32 



Bryant Wai^kkr 



Fig. no 



Fisf. Ill 



Genus FLUMINICOLA Stimpson, 1865. 



Shell spiral, dextral, 

 obliquely ovate, thick, 

 solid, smooth, imperfor- 

 ate; spire moderate, ob- 

 tuse ; aperture ovate ; 

 columella flattened, cal- 

 loused ; lip efi^use and 



projecting anteriorly so that the peritreme is not continuously in the same 



plane ; operculum corneous, subspiral. 



Rostrum rather large; tentacles tapering, foot broad; central tooth of the 



radula with several basal denticles on each side ; outer lateral teeth with a 



smaller number of denticles than the inner. Verge large, compressed, with 



a broad semicircular wing on the left side. 



Type: Paludina mittaUiana Lea, fig. no. Radula, fig. in. 



Genus SOMATOGYRUS Gill, 1863. 



Shell dextral, spiral, usually rather thick and solid, smooth, imperforate 

 or narrowly perforate ; spire usually short ; apical whorl spirally punctate 

 or lirate ; body- whorl large, more or less inflated ; aperture very oblique ; lip 

 sharp, projecting above; columella callously thickened. Operculum corne- 

 ous, subspiral, nuclear whorls small, rapidly increasing. 



Fig. 112 Fig. 113 Fig. 114, 



Rostrum rather broad, flat and square-cut ; tentacles rather short and 

 flattened ; teeth of the radula multicuspid, basal denticles on the central tooth 

 3-4 on each side. Verge broad, compressed and bifid. 



Type: Amnicola dcpressa Tryon, fig. 112. Radula, fig. 113. Operculum, 

 fig. 114. 



Genus GILLIA Stimpson, 1865. 



Shell spiral, dextral, not 

 very thick, smooth, imperfor- 

 ate ; spire short, obtuse, body 

 whorl large, inflated ; aperture 

 large, oblique ; peritreme con- 

 tinuous on the same plane, lip 

 thin, sharp ; columella very 

 slightly thickened ; operculum corneous, subspiral. 



Rostrum broad, subtruncate, foot oblong, rounded behind and auriculate 



