THE NATURAL HISTORY SURVEY. 345 
the mouth on the lower side; tentacles short, pointed, taper- 
ing, carried resting by the side or base of the rostrum, never 
elevated as in the pulmonates; eyes situated on the outer side 
of swellings at the base of the tentacles; verge very large, sit- 
Fig. 127. 
Animal of POMATIOPSIS LAPIDARIA Say. (Binney, Fig. 187.) 
uated in the middle of the back, some distance behind the 
head, coiled one and one-half times, end pointed, outer margin 
smooth, inner margin wrinkled (Fig. 127). Operculum thin, 
horny, subspiral, not differing materially from Azunicola imosa 
Say. 
Radula formula: 44+4+44+535+444+44 (3—1-—3); central 
or rhachidian tooth as broad as high, tridentate, denticles on 
base of attachment two on each side, directed inward; inter- 
al 
Fic. 128. 
Radula of POMATIOPSIS LAPIDARIA Say. (From Nature, after Stimp- 
son.) C, central tooth; 1, intermediate tooth; 2, 3, lateral teeth. 
mediate tooth longer than wide, four-denticulate; lateral teeth 
narrower than intermediate, five-denticulate the denticulations 
subequal (Fig. 128). 
Distribution: New York to Iowa, Michigan to Missouri and 
Georgia. 
Geological distribution: Pleistocene; Loess. 
Habitat: Living in fresh water or on land (amphibious), 
frequenting, when in water, the vicinity of fresh-water plants; 
