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THE NATURAL HISTORY SURVEY. 341 
two; intermediate tooth similar to that of zfeger, excepting 
that the perforation has a little lid or door which hangs below 
the basc of attachment; lateral teeth as usual, with about 
twelve denticles, those of the first tooth larger than those of the 
second (Fig. 124). (Stimpson.) 
Distribution; Ohio Valley; Ohio to Iowa, Michigan and 
Wisconsin south to Kentucky. ; 
Geological distribution: Pleistocene. 
Habitat: Found in small ponds, ditches, sloughs and riv- 
ers where there is a muddy or clay bottom. 
Remarks: This is the largest species of the genus found 
in the area under consideration; this fact, together with its 
subglobose form, will distinguish it. It is three or four times 
Fia. 124. 
Radula of SOMATOGYRUS SUBGLOBOSUS Say. (Stimpson, Hydrobiinz, 
Fig. 14.) C, central tooth; 1, intermediate teeth; 2, 3, lateral teeth. 
the size of S. integer. Subglobosus is fairly common and has 
been found by Messrs. Ferriss and Jensen, the former at Joliet 
and the latter on the lake shore and in George Lake. The 
animal has not been observed. The spire of the shell varies 
considerably in height, some being much more elevated than 
shown in the figure. 
It has been found fossil by Mr. Jensen in sand banks on 
the lake shore north of Graceland avenue. 
140. Somatogyrus integer Say, pl. xxvi, fig. 2. 
Melania integra SAy, New Harm. Diss., Vol. II, p. 276, 1840. 
Amnicola depressa TRYON, Proc. Phil. Acad., p. 452, 1862. (Variety.) 
Shell; Orbicular, solid, depressed; color subhyaline, some- 
times inclining to dark horn; surface shining, lines of growth 
oblique, fine, numerous, crowded, somewhat raised; sutures 
rather deeply impressed; apex small, rounded; aperture roundly 
ovate, somewhat produced at the lower part, subhyaline in- 
side; spire short, rounded; whorls four, convex, the last swol- 
