50 NAIADES OF MISSOURI 
Genus XX. CyprRoGENIA (Agassiz) 
48. C. Aberts (Conrad)—(3. c) 
(15). C. Aberti lamarckiana (lea)—(3. c) 
b.—Marsupium with compressed and dilated ovisacs; post ventral 
margin of mantle smooth to papillose; shell generally without disk 
sculpture, sex dimorphism usually very distinct. 
(a)—Inner post-ventral edge of mantles without flap or papillae, 
but slightly lamellate and crenulated; glochidia elliptic and celti- 
form, when normal in shape either extremely large or small. 
Genus XXI. OBOvVARIA (Raf.) 
Sub-Genus (I)—-PSEUDOON (Simpson) 
49. O. (Pseudoon) ellipsis (Lea)—(1. b) 
Genus XXII. NepHRONArIAS (Cross and Fisher) F 
50. N. ligamentina (Lamarck)—(1. b) 
(16). N. ligamentina gibba (Simpson)—(t. c) 
51. N. ellipsiformis (Conrad)—(t1. c) 
(17). N. ellipsiformis venusta (Lea)—(1. c) 
52. WN. Pleastt (Marsh)—(3. c) 
53. N. ozarkensis (Call)—(3. c) 
Genus XXIII. AmyGpALonatAs (Cross and Fisher) 
54. A. donaciformis (Lea)—(1. a) 
55. A. truncata (Raf.)—(1. c) 
Genus XXIV. Puacrova (Raf.) 
56. P. securts (Lea)—(r. b) ‘ 
Genus XXV. LaAsmonos (Raf.) 
57. L. fragilis (Raf.)—(1. a) 
58. L. Simpsonu (Ferriss)—(3. c) 
59. L. leptodon (Raf.) 
Genus XXVI. PROPTERA (Raf.) 
60. P. alata (Say)—(1. a) 
61. P. purpurata (Lamarack)—(3. c) 
62. P. laevissima (Lea)—(1. a) 
63. P.capax (Green)—(t1. b) 
(b)—Inner post-ventral edge of mantle differentiated with papillae 
and flaps; glochidia normal in shape, medium in size. 
Genus XXVII. CaRUNCULINA (Simpson) 
64. C. parva (Barnes)—(t1.b) 
65. C. texensis (Lea)—(1. a) 
66. C. glans (Ilea)—(1. a) 
Genus XXVIII. Eurynia (Raf.) 
Sub-Genus (II). Mricromya (Agassiz) 
67. E. (Micromya) limosa (Conrad)—(3. ¢c) 
68. E. (Micromya) iris (Lea)—(3. ¢) 
69. E. (Micromya) brevicula (Call)—(3. ¢) 
(18). E. (Micromya) brevicula Brittsii (Simpson)—(1. c) 
Sub-Genus (III).) Eurynta (sens. strict.) 
70. E. (Eurynia) subrostrata (Say)—(1. a) 
71. E. (Eurynia) recta (Lamarck)—(1. c) 
