RISSOID AB. 271 
Animal (of ZL. lapidum). Foot large, longer than the shell; 
tentacles short, rather tapering and pointed. 
BENEDICTIA, Dybowski. Shell Paludiniform, very thin. Oper- 
culum spiral, corneous. Distr—3 sp. Lake Baikal. L. Batk- 
alensis, Gerst. (1xxili, 82). 
JULLIENIA, Crosse and Fischer. Peristome expanded. Cam- 
bodia. JZ. Jullieni, Desh. (1xxiii, 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 anteriorly. Oper- 
culum thin, corneous, regularly ovate. 
Rostrum rather bro ad; 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. 
Somaroeyrus, Gill. 
Distr.—Fresh water, central parts of the United States. 8. 
depressus, Tryon (Ixxiii, 85). 
Shell rather large, globular, thin, smooth, perforate, spire 
small, suture impressed, pody-whor! globose, more or less 
shouldered above; aperture large, oblique, rhombovate, nar- 
rowly rounded in front and back; peritreme thin and acute, its 
entire margin uniformly in one plane, the outer lip not projecting 
anteriorly. Operculum rather thick, corneous, subovate, inner 
margin concave above. 
FLUMINICOLA, Stimpson. 
Distr.—Fresh water, Oregon and California. '. Nuttalliana, 
Lea (lxxiii, 86). 
Shell comparatively large, obliquely 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. 
Cocuniopta, Stimpson. 
Distr.—Fresh water, California. C. Rowelli, Tryon (1xxiii, 
87, 88). 
Shell depressedconic ; base concave and carinated ; umbilicus 
large and deep; aperture oblique. Operculum thin, corneous, 
subspiral. Rostrum moderate, tentacles rather long, t apering. 
