Synopsis Fre:sh-Wate;r Moi,i,usca 31 



Key to the genera of Lithoglyphincc. 

 r Shell imperforate or narrowly perforate 2. 



'•1 . • 



1^ Shell widely umbilicate -^. 



f Peritreme sinuous, lip effuse below, verge winged Flnininicola. 



2. \ Peritreme continuous in same plane, verge simple Gillia. 



[ Peritreme very oblique, lip effuse above^ verge bifid. . . .Soinatog\nts. 



f Shell spirally striate, depressed, turbinate, widely umbilicate 



3. j CocJiliopa. 



[ Shell smooth, globose-turbinate, umbilicus narrower, but deep. Clappia. 



Genus COCHLTOPA Stimpson, 1865. 



^ Shell depressed-conic; base concave, umbilicus large and 



>;^?^^^^^ deep; aperture oblique; operculum corneous, subspiral. 



V^vsL\^^^ Rostrum of moderate size; tentacles rather long and tap- 



^^^:;^|^ J ering. Teeth of the radula multicuspid, basal denticles on 



■p..^^^^— ^ central tooth 2 or 3 on each side. Verge rather elongated, 



^'^ compressed, geniculated and bifid. 



Tyije : .hmiicola rowelUi Tryon. 



Example: C . riograndcnsis P. and F., fig. 106. 



Genus CLAPPIA Walker, 1909. 



Shell minute, spiral, dextral, globose-tur- 

 binate, narrowly but deeply umbilicate. Spire 

 A\V iiiliHk short; body whorl large; whorls round; aper- 



ture large ; lip simple ; columellar lip thin, ap- ji^, 

 pressed to the body-whorl only at the upper (Cf.^ 

 end; operculum paucispiral, nuclear whorls 

 large, slowly and regularly increasing. P'ig. 108 



Fig. 107 Rachidian tooth as in Somatogynis, in- 



termediate tooth with a long peduncle and a strong tooth projecting from 

 the infero-anterior angle, laterals multicuspid. 



Fig. 109 

 Type: C. clappii Walker, fig. 107. Operculum, fig. 108. Radula, fig. 109. 



