft, glauconitic ______ 9

Height above

Incomplete thickness of Redwater shale 

member_ ___________________________

Channel samples of

Redwrater shale member:

J-56c_________________________ 18-23

d___________________________ 23-30

b.__________________________ 13}.

107

Sundance formation—Continued 

Lak member:

12. Shale, maroon, soft_____________

11. Sandstone, maroon, massive _____

10. Shale, grayish-green.___________

9. Siltstone and shale, maroon_____

8. Sandstone, salmon-pink, massive, 

7. Siltstone and shale, maroon____

Total thickness of Lak member. ________

Hulett sandstone member:

6. Shale, medium gray to greenish gray___________

5. Sandstone, nearly white, medium-bedded at base, 

shaly in middle, and thin-bedded at top, 

medium- to fine-grained, ripple-marked, 

weathers light gray_______________________

Feet

18

4

5

6

12

15

60

10

22

Total thickness of Hulett sandstone member______________________________ 32

Sample J-55 is from zone 6, 22 to 32 feet above

base of Hulett sandstone member. 

Stockade Beaver shale member:

4. Shale, dark gray, some limonitic nodules and very 

thin layers of calcareous sandstone in lower 5 

feet. Lower foot characterized by fossiliferous 

limonitic nodules and by subangular pebbles 

from }i to % inch in diameter of a very hard, 

dense metamorphic rock. U.S.G.S. Mes. Loc. 

19558 from basal 5-foot zone contains Eumicrotis curia (Hall), Corbicellopsis? inornata 

(Meek and Hayden), Quenstedtia sublewis 

(Meek and Hayden), and Adtartef fragilis 

Meek and Hayden. U.S.G.S. Mes. Loc. 19559 

collected from the entire unit contains Pentacrinus asteriscus Meek and Hayden, Eumicrotis 

orbiculata (Whitfield), E. curta (Hall), Camptonnectes extenuatus (Meek and Hayden), Pleuromya subelliptica (Meek and Hayden), Corbicellopsisl inornata (Meek and Hayden), Ostrea 

sp., and Pachyteuthis sp__________---____-_- 48

Channel samples of Stock- Height above 

ade Beaver shale member: base (feet) 

J-54g___—__-_ — -- — — -- — — — 35-41 

f____________._______________ 31-35

e___ —__-_---__-----__-_--_- 25-31

d_ _______________________ 17-25

c—_________________________ 11-17

b___________________________ 6-11

a____________________________ 0- 6

Gypsum Spring formation:

3. Sandstone, white, medium-bedded, mediumgrained, grades into underlying beds________ 2%

2. Sandstone, red to salmon-pink, massive, cliffforming but fairly soft, coarsely cross-bedded, 

moderate- to fine-grained, some fine chert grit 

throughout, weathers brick red; 1 foot of white 

sandstone about 2 feet below top____________ 42

1. Sandstone in two massive beds; lower bed pink 

to yellow; upper bed yellow; rather soft, contains chert grit and some pebbles as much as 

}_ inch in diameter_______________________ 3

Total thickness of Gypsum Spring formation__________________________

993981—52-
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

Distribution of Ostracoda in the Redwater shale member of the Sundance formation, Red Gulch section^ Sheridan County, Wyo.

[Locality 2 on fig. 1, samples l-61a-p.]

steri, n. sp.

ra, n. sp.

n. sp.

Aparchitocythere typica, n. gen., n. sp.

chorum (Swain and

censis Swain and

Camptocythere ettiptica, n. sp.

Swain and Peterson.

Swain and Peterson.

Progonocythere hieroglyphica Swain and 

Peterson.

Progonocythere crowcreekensis Swain and 

Peterson.

Protocythere quadricarinata, n. sp.

Us, n. sp.

(complete shells).

TmTnat.nrp. valves

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

(complete shells).

a

49(23)

31

18

'

b

8(4)

72

76

8(4)

2

6

c

26(13)

18

12(4)

1

d

168(60)

90

37

41

57(Iej

34

12

11

11

1

e

9 Cl'>

4

5

2(1)

276(122)

1Q/Q\

oo

f)(1\

?9

f

i 74(8)

40

26

6(2)

8(2)

8

3

2

g

186(5)

140

144

28(13)

24(6)

10

4

10

OQ f7\

91 (ti\

4

4(2)

QA/OFft

74

6

h

369(116)

206

33

isn

14(7)

132(51)

94

20

18

51(23)

?4

?47

iO\

4

53(26)

?9

t){\fn\

14

4

i

59

26

19

14

q(11

12(5)

2

94(38)

28(12)

?28

/»/i\

3

3

17(8)

?4

j

135(29)

84

28

23

22(11)

8

194(90)

49(23)

?2

747

JO

22

17

4

Ad (991

156(69)

106

26

24

k

243(36)

148

19

76

5(2)

4Q/94\

4

176(53)

77

7169

10

1

7

2

142(71)

76

•

186(33)

152

18

16

1

15(7)

14

1

61(30)

47

4

10

1

71

1

1

IftfQt

16

2

m

116(57)

38

70

8

280(139)

224

26

30

12(6)

712

1

1

9(11

n

68(33)

10

46

12

111(55)

95 ,

2

14

44(22)

710

727

77

6

6

o

73(35)

764

72

7

P

103(51)

73

18

712

1 The "number of valves" includes in each instance both single valves and whole specimens; the numbers in parentheses are of complete shells. Numbers of male and 

femal.e valves are given where dimorphism is recognized, but in Camptocythere elliptica the figures are tentative because of difficulty in distinguishing male dimorphs from immature specimens. For example, Cytherella paramuensteri is represented at locality J-61f by 74 valves of whic<> 16 are 8 complete shells and the remaining 58 are separated 

valves. Forty of the total of 74 valves are interpreted as adult males, 8 are adult females and 26 are immature valves.

Samples from Swift formation of Montana

Height (in feet) 

above base of 

Area and sample formation

Southwest corner of Red Dome, east of Bridger, in Pryor 

Mountains, Sec. 19, T. 7 S., R. 24 E., Carbon County, 

Mont. (Locality 6 on fig. 1.) 

Sample: J-10a_—__________________________ At base

10b____ Upper part of 7-ft basal sandstone bed

10c_________________________________ 15

lla_________________________________ 20-23

lib...._-_.___._-_-__..._..._.___.._ 26

llc_________________________________ 29-33

lid._-_----___-___-_-_._____________ 40

12a_._____-________.__.._..__„.._. 40-45}.

12b.__ —___________________________ 45&-51

Samples from Swift formation of Montana—Continued

Height (in feet) 

above base of 

Area and sample formation

Along east side of road, J^ to 1 mi north of gypsum factory 

in Sec. 2, T. 14 N., R. 19 E., and Sec. 35, T. 15 N., R. 

19 E., near Heath, Fergus County, Mont. (Locality 7 

on fig. 1.)

Sample J-14a____._______.... ——————— -- 6-11

One mi southwest of Piper on the northwest corner of the 

escarpment due east of Bacon Ranch, Sec. 17, T. 14 N., 

R. 20 E., Fergus County, Mont. (Locality 8 on fig. 1.)

Sample J-19_______________._.__ — _ Basal layers

One mi southwest of Landusky, Sec. 32, T. 25 N., R. 24 E., 

Little Rocky Mountains, Phillips County, Mont. (Locality 9 on fig. 5.)
OSTRACODES FROM THE UPPER PART OF THE STJNDANCE FORMATION

Sample from Swift formation of Montana—Continued

Area and sample

One mi southwest of Landusky—Continued 

Sample: J-22a__ ___________________

22b..___ __________________

22c.______ _____________

Height (in feet)

above base of

'ormatlon

13

22

25

29

Sample from Swift formation of Montana—Continued

Area and sample

One mi southwest of Landusky—Continued 

Sample: J-22j_____________________

Height (in feet)

above base of

formation

37

50

Gorge of Shoshone River, 2 mi west of Cody, Wyoming.

(Locality 10 on fig. 1.) 

Sample: J-43b..______.__. — __ — --_--- — --_ — -. 5-10

43c_ ___-_-_----_-------------------_ 10-15

Distribution of ostracodes in the Swift formation of Montana 

[B=l-5, LC=6-15, C = l&-25, A=2&-50, and VA=more than 50 specimens.]

Cytherettoidea sp __________

CythereHoidea? sp_._ _ ..

Leptocythere imlayi... __

Cytherural lanceolata .....

C.I sp....— .............

tea.

P.?SP —— - —— —— —— __..——

Bythocypris? sp ______

new genus resembling

Theriosynoecum. 

new genus resembling

new genus resembling

a

E

E

LC

J-10

b

A

C

LC

c

LO

E

R

a

C

Jb

C

C

11

c

R

R

LC

C

d

R

LC

LC

A

Ja

LC

12

b

LC

J-14

LC

LC

LC

C

A

C

R

E

J-19

E

LC

LC

LC

LC

E

a

E

A

b

LC

T-0

LC

c

E

E

d

LC

R

R

J-22

f

E

LC

E

LC

R

g

VA

A

VA

h

A

.

C

C

1

LC

Jb

LC

LC

A

A

43

C

A

E

LC

ANCESTRAL RELATIONSHIPS OF THE REDWATER 

OSTRACODES

The late Paleozoic and the described Mesozoic ostracodes are, for the most part, very different. Perhaps 

the keys to their interrelationships lie in the almost 

entirely unknown Triassic faunas. Among the very 

few genera of Permian ostracodes that also occur in 

Jurassic rocks are Paraparchites Ulrich and Bassler, 

Eridoconcha Ulrich and Bassler, Bairdia McCoy, 

CythereUa Jones, Bythocypris Brady, Macrocypris Brady, 

Pontocypris Sars, and Monoceratina Roth. The Permian genus Tomiella Spizharsky is very close to, if not 

the same as, Limnocythere Brady of the Cenozoic.

Doubt can be raised in practically all of these 

instances as to the equivalence of the Paleozoic genera 

and those in younger rocks, particularly because of the 

generally simpler muscle-scar patterns of the Paleozoic 

species. If they are not congeneric however, the 

Paleozoic species and those of the Mesozoic and Cenozoic are strikingly homeomorphic. Until the Triassic 

ostracodes are better known and the details of shell 

structure in the late Paleozoic ostracodes have been 

more thoroughly studied, comparisons between many

late Paleozoic and Mesozoic ostracodes will remain 

largely subjective. The following tentative suggestions 

concerning the relationships of several groups of ostracodes are based on Swain's studies of various ostracode 

faunas, and examination of type specimens in the United 

States National Museum.

The Cytherellidae of the Mesozoic do not differ in 

principal shell features from those of the Permian. 

The distinction between Cavellina Coryell (emended 

Kellett, 1935, p. 144) in which the posterior inner 

transverse ridge of the females is long, and CythereUa 

Jones in which this ridge is shorter, is very obscure. 

CythereUa paramuensteri, n. sp. of the Upper Jurassic 

has the posterior ridge and corresponding external 

transverse depression extending from the dorsal to the 

ventral margin, and if the species had been found in 

the Paleozoic would very likely have been referred to 

Cavellina. Swain feels that there is little value in retaining Cavellina and recommends that it be discarded 

or reduced to the status of a subgenus.

The Bairdiidae also seem to continue with relatively 

little change from the Permian into the Mesozoic. 

The hinge structures of the Mesozoic Bairdia are poorly 

known, and many of the species may eventually be
8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

referred to Bairdoppttlata Coryell, Sample and Jennings, 

in which denticulations occur on the selvage along the 

dorsal slopes.

Marine Cypridae, such as Paracypris Sars, are present 

both in Paleozoic and in younger rocks and, although 

the muscle scars of the Paleozoic species are simpler 

than those in the Mesozoic and Cenozoic species 

(Scott, 1944, p. 163), there is little to distinguish them 

generically. The marine Cypridae are not important 

elements in most fossil ostracode faunas.

The roots of the Cytheridae, which dominate postPaleozoic marine ostracode faunas, are obscure, but it 

seems very possible that the family is polyphyletic. 

Kellett (1935, p. 155) concluded that the Pennsylvanian 

and Permian Basslerella Kellett is the direct ancestor 

of Cytheridea because of the general shape, weakly 

creiiulate hinge, and calcified inner lamellae of the 

former. Swain examined types of species of Basslerella, 

and observed these features in B. crassa Kellett (the 

type of the genus), but feels that the other species are 

less certainly representative of the Cytheridae and 

. perhaps are closer to the Cypridae.

Ellipsella distenta Kellett (1933, p. 82, pi. 13, figs. 

18-20) from the Pennsylvanian Howard limestone of 

Kansas is much like AparcMtocythere Swain and Peterson, n. gen., in outline, nearly straight hinge margin, 

and in the slight but clear differentiation along the 

hinge of the left valve to form weak terminal teeth 

(rather than left valve sockets in AparcMtocythere), 

an interterminal weak, perhaps slightly crenulate bar 

and a weak groove dorsal to the bar. The writers 

would orient the species so that the more truncated, 

higher end is posterior, making the right valve the 

larger and placing the weak sulcus anterior to midlength. 

Other specimens figured by Kellett from the lower 

Permian (1933, pi. 13, figs. 14-16) may represent a 

different species. Ellipsella (Coryell and Rogatz, 1932) 

is placed in the Kloedenellidae by Kellett who states 

however that, "* * * it might well belong in the 

Glyptopleuridae, the hingement apparently being 

similar to that of the latter genus [family]" (Kellett, 

1933, p. 82). The present writers offer another suggestion: that its outline and submedian pit or weak 

sulcus ally Ellipsella with Graphiodactylus Roth for 

which Kellett (1936, p. 772) proposed the family 

Graphiodactylidae. We suggest that AparcMtocythere, 

n. gen., representing one section of Jurassic Cytheridae, 

is related to Ellipsella Coryell and Rogatz of the Pennsylvanian and Permian, which in turn may be descended from Graphiodactylus Roth of the Devonian 

and Mississippian.

The holotype of Kirkbya lindahli Ulrich from the 

Warsaw limestone, Mississippian, at Columbia, Illinois, 

is the genoholotype of Savagella Geis (1932, p. 168) of

the family Kirkbyidae. The specimen, here called a 

left valve, is subquadrate with an abraded but straight, 

apparently simple hinge; the anterior cardinal angle 

is much more obtuse than the posterior; the external 

surface has an anteromedian node and postjacent 

furrow, a well-developed marginal rim, and coarse 

surface reticulations. The valve interior is filled with 

matrix. This species or a related form may lie in the 

ancestral stock of the Jurassic genus Progonocythere 

Sylvester-Bradley which is represented in the Redwater fauna by P. hieroglyphica Swain and Peterson 

and P. crowcreekensis Swain and Peterson. The hinge 

of Progonocythere is more advanced in that it bears 

terminal crenulate elements.

Protocythere Triebel, which is represented by several 

species in the Cretaceous, and now has been found in 

the Redwater shale member of the Sundance formation, 

may be descended from Basslerella Kellett. As stated 

above Basslerella is believed by Kellett to be ancestral 

to the cytherideids of the Mesozoic. Protocythere 

closely resembles Haplocytheridea Stephenson and other 

typical cytherideids in hingement and general form, 

but differs in its longitudinal pattern of ridges and more 

compressed posterior end.

The ancestral relationships of the Redwater species 

of Monoceratina Roth, Leptocythere Sars, Cytherura 

Sars, Camptocythere Triebel, and Cythereis Jones are 

obscure. The Redwater species of the first four genera 

have in common weak ventral alae or swellings, and all 

five genera resemble Aparchitocyihere, n. gen., whose 

left valve is the larger, but whose right valve extends 

beyond the left along the hinge and the hinge bears 

only weak simple terminal teeth and sockets. Whether 

these similarities are phyletic or merely hoineomorphic 

only additional study of material from older deposits 

will reveal. Monoceratina is found in rocks as old as 

Middle Devonian. It is not clear whether the Mesozoic 

and Cenozoic "Monoceratina," are congeneric with 

those of the Paleozoic. Swartz (1936, p. 554) placed 

the genus in the Acronotellidae, but post-Paleozoic 

species are generally placed in the Cytheridae.

The ancestry of Cythereis is also obscure. The females of (7.? zygoventralis, n. sp. are very similar in 

general shape, marginal rim and strong longitudinal 

ridges in the ventral half, to some species of Amphissites Girty of the middle and late Paleozoic. The 

hinge of Cythereis, consisting of an anterior socket and 

tooth, interterminal bar or groove and posterior socket 

or tooth, is the most advanced type of ostracode hinge. 

Indirect support of a possible relationship of the genus 

to Amphissites is that the hinge of the latter is relatively 

much more advanced than that of other Paleozoic 

ostracodes, and typically bears terminal sockets and 

teeth (Kellett, 1933, p. 93). The present writers
OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION 9

would reverse the orientation of Amphissites used by 

Kellett and refer to the more broadly rounded end as 

anterior. The writers believe that there may be an 

ancestral relationship between Amphissites and Cyihereisl zygoventralis but, as explained in the description 

of the species, it is not clear whether (7.? zygoventralis 

represents Cythereis or a new genus.

DESCRIPTION OF SPECIES

Order OSTRACODA latreille, 1802

Suborder PLATYCOPA Sars, 1866

Family CYTHERELLIDAE Sars, 1866

Genus CYTHEREILA Jones, 1849

Cytherella paramuensteri Swain and Peterson, n. sp.

Plate 1, figures 1-7

Shell subquadrate in lateral view; dorsal margin 

nearly straight, about two-thirds of shell length; ventral margin slightly concave medially, subparallel to 

dorsum; terminal margins broadly rounded, posterior 

truncate below midheight. Right valve larger than 

left, overlapping and extending beyond the other 

around entire periphery, most strongly along dorsum 

and ventrum. Valves compressed, but with female 

dimorphs inflated in posterior fifth. Surface very 

slightly depressed in mid-dorsal region; a small pit, 

the external expression of the muscle scar, lies just 

dorsal to midheight; general surface smooth except for 

very minute, closely spaced pits on marginal portions 

of valves.

Margin of right valve grooved for reception of edge 

of left; along hinge, groove slightly deeper than elsewhere, and posteriorly very shallow. Muscle scar a 

small, slightly dorsomedian elevation, consisting of four 

or five longitudinally elongated spots. Inner lamellae 

and pore canals lacking.

Length of holotype (U.S.N.M. 117957), a female 

shell, 0.83 mm, height 0.45 mm, thickness 0.32 mm. 

Length of a male paratype (U.S.N.M. 117958, pi. 1, 

fig. 2) 0.72 mm, height 0.30 mm, thickness 0.26 mm.

Relationships.—This species closely resembles C. 

muensteri (Roemer) of the Cretaceous in the tiny surface pits of the females, but is more subquadrate. It 

is also closely similap to other species of Cytherella that 

occur in the Lower Cretaceous and Upper Jurassic of 

the Gulf of Mexico region (Alexander, 1929, pp. 47-49; 

Swain, 1949, pi. 3), particularly C. scotti Alexander and 

C. comanchensis Alexander, but dimorphism in these 

species has not been well demonstrated. Adult specimens apparently are far outnumbered by immature 

molts in the present collections. Among the adults 

the smaller, less convex, males are more numerous than 

the females. ^ '

993981—52———3

Occurrence.—(1) Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; localities J-61e-n. (2) Swift formation, 

Red Dome, Sec. 19, T. 7 S., R. 24 E., Carbon County, 

Montana; J-lla-d, J-12b. (3) Swift formation, 

near Heath, Sec. 2, T. 14 N., R. 19 E. and Sec. 35, T. 

15 N., R. 19 E., Fergus County, Montana; J-14a. (4) 

Swift formation, Shoshone River Gorge, 2 miles west of 

Cody, Wyoming; J-43b. (5) Specimens probably 

representing this species also occur in the lower part of 

the Sundance formation in Wyoming.

Cytherella ventropleura Swain and Peterson, n. sp. 

Plate 1, figures 10-12

Shell minute, ovate in lateral view; highest near 

anterior end; dorsal and ventral margins slightly convex, ventrum straightened medially; anterior margin 

broadly rounded, posterior margin narrower and slightly 

extended medially. Right valve larger than left, extending beyond the other most noticeably along 

ventrum. Valves compressed except for postventral 

broad longitudinal swelling on surface of each valve; 

general surface very finely pitted.

Hingement consists of simple groove in right valve 

for reception of edge of left. Muscle scar not clearly 

seen but seems to consist of a large circular spot situated 

near anterior end of postventral external swelling, and 

well in front of midlength. Inner lamellae lacking.

Length of holotype (U.S.N.M. 117963) 0.27 mm, 

height 0.19 mm, thickness 0.12 mm.

Relationships.—The posteroventral longitudinal 

swelling serves to distinguish this species. It is also 

distinguished by its small size, and the present specimens possibly represent immature molts. The hingement, overlap relationships, and lack of inner lamellae 

ally the species with Cytherella Jones.

Occurrence.—Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61f, g, i, k.

Suborder PODOCOPA Sars, 1866

Family CYPRIDAE Baird, 1846

Genus MACROCYPRIS Brady, 1867

Macrocypris minutus Swain and Peterson, n. sp.

Plate 1, figures 13-16

Shell sublanceolate in side view; highest about onethird from anterior end; dorsal margin moderately 

convex, slightly truncate behind and in front of point 

of greatest height; ventral margin nearly straight; 

anterior margin rounded, extended medially; posterior
10 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

margin bluntly acuminate, strongly extended below. 

Right valve larger than left, extending beyond the 

other along ventrum and along dorsal slopes. Valves 

compressed, thickest medially.

Hingement simple; hinge surface of left valve 

slightly beveled above, along dorsal slopes, for reception 

of overlapping edge of right. Inner lamellae fairly 

broad; line of concrescence and inner margin coincide. 

Muscle scar not clearly observed but appears to consist 

of a slightly dorsomedian group of four spots of which 

the dorsal two are the largest. Neither radial nor normal canals were observed.

Length of holotype (U.S.N.M. 117965) 0.39 mm, 

height 0.18 nun, thickness 0.07 mm.

Relationships.—This species is less elongated and 

smaller than most other described members of Macrocypris. The overlapping right valve relates it to this 

genus although living species are much larger. Specimens described by Cooper (1946, pp. 61, 62) from the 

Pennsylvanian and by Alexander (1929, p. 59) from 

the Cretaceous are generally smaller than 1 mm, whereas living species are as much as 3 mm or more in length.

Occurrence.—(1) Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61e, h-k. (2) Swift formation, near Heath, 

Sec. 2, T. 14 N., R. 19 E. and Sec. 35, T. 15 N., R. 19 E., 

Fergus County, Montana; J-14a. (3) One mile southwest of Landusky, Sec. 32, T. 25 N., R. 24 E., Phillips 

County, Montana; J-22c, f.

Family CYTHERIDAE Baird, 1850

Genus APARCHITOCYTHERE Swain and Peterson, 

new genus

Shell subovate to subquadrate; hinge margin nearly 

straight, frequently occurring mostly posterior to point 

of greatest height; ventrum gently convex to sinuous; 

terminal margins broadly rounded. Left valve larger 

than right, but right overlaps left along hinge. Valves 

strongly convex. Surface not strongly ornamented.

Hinge of left valve consists of a terminal short 

elongate socket-groove, and an inter terminal narrow bar 

with weak groove behind it. Hinge of right valve 

consists of corresponding terminal elongate tooth elevations formed of valve edge, and an interterminal groove. 

Inner lamellae distinct and heavily calcified but narrow; 

line of concrescence and inner margin slightly separated. 

Radial canals few and widely spaced; normal canals 

likewise few. Muscle scar consists of a median vertical 

row of three or four spots, and two more anterior spots; 

a low obscure transverse ridge lies on valve interior 

just behind muscle scar. In the type species, female 

dimorphs larger and more subquadrate than males.

Type species.—Aparchitocythere typica Swain and 

Peterson, n. sp.

Geologic Range.—Upper Jurassic. The species described as Apatocythere? loeblichorum Swain and Peterson 

(1951) from the Red water shale member of the Sundance formation are referred to Aparchitocythere (see 

p. 11). An undescribed species of the genus occurs in 

the lower part of the Sundance formation.

Aparchitocythere typica Swain and Peterson, n. sp. 

Plate 1, figures 8, 9, 17, 18, 21, 22

Shell subovate to subquadrate in side view. Dimorphism prominently exhibited, with males shorter, more 

ovate in outline than females. Dorsal margin moderately convex in males, straighter but somewhat sinuous 

and about three-fifths of shell length in females. 

Ventral margin slightly convex in males, sinuous in 

females. Anterior margin broadly rounded, slightly 

extended below; posterior margin more narrowly 

rounded and extended medially in males, about equal 

in breadth to anterior and extended above in females. 

Left valve larger than right, overlapping and extending 

beyond the other along free margins; dorsally, right 

valve overlaps and extends beyond left. Valves 

strongly convex, thickest about one-third from posterior 

end; females slightly compressed anterior to position of 

greatest thickness. In some specimens, particularly in 

females, there is a very weak transverse dorsomedian 

furrow that is represented on interior surface by a slight 

ridge. Surface smooth except for widely scattered tiny 

pits that mark external openings of normal canals.

For a discussion of internal features, refer to the 

description of the genus.

Length of male paratype (U.S.N.M. 116641, pi. 1, 

fig. 22) 0.72 mm, height 0.47 mm, thickness 0.40 mm. 

Length of female holotype (U.S.N.M. 116642, pi. 1, 

fig. 9) 0.91 mm, height 0.56 mm, thickness 0.44 mm.

Relationships.—There are no known close relatives of 

this species in the Mesozoic, except Aparchitocythere 

loeblichorum (Swain and Peterson) from the Redwater 

member at its type locality and an undescribed species 

in the lower part of the Sundance. A. loeblichorum is 

much shorter and has the dorsal margin more convex 

than the present species. In the Miocene of the southeastern United States there are several species of 

Basslerites Howe that are similar to the new species in 

shape, but the hinge of Basslerites consists of strong 

knoblike teeth and sockets.

Occurrence.—(1) Upper part of the Sundance or 

Redwater shale member of the Sundance formation, 

Red Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan 

County, Wyoming; J-61d, f-h, 1-p. ,(2) Swift formation, southwest corner of Red Dome, Sec. 19, T. 7 S.,
OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION 11

R. 24 E., Carbon County, Montana; J-lOb, c, lie, d, 

12a. (3) Swift formation, near Heath, Sec, 2, T. 14 N., 

R. 19 E. and Sec. 35, T. 15 N., R. 19 E., Fergus County, 

Montana; J-14a. (4) Swift formation, one mile southwest of Landusky, Sec. 32, T. 25 N., R. 24 E., Phillips 

County, Montana; J-22d. (5) Shoshone River gorge, 

2 miles west of Cody, Wyoming; J-43b, c.

Aparchitocythere loeblichorum (Swain and Peterson) 

Plate 1, figures 19, 20, 23-25

Apatocythere loeblichorum Swain and Peterson, 1951, Jour. Paleontology, vol. 25, p. 799, pi. 113, figs. 3-5.

Shell features that were not observed in the rather 

poorly preserved specimens on which the species was 

based are as follows:

Dimorphism in the species is represented by subovate 

specimens like the holotype, presumably males, and 

more elongated subquadrate specimens, presumably 

females.

The right valve overlaps and extends beyond the 

left along the hinge conspicuously in male dimorphs, 

less so in females. The right valve bears a hinge groove 

for reception of edge of left, and there are small terminal notches in the left valve hinge for reception of 

corresponding slight elevations in right.

The coarse weak surface pitting is supplemented in 

some specimens by a faint and much finer pitting.

Length of female shell (U.S.N.M. 116647, pi. 1, 

fig. 19) 0.44 mm, height 0.30 mm, thickness 0.22 mm. 

Length of a male shell (U.S.N.M. 116649, pi. 1, fig. 23) 

0.38 mm, height 0.30 mm, thickness 0.20 mm.

Occurrence.—(1) Upper part of the Sundance or 

Redwater shale member of the Sundance formation, 

Red Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan 

County, Wyoming; J-61a. (2) One mile southwest of 

Landusky, Sec. 32, T. 25 N., R. 24 E., Phillips County, 

Montana; J-22d. (3) The species was originally described from 100-105 feet above base of the Redwater 

shale member of the Sundance formation at the type 

locality, Sec, 2, T. 7 N., R. 1 E., Butte County, South 

Dakota.

Genus MONOCERATINA Roth

Monoceratina sundancensis Swain and Peterson

Plate 2, figures 1-7

Monoceratina sundancensis Swain and Peterson, 1951, Jour. Paleontology, vol. 25, p. 803, pi. 114, figs. 7-15.

Shell features not given in the original description 

are: left valve extends beyond right along anterior 

dorsal slope, but right valve extends beyond left in 

mid-dorsal region as previously stated; in some specimens swollen ventral surface bears a low alaform ridge.

Length of a figured specimen (U.S.N.M. 116659, pi. 

2, fig. 1) 0.36 mm, height 0.19 mm, thickness 0.18 mm.

Occurrence.—(1) Upper part of the Sundance or 

Redwater shale member of the Sundance formation, 

Red Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan 

County, Wyoming; J-61e-j. (2) Swift formation, Red 

Dome, Sec 19, T. 7 S., R. 24 E., Carbon County, 

Montana; J-l lb,c,d. (3) Swift formation, near Heath, 

Sec. 2,T. 14 S., R. 19 E. and Sec. 35, T. 15 N., R. 19 E., 

Fergus County, Montana; J-14a. (4) Swift formation, 

one mile southwest of Piper, Sec. 17, T. 14 N., R. 20 E., 

Fergus County, Montana; J-19. (5) Swift formation, 

one mile southwest of Landusky, Sec. 32, T. 25 N., R. 

24 E., Phillips County, Montana; J-22a, f, j. (6) The 

species was first described from 40 to 59 feet above base 

of Redwater shale member at its type locality, Sec. 2, 

T. 7 N., R. 1 E., Butte County, South Dakota.

Genus Camptocythere Triebel, 1950

Shell subovate in side view; dorsum moderately to 

strongly convex; ventrum less convex; ends rounded, 

posterior more pointed than anterior. Right valve 

strongly overlaps left dorsally, left valve overlaps right 

ventrally and terminally. Valves moderately convex, 

thickest medially. Surface smooth, pitted and in some 

species with short median sub vertical furrows.

Hinge of right valve consists of terminal small elongate teeth, and intervening narrow bar dorsad of which 

is a broad accommodation groove; hinge of left valve 

consists of terminal weak sockets and intervening narrow 

groove. Muscle scar consists of a median subv-ertical 

row of four spots and two additional more anterior spots. 

Inner lamellae narrow, line of concrescence and inner 

margin nearly or actually coinciding. Radial canals 

simple and widely spaced (after Triebel, 1950).

Type Species.—Camptocythere praecox Triebel, 1950.

Geologic range and geographic Distribution.—Middle 

and upper Jurassic, Europe, North America.

Camptocythere elliptica Swain and Peterson, n. sp.

Plate 2, figures 8-13

Shell elongate-subelliptical in lateral view; hinge 

margin straight to slightly sinuous and half to twothirds of shell length; ventral margin nearly straight 

and subparallel to dorsum; anterior margin broadly 

rounded, slightly extended below, truncate above; posterior margin more narrowly rounded, extended dorsomedially. Left valve larger than right, overlapping 

along free margins and extending beyond right terminally; dorsally, right valve overlaps and extends 

beyond left. Valves moderately convex, thickest postmedially and ventrally,- ventral surface flattened.
12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

A weak sulcus occurs in mid-dorsal region; in presumed female dimorphs valve markedly swollen posterior to sulcus resulting in a slight overhang along 

posterior half of dorsal and ventral margins. In some 

specimens, particularly in females, there is a low, 

rounded, slightly anteromedian node representing the 

position of the adductor muscle scar. Well-preserved 

specimens have surface of valves very finely pitted.

Hinge of right valve consists of terminal small toothlike elevations, of which the anterior is the higher, and 

an inter terminal groove. Hinge of left valve correspondingly consists of terminal shallow sockets and an 

interterminal bar formed of the valve edge. Muscle 

scar a slightly anteromedian vertical row of four spots 

and an additional more anterior spot. Inner lamellae 

of moderate width, broadest anteriorly; line of concrescence and inner margin slightly separated. Radial 

canals few and widely spaced.

Length of holotype (U.S.N.M. 116666, probably a 

female) 0.49 mm, height 0.28 mm, thickness 0.23 mm.

Relationships.—The general shape, flattened ventrum 

and hingement ally this species with Camptocythere 

Triebel. Aparchitocythere Swain and Peterson, n. gen., 

is closely similar but lacks the flattened ventrum and 

ventral swelling of Camptocythere. Monoceratina sundancensis Swain and Peterson, and Leptocythere imlayi 

Swain and Peterson although more elongate and differing in other respects of shape are nevertheless like 

Camptocythere in hingement, flattened ventrum, dorsal 

overlap of right valve, and weak median sulcus. All of 

these forms appear to be ancestrally related, and the 

species we have referred to Monoceratina and Leptocythere may require assignment to new genera.

Occurrence.—Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61f-n.

Genus LEPTOCYTHERE Sars, 1925

Leptocythere imlayi Swain and Peterson

Plate 1, figures 26-30

Leptocythere imlayi Swain and Peterson, 1951, Jour. Paleontology, 

vol. 25, pp. 804-805, pi. 114, figs. 16-24.

Three immature molts and two adult shells of this 

species are illustrated to show the close relationship to 

Monoceratina Roth. In the molts the shell is much 

shorter, more pointed and more strongly extended posteriorly than in the adult. The posteroventral surface 

of the immature valve is swollen to form a slight overhang; the posterior end of the shell is compressed. 

The hinge of the right valve bears slight terminal 

elevations, but is otherwise smooth. The inner lamellae 

are narrow but distinctly developed.

Length of figured adult specimen (U.S.N.M. 116653, 

pi. 1, fig. 27) 0.51 mm, height 0.28 mm, thickness 

0.19 mm. Length of an immature molt (U.S.N.M. 

116654, pi. 1, fig. 28) 0.36 mm, height 0.24 mm, thickness 0.16 mm.

Occurrence.—(1) Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61h-n. (2) Swift formation, near Heath, 

Sec. 2, T. 14 N., R. 19 E. and Sec. 35, T. 15 N., R. 

19 E., Fergus County, Montana; J-14a. (3) Swift 

formation, one mile southwest of Piper, Sec. 17, T. 14 

N., R. 20 E., Fergus County, Montana; J-19. (4) 

Swift formation, one mile southwest of Landusky, 

Phillips County, Montana; J-22J.

Genus CYTHERURA Sars, 1866

Cytherura? lanceolata Swain and Peterson

Plate 1, figures 31-33

Cytherura? lanceolaia Swain and Peterson, 1951, Jour. Paleontology, vol. 25, pp. 802-803, pi. 114, figs..5, 6, 27, 28.

This species is characterized by subovate to subquadrate outline with well defined anterior cardinal angulation; ventral portion of anterior margin extended and 

bluntly acuminate, short posteroventral alae, and right 

valve overlapping along the hinge.

Length of a figured specimen (U.S.N.M. 116656, pi. 

1, fig. 31) 0.39 mm, height 0.23 mm, thickness 0.16 mm.

Occurrence.—(1) Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61e, g, h, i, j, k, m. (2) Swift formation, 

Red Dome, Sec. 19, T. 7 S., R. 24 E., Carbon County, 

Montana; J-llc, d. (3) Swift formation, near Heath, 

Sec, 2, T. 14 N., R. 19 E. and Sec. 35, T. 15 N., R. 19 

E., Fergus County, Montana, J-14a. (4) Swift formation, Sec, 32, T. 25 N., R. 24 E., Phillips County, 

Montana; J-22f. (5) The species was originally described from 40 to 63 feet above base of Redwater shale 

member at its type locality Sec. 2, T. 7 N., R. 1 E., 

Butte County, South Dakota.

Genus PROGONOCYTHERE Sylvester-Bradley, 1948 

Progonocythere hieroglyphica Swain and Peterson

Plate 2, figures 18-20

Progonocyihere hieroglyphica Swain and Peterson, 1951, Jour. 

Paleontology, vol. 25, pp. 800-802, pi. 113, figs. 10-18.

The outstanding shell characteristics of this species 

are: small size (about 0.6 mm long), subquadrate outline; left valve slightly the larger; surface ornamented 

by two or three outer concentric ridges, four or five
OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION 13

postmedian ventral ridges, and several diversely 

arranged anteromedian ridges; a short oblique anteromedian sulcus; hinge of left valve consists of terminal 

elongate denticulate sockets and an interterminal 

weakly crenulate bar; that of right valve the antithesis; 

inner lamellae fairly broad.

Length of a figured specimen (U.S.N.M. 116677) 

0.56 mm, height 0.27 mm, thickness 0.30 mm.

Occurrence.—(1) Sundance formation, Redwater shale 

member, Sec. 3, T. 6 N., R. 2 E., Lawrence County, 

South Dakota; J-47c, e-g. (2) Sundance formation, 

Redwater shale member, Sec 18, T. 45 N., R. 60 W., 

Weston County, Wyoming; J-52f. (3) Sundance formation, Redwater shale member, Sec. 14, T. 7 S., 

R. 3 E., Fall River County, South Dakota; J-56d. (4) 

Upper part of the Sundance or Redwater shale member, 

Red Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan 

County, Wyoming; J-61b. (5) Swift formation, Red 

Dome, Sec. 19, T. 7 S., R. 24 E., Carbon County, 

Montana; J-lOa. (6) Swift formation, one mile southwest of Piper, Sec. 17, T. 14 N., R. 20 E., Fergus County, 

Montana; J-19. (7) Swift formation, one mile southwest of Landusky, Sec, 32, T. 25 N., R. 24 E., Phillips 

County, Montana; J-22b, c, d, f, g. (8) Swift formation 

Shoshone River Gorge, 2 miles west of Cody, Wyoming; 

J-43b. (9) The species was originally described from 

33-73«feet above base of Redwater shale member of 

Sundance formation at its type locality in Sec. 2, T. 

7 N., R. 1 E., Butte County, South Dakota.

Progonocythere crowcreekensis Swain and Peterson 

Plate 2, figures 22-25

Progonocythere crowcreekensis Swain and Peterson, 1951, Jour. 

Paleontology, vol. 25, p. 802, pi. 114, figs. 1-4.

This species is characterized by subquadrate outline, 

coarsely reticulate and pustulose surface, prominent 

anteromedian tubercle, and anteroventral marginal 

spines. It is about one-third larger than P. hieroglyphica Swain and Peterson.

Length of a figured female shell (U.S.N.M. 116681, 

pi. 2, fig. 23) 1.07 mm, height 0.52.mm, thickness 0.56 

mm; length of a figured male (U.S.N.M. 116680, 

pi. 2, fig. 22) 0.85 mm, height 0.45 mm, thickness 0.46 

mm.

Occurrence.—(1) Sundance formation, Redwater shale 

member, Sec. 3, T. 6 N., R. 2 E., Lawrence County, 

South Dakota; J-47f. (2) Sundance formation, Redwater shale member, Sec. 18, T. 45 N., R. 60 W., 

Weston County, Wyoming; J-52e, f. (3) Upper part 

of the Sundance or Redwater shale member, Red Gulch, 

Sec. 22, T. 58 N., R. 89 W., Sheridan County, Wyoming; 

J-61b-d. (4) Swift formation, Red Dome, Sec. 19, T. 

7 S., R. 24 E., Carbon County, Montana; J-lOa-c.

(5) Swift formation, Sec. 17, T. 14 N., R. 20 E. } Fergus 

County, Montana; J-19. (6) Swift formation, Sec. 32, 

T. 25 N., R. 24 E., Phillips County, Montana; J-22b, h. 

(7) Swift formation, Shoshone River Gorge, 2 miles 

west of Cody, Wyoming; J-43b. (8) The species was 

described from 40 to 59 feet above base of Redwater 

shale member at its type locality Sec. 2, T. 7 N., R. IE., 

Butte County, South Dakota.

Genus PROTOCYTHERE Triebel, 1938 

Protocythere quadricarinata Swain and Peterson, n. sp.

Plate 2, figures 14-17, 21

Shell sublanceolate in side view; highest about onefourth from anterior end; hinge margin nearly straight, 

about two-thirds of shell length, ventral margin slightly 

convex, converging posteriorly toward dorsum; anterior 

margin rounded, extended below; posterior margin more 

pointed, strongly extended medially. Left valve larger 

than right, extending beyond the other around entire 

periphery, but most strongly along ventrum and along 

dorsal slopes. Convexity of valves moderate, greatest 

thickness posteromedian; middle of each valve flattened 

in some specimens. Ends of each valve slightly compressed but more so in right valve than in left; left 

valve with terminal low marginal rims.

Middle two-thirds of each valve bears four longitudinal low ridges or- swellings; dorsal ridge highest 

medially, narrow behind and broader in front; two 

median ridges merging anterior to midlength; ventral 

ridge barely differentiated from general surface of valve 

below. General surface bears a few scattered pits.

Hinge of left valve consists of an anterior, elongate, 

crenulate socket, a posterior shorter crenulate socket, 

and an interterminal bar the ventral slope of which bears 

an obscurely crenulate weak incision; dorsad of bar is 

an accommodation shelf. Hinge of right valve consists 

of terminal elongate, crenulate teeth; intervening hinge 

edge recessed and in the present material only obscurely 

crenulate. Inner lamellae of moderate width; line of 

concrescence and inner margin coincide) Muscle scar 

not observed.

Length of holotype (U.S.N.M. 116672), 0.65 mm, 

height 0.32 mm, thickness 0.31 mm.

Relationships.—The general shape, overlap, hingement and longitudinal ridges of this form conform to 

Protocythere Triebel. The double median ridge distinguishes it from other described species.

Occurrence.—(1) Upper part of the Sundance or 

Redwater shale member of the Sundance formation, 

Red Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan 

County, Wyoming; J-61c, d. (2) Swift formation, Red 

Dome, Sec. 19, T. 7 S., R. 24 E., Carbon County,
14 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1952

Montana; J-lOb, c. (3) Swift formation, Sec. 32, T. 25 

N., R. 24 E., Phillips County, Montana; J-22f, g.

Genus CYTHEKEIS Jones, 1849

Cythereis? zygoventralis Swain and Peterson, n. sp.

Plate 2, figures 26-32

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

about two-thirds of shell length, and with rather well 

defined cardinal angles of which the anterior is the more 

obtuse; ventral margin nearly straight to gently convex, 

converging slightly with dorsum posteriorly; anterior 

margin broadly rounded, extended below, truncate 

above; posterior margin narrower, sub truncate. Left 

valve slightly larger than right, overlapping slightly 

along ventrum and extending beyond the other anterodorsally and posteriorly. Valves moderately convex, 

thick in ventral half, especially thick in posteroventral 

region.

Surface strongly and coarsely reticulate; dorsal and 

terminal margins bear narrow knife-edge rims; three 

prominent, longitudinal, narrow ridges in middle part 

of each valve: one above and two below midshell. The 

more ventral ridge typically strongly elevated near its 

posterior end and, in side view, overhanging ventral 

margin. Between the two ventral ridges and anterad 

. of midlength is a short fourth ridge. Ends of ridges 

connected except posterior ends of dorsal and ventral 

ridges. Mid-dorsally are two or three short ridgelike 

elevations; anterodorsally, a short spur projects ventrally from marginal rim; a shallow sulcus lies behind 

this spur.

Hinge of right valve consists of an anterior elliptical 

tooth that bears a weak transverse groove, an interterminal groove, broadest anteriorly and very narrow 

medially, and a posterior rounded tooth. Hinge of 

left valve is composed of an anterior socket, an interterminal ridge, and a posterior socket. Muscle scar 

consists of a slightly anteromedian subvertical row of 

four tiny, closely spaced spots and a more anterior spot. 

Inner lamellae of moderate width with smooth inner 

margin. The latter and the line of concresence are 

slightly separated.

Dimorphism in the species is represented by larger, 

more subquadrate specimens that are presumably 

females.

Length of male holotype (U.S.N.M. 116685) 0.82 

mm, height 0.45 mm, thickness 0.35 mm. Length of 

female paratype (U.S.N.M. 116687), 0.89 mm, height 

0.44 mm, thickness 0.35 mm.

Relationships.—Several ostracodes that are illustrated 

but not formally described or named by Brand (1949, 

pis. XI-XIV) as "ostracode 72, ostracode 88b, and

ostracode 89a,b" from the upper part of the Middle 

Jurassic (Dogger) of northwestern Germany resemble 

C.f zygoventralis but Brand's illustrations are not clear 

enough to permit detailed comparisons.

The species lacks the crenulate hinge, median node, 

and except in immature molts the posterior strongly 

elevated points, features typical of Cythereis, but seems 

closer to that genus than to any other. There is a 

slight tendency for the posterior end to be compressed 

and the adjacent surface to have its ornamental ridges 

a little more strongly elevated there than elsewhere, 

features that are reminiscent of Cythereis. For the 

time being the new species will be referred to Cythereis, 

although probably the discovery of related species will 

require establishment of a new genus.

Specimens show a great deal of variation, especially 

in surface ornamentation. In some specimens the 

reticulations are very weak and the longitudinal ridges 

provide almost the only ornamentation; in other 

specimens the reticulations are deeply developed and 

nearly obscure the longitudinal ridges. The strongly 

elevated ventral ridges in the presumed male dimorphs 

provide a subalate appearance, and result in a flattened 

aspect of the ventrum; the female dimorphs lack this 

feature.

Immature molts of the species are rare in the present 

collection except in samples from locality J-61J. The 

surfaces of these immature molts are finely pitted, the 

reticulations are developed only in patches and the 

longitudinal ridges are very delicate but fairly well 

defined; the ridge along the dorsum and the two ventral 

ridges terminate posteriorly in prominent elevations in 

several of the molts, and there is a terminal point on 

the submedian ridge of some molts. The ventral 

ridges in the earlier molts form short but conspicuous 

alae, and the posterior end of the shell is distinctly 

compressed.

Occurrence.—Upper part of the Sundance or Redwater shale member of the Sundance formation, Red 

Gulch, Sec. 22, T. 58 N., R. 89 W., Sheridan County, 

Wyoming; J-61g-l.

REFERENCES

Alexander, C. I., 1929, Ostracoda of the Cretaceous of North

Texas: Univ. Texas Bull. 2907, p. 1-137, 2 figs., 9 pis.,

1 chart. 

Brand, E., 1949, Neue Ergebnisse zur mikropalaontologischen

Gliederung des nordwestdeutschen Dogger und Valendis, in

Bentz, A., Erdol und Tektonik in Nordwestdeutschland, p.

335-348, figs. 1-5, pis. 10-14. 

Cooper, C. L., 1946, Pennsylvanian ostracodes of Illinois: 111.

Geol. Surv. Bull. 70, p. 1-177, figs. 1-36, pis. 1-21, 1 chart. 

Geis, H. L., 1932, Some ostracodes from the Salem limestone,

Mississippian of Indiana: Jour. Paleontology, vol 6, pp.

149-188, pis. 22-26.
OSTRACODES FROM THE UPPER PART OF THE SUNDANCE FORMATION 15

Imlay, R. W., 1944, Marine Jurassic of Black Hills area, South 

Dakota and Wyoming: Bull. Am. Assoc. Petroleum 

Geologists, vol. 31, p. 227-273, 3 figs.

———— 1949, Paleogeography of Jurassic seas in the western 

interior of the United States: Rept. of the Committee on a 

Treatise on Marine Ecology and Paleoecology 1948-1949, 

no. 9, p. 72-104, 1 table, 8 figs.

Imlay, R. W., Gardner, L. S., Rogers, C. P., Jr. and Hadley, 

H. D., 1948, Marine Jurassic formations of Montana: 

U. S. Geol. Survey Prelim. Chart 32, Oil and Gas Invest. Ser.

Kellett, B., 1933, Ostracodes of the Upper Pennsylvanian and the 

Lower Permian strata of Kansas: I. The Aparchitidae, 

Beyrichiidae, Glyptopleuridae, Kloedenellidae, Kirkbyidae 

and Youngiellidae: Jour. Paleontology, vol. 7, pp. 59-108, 

pis. 13-16.

———— 1935, Ostracodes of the Upper Pennsylvanian and the 

Lower Permian strata of Kansas: III. Bairdiidae (concluded), Cytherellidae, Cypridinidae, Entomoconchidae, 

Cytheridae and Cypridae: Jour. Paleontology, vol. 9, pp. 

132-166, pis. 16-18.

———— 1936, Carboniferous Ostracodes: Jour. Paleontology,

vol. 10, pp. 769-785. 

Loeblich, A. R., Jr. and Tappan, Helen, 1950a, North American

Jurassic Foraminifera: I. The Type Redwater Shale (Oxfordian) of South Dakota: Jour. Paleontology, vol 24, pp.

39-60, pis. 11-16.

Loeblich, A. R., Jr. and Tappan, Helen, 1950b, North American 

Jurassic Foraminifera: II. Characteristic western interior 

Callovian species: Jour. Wash. Acad. Sci., vol. 40, pp. 1-19.

Scott, H. W., 1944, Muscle scar patterns on some upper Paleozoic 

ostracodes: Jour. Paleontology, vol. 18, pp. 162-171, 28 

text figs.

Swain, F. M., 1949, Upper Jurassic of northeastern Texas: Bull. 

Am. Assoc. Petroleum Geologists, vol. 33, pp. 1206-1250, 

3 pis., 10 figs., 3 tables.

Swain, F. M. and Peterson, J. A., 1951, Ostracoda from the 

Redwater shale member of the Sundance formation at the 

type locality, Butte County, S. D.: Jour. Paleontology, 

vol. 25, pp. 796-807, pis. 113, 114.

Sylvester-Bradley, P. C., 1948, Bathonian ostracodes from the 

Boueti bed of Langton Herring, Dorset: Geol. Mag., vol. 

85, no. 4, pp. 185-204, figs. 1-7, pis. 12-15.

Triebel, E., 1938, Ostracoden-Untersuchungen: I. Protocythere 

und Exophthalmocythere, zwei neue Ostracoden-Gattungen 

aus der deutschen Kreide: Senckenbergiana, vol. 20, pp. 

179-200, pis. 1-3.

———— 1950, Camptocythere, ein neue Ostracoden-Gattung aus 

dem Dogger Norddeutschlands: Senckenbergiana, vol. 31, 

pp. 197-208, pis. 1-3.

INDEX

[Italic numbers indicate descriptions]

K Page

Abstract.—.____.______________.___.__________ 1 

Amphissiles................................................................... 8,9

Aparchitocy there......—-—.........__..———————————————_ 8,10,12

loeblichorum.........______________..__.__... 1,6,7,10,11, pi. 1

typica............................................................ 1,6.7,10, pi. 1

Apatocythere loeblichorum................................__....._____ 10,11

Asiartefrasttis.----------------------------------------_--—------____ 5

asteriscus, Pentacrinus............................................—____ 5

B

Bairdla...........................................______________... 7

Bairdiidae—-__...._._.—....___———.—————_-.—_. 7-8

BairdopWuta.................._.__..___._._.—...._._._..... 8

Basslerella.................................................................... 8

crassa..—__________________.....____—________ 8

Basslerites- ____________________________________ 10

Bythocypria................................................................... 7

sp._——..—-._.——_.__.-.—__._._._——.-—————......... 7

C 

Camptocythere.............................................................. 8,77,12

ettiptlca............................................................ 1,6, 77, pi. 2

praetor..... .............................................................. 11

Camptonectes.. _________________________________. 4 

Cavettina..................................................................... 7

comanchensis, Cytheretta.— _________..._______________ 0 

Corbicettopsis inornata................................__.__________ 5

crassa, Bassleretta................................_____._______.. 8

crowcreekewis, Progonocythere-....._____—————...—.._ 1,6,7,8, 13, pi. 2

curta, Eumlcrotls......................................................____ 5

Cypridae_____________________________________ 1,^,9 

Cyihereh......................................................._______. 8

iygofemrtfis.................................................... 1,6, S, 9, IS, pi. 2

Cytherella-......................................___.-...___.....__.. 7

comanchensts.............................................................. 9

paramuensieri..................................................... 1,6, 7,6, pi. 1

scotti..............................................................____ 9

eentropleura.. __________________________.._ 1,6,8, pi. 1 

Cytherellidae..———————„—-——-————————— 1,7,9

Cytherettoldeasp...........................................—................. 7

Cytheridae._____________....__...-_.__._______.. 1,8-9,10

Cytheridea.................................................................... 8

sp————.———....——.....................—.———....—......_.. 1

Cytherura—.................................................................. 8

lanceolata......................................................... 1,6,7,7*, pi. 1

sp..———_....._..._._______...._.___.______....... 7

D

distenta, Ettipsella.

E 

Ettipsetta..................................................................... 8

dlstenta....________________.________________ 8

ellif'tica, Camptocy there................................................. 1,6,77, pi. 2

Erldoconcha................................................................... 7

monopleura............................................................... 1

Eumicrotis curta.............................................................. 5

orbieutata................................................................. 5

fragilis, Astanet.

G

Qlyptopleurldac—————_..___._...————————..._._..... 8 

Graphiodactylus__________________________________ 8 

Gryphaea nebrascensin......................................................... 3

Gypsum Spring formation, sections______——...——....________ 3-4, 5

H

Haplocytheridea..___„...________———————.——..._____ 8 

hteroglyphica, Progonocythere........................................ 1,6,7,8, IS, pi. 2

Hulett sandstone member, sections. ________________________ 3,4,5

Imlay, Ralph, and Loeblieh, A. R., Jr., sections measured-_________ 2-7

specimens collected_____________—_-____________ 1

imlayi, Lepiocythere................................................... 1,6,7,7*. pi. 1

inornata, Corbicellopsis........................................................ 5

Introduction...__________________________________ 1

Kirkbya lindahll—...........

Kirkbyidae...____.__. 

Kloedenellidae.______. 

Kootenai formation, seetion.

Lak member, sections._.___..———....———.—————————.——— 4,5

lanceolata, Cytheruraf................................................. 1,6,7,7#, pi. 1

Leptocythere.................................................................. 8,12.

imlayi............................................................ 1,6,7, H, pi. 1

Llmnocythere................................................................. 7

UndahJi, Kirkbya.............................................................. 8

Localities, list and map___________________——._.____ 2 

Loeblieh, A. R., Jr., specimens collected by...______....—_______ 1

loeblichorum, Apaiocyihere....-................................................ 10

loeblichorum, AparMiocy there— ---------——.————.——————.-.-. l,6,7,77,pl. 1

M 

Macrocypris.................................................................. 7

mlnuius........................................................... 1,6,7,0, pi. 1

Monoceratina—....................—....................................... 7,8,12

sundancensis...................................................... 1,6,7,77,pi. 2

monopleura, Eridoconcha.. _______________.__--------------_- 1

Morrison formation, sections______________________...._. 2-3,4

nebrascensis, Gryphaea.

orbiculata, Eumicrotis. 

Orthonotacythere.......

Ostra esp...__——.

Pachyiemhissp...............————————————————————————... 5

Paracypris—.................................................................. 8

paramuensteri, Cyiherdla............................................... 1,6,7,9,pi. 1

Paraparchites............... ————— ———————————————————. —.... 7

sp___________________.___________________-. 1 

Pentacrinus asteriscus.......-. .............................. ——————.—— 5

Pleuromya subeUiptica........................................................ 5

Pontocypris................................................................... 7

praecox, Camptocy there...............—...................................... 11

Progonocythere——————————————————————————————————— 8 

crowcreekensis—-—--—---.----——......——....——...—— 1,6,7,8, 13, pi. 2

hieroglyphica.— —............................................. 1,6,7,8, IS, pi. 2

sp.....__--...„-._------—-----.------.———.——-——'-——... 7

Protocythere.............. ——————————— —————————————..———— 8

guadricarinata.---.----—----..—................................ 1,6,7, IS, pi. 2

Q

guadricarinnia, Protocythere. —————————————————— —————— 1,6,7,73, pi. 2 

QuenstedriasuMerts---..............—.................. ——————————— 5

R 

Red water shale member, distribution of ostraeodes........ —————————— B

sections_________________________————————-———— 3,4,5 

Relationships, ancestral, of Redwater ostraeodes..—. —————————————— 7-9

S 

Savagettu...................................................................... 8

scottt, Cytherella-............................................................. 9

Spearfish formation, section......———————————————————————— 4

Stockade Beaver shale member, sections..——————————————————— 3,4,5 

subettiptica, Pleuromya.—.................................................... 5

subleeis, Ouenstedtia...............................................—————— 5

Sundance formation, sections________——— ————.. ————— „—— 3-5 

sundancensis, Monoceratina......................................—... 1,6,7,77, pi. 2

Swift formation, distribution of ostraeodes__„—...—————————————— 7 

..___...___.....„..,._.———......-.-.-———„ 6-7

T 

Theriosynoecum.................————————————————————————— 7

Tomidla...................................................................... 7

typica, Aparchitocythere................................. ——————.. 1,6,7, 10, pi. 1

V 

ventropleura, Cytherella.. ----------—— —————————————————— —1,6,0,pi. 1

Z 

tyoeemralis, Cythereis............................................... 1,6,8,9,73,pi. 2

17

PLATES 1, 2
PLATE 1

FIGURES 1-7. Cytherella paramuensteri Swain and Peterson, n. sp. (p. 9)

1, 7. Left side and posterior views of holotype, Loc. J-61h, U.S.N.M. 117957.

2. Interior of paratype female right valve partly filled with matrix, Loc. J-61k, U.S.N.M. 117958. 

3-6. Interior of paratype female left valve, ventral view of paratype female shell, and dorsal view of paratype female

shell, and ventral view of paratype male shell, Loc. J-61h, U.S.N.M. 117959-117962. All views X50. 

10-12, Cytherella ventropleura Swain and Peterson, n. sp. (p. 9)

11. Left side of holotype, Loc. J-61g, U.S.N.M. 117963. 

10, 12. Posterior and dorsal views of paratypes, Loc. J-61g, U.S.N.M. 117964. All views X74.

13-16. Macrocypris minutus Swain and Peterson, n. sp. (p. 9) 

13. Left side of holotype, Loc. J-61k, U.S.N.M. 117965.

14-16. Left valve interior, ventral view and dorsal view of three paratypes, Loc. J-61k, U.S.N.M. 117966, 116639-116640.

All views X71. 

8,9,17, . 

18, 21, 22. Aparchitocythere typica Swain and Peterson, n. gen., n. sp. (p. 10)

9. Left side of holotype (U.S.N.M. 116642), a female X55, Loc. J-61h. 

8. Ventral view of a female paratype, X55, Loc. J-61h, U.S.N.M. 116643. 

17, 18, 21. Left valve interior, right valve interior and ventral views of three male paratypes, X56, Loc. J-61h, U.S.N.M.

22. Right side of male paratype, X56, Loc. J-61h, U.S.N.M. 116641. 

19, 20, 23-25. Aparachitocythere loeblichorum (Swain and Peterson) (p. 11).

19. Right side of female shell, X86, Loc. J-61a, U.S.N.M. 116647. 

20, 23-25. Right side, dorsal view, left valve interior, right valve interior of four male specimens, X93, Loc. J-61a, U.S.N.M.

116648-116651.

26—30. Leptocythere imlayi Swain and Peterson (p. 12).

26, 27. Dorsal view and right side of two shells, X76, Loc. J-61J, U.S.N.M. 116652, 116653. 

28-30. Right side and ventral views of an immature specimen and interior of an immature right valve, X72, Loc. J-61k,

U.S.N.M. 116654, 116655. 

31-33. Cytherura? lanceolata Swain and Peterson (p. 12).

Left side, dorsal and ventral views of three specimens, X92, Loc. J-61J, U.S.N.M. 116656-116658.
GEOLOGICAL SURVEY PROFESSIOTVAI PAPER 2l3 PLATE L

CYTHERELLIDAE, CYPRIDAE AND CYTHERIDAE
GEOLOGICAL SURVEY PROFESSIONAL PAPER 243 PLATE 2

CYTIJERIDAE
PLATE 2

FIGURES 1-7. Monoceratina sundancensis Swain and Peterson (p. 11).

1-4. 6, 7. Right side, left side, left valve interior, right valve interior, dorsal view of five specimens, X75, Loc. J-61e, U.S.N.M.

116659-116663. 

5, b. Posterior view, ventral view, X75, Loc. J61j, U.S.N.M. 116664, 116665.

8-13. Camptocythere elliptica Swain and Peterson, n. sp. (p. 11). 

8. Right side of holotype, X71, Loc. J61j, U.S.N.M. 116666.

9-13. Left side, left valve interior, right valve interior, dorsal view and ventral view of five paratypes, X71, Loc. J-61J,

U.S.N.M. 116667-116671.

14-17, 21.Protocy'there quadricarinata Swain and Peterson, n. sp. (p. 13). 

14. Right side of holotype, X72, Loc. J-61c, U.S.N.M. 116672. 

15-17. Left side, ventral view, and dorsal view of three paratypes, X72, Loc. J-61c, U.S.N.M. 116673-116675.

21. Interior of paratype left valve, partly filled with matrix, X72, Loc. J-61d, U.S.N.M. 116676. 

18-20. Progonocythere hieroglyphica Swain and Peterson (p. 12).

Left side, dorsal view and right side of three specimens, X27, Loc. J-52f, U.S.N.M. 116677-116679.

22-25. Progonocythere crowcreekensis Swain and Peterson (p. 13).

22. Right side of a male shell, X54, U.S.N.M. 116680.

23. Left side of a female shell, X46, U.S.N.M. 116681.

24. Ventral view of a male shell, X44, U.S.N.M. 116682.

25. Interior of a left valve filled with matrix, X46, U.S.N.M. 116683. All from Loc. J-61d.

26-32. Cythereis? zygoventralis Swain and Peterson, n. sp. (p. 14).

26. Exterior of immature left valve, Loc. J-61h, U.S.N.M. 116684.

27. Right side of holotype, a male, Loc. J-61J, U.S.N.M. 116685.

28. Interior of paratype left valve partly filled with matrix, Loc. J-61J, U.S.N.M. 116686.

29. Right side of female paratype, Loc. J-61J, U.S.N.M. 116687. 

30-32. Right valve interior, dorsal view and left valve interior of three paratypes. All X55. U.S.N.M. 116688-116690.