44 AMNICOLID. 
Family AMNICOLIDZ. 
(Amnicola, Hald., Turbide, p. 4.) 
GENERA. 
A. Shell smooth, 
Shell elongated, perforate, smooth, 
BYTHINELLA. 
Shell turbinate; whorls very convex, umbili- 
cate; aperture round; peristome continu- 
ous, acute, : : ’ . AMNICOLA. 
Shell elongated, perforate, smooth, very con- 
vex ; aperture round; peristome continuous, 
slightly expanded or reflected. Amphibious. 
Animal, foot with lateral sinuses, 
POMATIOPSIS. 
Shell heliciniform, thick; aperture oblique ; 
umbilicus large, with an. angulated margin, 
CocHLIoPaA. 
Shell subglobular, thin; spire short; aperture 
large, half-round ; peristome not continuous ; 
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