96 Cincinnati Society of Natuial History. 



Sub-family Ancylin*:. 

 genus ancylus. 



77. Ancylus rivularis, Say. 



Small scale like narrow at one end. 



78. Ancylus tardus, Say. 

 Same width at both ends. 



OPERCULATA. 



Family Valvatid^. 

 genus valvata. 



79. Valvata tricarinata, Say. 

 W..3-16. Three carina. 



Family Viviparid/e. 

 genus melantho. 



80. Melanthb integra, Siy, 81, 82, 83, 84, 85, 86, 87. 

 H. \y 2 , green. 



81. Melantho decisa, Say. 



A variety of No. 80. Apex eroded. 



82. Melantho ponderosa, Say, 83. 

 Rounder and heavier than No. 80. 



83. Melantho obesa, Lewis. 



Same shape as No. 82, but not so heavy. 



Genus Lioplax. 



84. Lioplax sub-carinata, Say. 



H. y^, light brownish color, carina distinguishes it from No. 80. 



Family Amnicolid^e. 

 genus amnicola. 



85. Amnicola Cincinnatiensis, 86. 

 Like the young of No. 80, minute. 



Genus Somatogyrus. 



86. Somatogyrus integer, 87. 



Like No. 85, but larger, spire shorter and mouth rounder. 



