INDEX OF GENERA, AND SPECIES. 

ACEPHALA, 85. 
Acicula, 54. 
acicula, Miill., 54. 
Alasmodonta, Say, 91. 
arcuata, Barnes, 91. 
edentula, Say, 95- 
marginata, Say, 93. 
Amnicola, Gould and Hald., 79. 
decisa, Hald., 80. 
grana, Say, 8o. 
limosa, Say, 79. 
AMNICOLIDA, 79. 
Anodon, Cuvier, 93. 
edentula, Say, 95. 
fluviatilis, Dill, 93. 
implicata, Say, 93. 
Tryon, Lea, 95. 
undulata, Say, 94. 
Anculosa, Say, 84. 
dissimilis, Say, 84. 
Ancylus, Geoff., 73. 
rivularis, Say, 73- 
tardus, Say, 74. 
Anguispira, Morse, 34. 
alternata, Say, 35. 
AURICULID&, 60. 
BRANCHIFERA, 85. 
Buccinum, Linn., 54. 
acicula, Miill., 54. 
virginicum, Gmel., 84. 
Bulimus, 52. 
lubricoides, Stimp., 52. 
lubricus, Say, 52. 
Bulinus, 68. 
hypnorum, Linn., 68. 
Bythinella, Mogq., Tand., $0. 
Nickliniana, Stimp., 81. 
_Carychium, Gray, 60. 
exiguum, Say, 60. 
CORBICULIDA, 96. 
Cyclas, Burg., 97. 
fabals, Prime, 99. 
partumeium, Say, too. 
rosaceum, Prime, 100. 
securis, Prime, 101. 
similis, Say, 98. 
stamineum, Con., 99. 
striatinum, Lam., 98. 
transversum, Say, 97. 
Cyclostoma, Mont., 55. 
lapidaria, Say, 82. 
marginata, Say, 55. 
tricarinata, Say, 78. 
GASTEROPODA, I5. 
GEOPHILA, 18, 
Goniobasis, Lea, 83. 
virginica, Gmel., 84. 
var. multilineata, Say, 84. 
Gyraulus, Agass., 71. 
albus, Miill., 72. 
deflectus, Say, 71. 
dilatatus, Gould, 72. 
parvus, Say, 72. 
HELICIDé, 24. 
Helicodiscus, Morse, 47. 
lineatus, Say, 48. 
Helisoma, Swain, 69. 
bicarinata, Say, 70. 
trivolvis, Say, 70. 
var. fallax, Hald., 70. 
Helix, Linn., 26. 
albolabris, Say, 26. 
alternata, Say, 33. 
III 
