326 THE CHICAGO ACADEMY OF SCIENCES. 
tinged with blue or purple, and reflected over the columellar 
region and columellar lip; last whorl usually very convex, in- 
clined to bulbous. Operculum not essentially different from 
that of Pleurocera. 
Length, 16.50; width, 7.00: aperture length, 6.50; width, 3.50 mill. (8748.) 
« 18.00; “7.50; 7.00; “ 400 “ (8748) 
“12.00; “ 600; « “  6.00;° * 3.00 “ (8748) 
“11.00; « 600; « “600; “ 350 “ (8748) 
« 13.00; “ 6.00; « “550; * 300 “ (8748) 
“15.50; “ 700; « “700; « 400 “ (8746) 
« 90.00; «© 950; “900; “ 5,00 “  (12869.) 
Animal: Similar to Pleurocera in form; color bluish- white 
on base of foot and sides; body yellowish, darker in places; 
rostrum blackish on middle portion, yellowish at the tip; neck 
yellowish; the rostrum is not as heavy as in the last genus. 
There seems to be little generic difference between the animals 
of these two genera. 
Faw: Like that of Pleurocera. 
Radula formula: ys +4+44+4+44+44+4 (3—I1—3); the 
teeth are similar to those of Pleurocera subulare, excepting that 
the central tooth has four small cusps on each side of the cen- 
tral cusp; the cusps are a little rounder in the present species 
than in the one mentioned. 
Genitalia: Not observed. 
Distribution: New York to Great Lakes, south to Ohio 
River drainage. 
Geological distribution: Pleistocene; Loess. 
Habitat: Found rather plentifully on a muddy (some- 
times sandy) bottom, in water from two to tenor more feet in 
depth. Prefers a bottom with water weeds. 
Remarks: A very distant species, at once known by its 
bulbous form, convex outer lip and bluish or purplish aperture 
and columella. The spire is very broadly conic. G. milesiz is 
simply a smooth, extra bulbous form of /vescens, not entitled 
to even varietal rank. There is considerable variation in the 
carination of the upper whorls, but all of these different forms 
may be connected with the type by aseries of specimens. The 
individuals from Lake Michigan are always heavier and more 
solid than those from the smaller lakes and rivers. 
The animal moves slowly, pushing its foot forward a short 
distance and then drawing the shell after it. This is particu- 
larly noticeable when crawling up the side of a glass jar. 
