316 THE CHICAGO ACADEMY OF SCIENCES. 
pointed, the whorls convex; sutures well marked, sometimes 
bordered by a faint white line; color varying from light yel- 
lowish horn to pale brown; sculpture as in gyvina, the lines being 
very deep and the wrinkled ridges very convex; protoconch 
consisting of one and one-half smooth, rounded, wine-colored 
whorls; aperture oval, rather wide, produced at the anterior 
end, about two-thirds the length of the entire shell; peristome 
thin, thickened within the aperture by a heavy white or 
yellowish-white callus, which shows through the shell very 
plainly; it is never bordered by a color stripe; the callus of 
two or three former peristomes may always be seen on the 
body whorl and sometimes one or two on the spire; columella 
broad, flat, white, a callus spreading over the parietal wall. 
Length, 12.00; width, 8.00; aperture length, 7.50; width, 3.00 mill. (12352.) 
“ 10:50; “7.80; bs a THES FET SS Me (12352.) 
if 10.00; “ 6.00; ‘ y OSS hte eRe ee (12352.) 
Animal: Not differing essentially from gyrina. 
Jaw. Similar to that of gyvina. 
Radula: Similar in form to that of gyrina, but differing & 
in having six large, nearly equal cusps, instead of five, in the 
general absence of small cusps between the larger ones, and 
in the reflection being wider than in gyrina or heterostropha. 
The radula of this species is remarkably uniform in the form 
of the teeth and in the number of the cusps. The central 
tooth and secondary teeth appeared to be the same as in the 
species previously described. 
Distribution: Great Lakes and St. Lawrence River; I[n- 
diana, Illinois, Tennessee, Michigan, and Wisconsin. 
Geological distribution: Pleistocene. 
Habitat: At stations similar to gyrina. 
Remarks: This species has been generally confounded 
with heterostropha, but will at once be separated from that spe- 
cies by the spiral lines; the general form is also different from 
that of any shell found in this area, and the white callus on the 
lip is peculiar. It is a common shell at Hickory Creek, Lock- 
port and Joliet, and has been found more sparingly at Calumet 
Grove, Maywood, and Edgewater. It is more common than 
sayit, but less so than gyrima. The specimens from Hickory 
Creek are quite typical, resembling closely Haldeman’s figures 
(Pl. 4, Figs. 7, 8) in his monograph of fresh-water Mollusca. 
This species is a biannuan. 
