360 THE CHICAGO ACADEMY OF SCIENCES. 
rather long and tapering, the eyes situated on the outside on 
an enlargement of the tentacles one-third the distance be- 
tween the base and tip; in the male the right tentacle is modi- 
Fic. 135. 
Animal of CAMPELOMA DECISUM Say. Female. (Binney, Fig. 68.) 
fied to form the verge; foot very large, broad, produced in 
front, and much in advance of the head and tentacles. Length 
of foot, 39.co; width, 19.00 mill. Foot truncated in front and 
slightly auriculated, rounded behind, translucent (Fig. 135). 
Operculum longer than wide, convex, subconcentric, with the 
nucleus near the left margin; dark reddish brown in color. 
Length, 11.00; width, 6.00 mill. 
Radula formula: 3-1-3, central tooth very broad, the 
lower corners of the base of attachment attenuated; reflection 
simply hooked, without denticulations; intermediate tooth 
a 3 
Fic. 136. 
Radula of CAMPELOMA DEcISUM Say. (Original.) C, central tooth; 
1, intermediate tooth; 2, 3, lateral teeth. 
similar to central, but narrower; second and third lateral teeth 
very long and narrow, somewhat fang-shaped, simple (Fig. 136). 
Distribution: Massachusetts to Illinois and Minnesota, 
south to Tennessee and Virginia. In British America from 
Nova Scotia to Saskatchewan River. 
Geological distribution: Pleistocene; Loess. 
Habitat: Found generally on a muddy bottom almost 
