CONCHOLOGIA CESTRICA. 79 



Family AMNICOLID^E. 



Shell, turbinate, or elongate-turreted, smooth, perfo- 

 rate, or umbilicate ; peristome continuous ; shell often 

 covered with blackish incrustations. 



Animal, head proboscidiform, extending beyond the 

 foot ; tentacles cylindrical, elongated ; eyes sessile at 

 their outer bases ; foot oval, truncated in front, and 

 rounded, or pointed, behind; verge exserted, behind 

 the right tentacle ; operculum corneous, sub-spiral. 



Genus AMNICOLA, GOULD, and HALDEMAN, 1840. 



Animal of A. limosa, enlarged. [Stimpson.] 

 Fig, 164, 



Shell, small, sub-ovate, thin, smooth, perforate; spire 

 short; aperture broad- ovate; peristome continuous. 



Animal, foot short, broad, expanded, and rounded, 

 behind, auricled in front ; rostrum short ; tentacles 

 cylindrical, blunt; verge bifid, with a globular base; 

 opercle thin, sub-spiral. 



A. limosa, SAY. 



Paludina limosa, Say, Jour. Acad. Phila., L, A ^ 1 ' 

 1817. Tig, 165,' 



Shell, conic, sub - umbilicate, dark horn 

 color; epidermis wrinkled; aperture ovate- 

 orbicular ; suture impressed. H. 3, W. 2, mill. 



