RISSOID^. 271 



Animal (of L. lapidum). Foot large, longer than the shell; 

 tentacles short, rather tapering and pointed. 



BENEDICTIA, Djbowski. Shell Palndiniform, very thin. Oper- 

 culum spiral, corneous. Distr. — 3 sp. Lake Baikal. L. Baik- 

 alensiH, Gerst. dxxiii, 82). 



JULLIENIA, Crosse and Fischer. Peristome expanded. Cam- 

 bodia. L. Jullieni, Desh. (Ixxiii, 83). 



GiLLiA, Stimpson. 



Distr. — Fresh water. Eastern United States. G. altilis, Lea 

 (Ixxiii, 84). 



Shell rather large, subglobular, thin, subperforate, smooth; 

 spire small, suture not impressed ; aperture large, broad-ovate, 

 oblique ; outer lip thin, acute, not projecting anteriorl,y. Oper- 

 culum thin, corneous, regular!}^ ovate. 



Rostrum rather broad ; tentacles tapering, pointed. Ova- 

 capsules hemispherical; each containing a single egg ; deposited 

 singly or in groups, or linear series. Probably a synonym of the 

 next genus. 



SOMATOGTRTJS, Gill, 



Distr. — Fresh water, central parts of the United States. S. 

 depressus, Tryon (Ixxiii, 85). 



Shell rather large, globular, thin, smooth, perforate, spire 

 small, suture impressed, body-whorl globose, more or less 

 shouldered above; aperture large, oblique, rhombovate, nar- 

 rowly rounded in front and back; peritreme thin and acute, its 

 entire margin uniforml^^ in one plane, the outer lip not projecting 

 anteriorl3^ Operculum rather thick, corneous, subovate, inner 

 margin concave above. 



Fluminicola, Stimpson. 



Distr. — Fresh water, Oregon and California. F. Nuttalliana, 

 Lea (Ixxiii, 86). 



Shell comparatively large, obliquelj^ ovate, thick, smooth, im- 

 perforate ; spire moderate, obtuse ; aperture ovate, inner lip 

 flattened, callous, outer lip effuse and projecting anteriorly, so 

 that the peritreme is not continuously in the same plane. Oper- 

 culum corneous. 



Rostrum rather large, tentacles tapering, foot broad. 



CocHLiopiA, Stimpson. 



Distr. — Fresh water, California. G. Eoioelli, Tryon (Ixxiii, 

 8Y, 88). 



Shell depressedconic ; base concave and carinated ; umbilicus 

 large and deep ; aperture oblique. Operculum thin, corneous, 

 subspiral. Rostrum moderate, tentacles rather long, tapering. 



