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- 



FIG. 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, 39.00; 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 



FIG. 136. 



Radula of CAMPELOMA DECISUM Say. (Original.) 

 lj intermediate tooth; 2, 3, lateral teeth. 



C, central tooth; 



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 



