108 ON THE LAND AND FRESH-WATER 



Figure 2. 

 Sphcerium soliduhim, Prime. 



Animal not observed. 



Shell transversely inequilateral, elongated, slightly convex; beaks 

 full, not very prominent; anterior margin rounded; posterior 

 drawn out to an angle ; base slightly curved : epidermis variable, 

 dark chestnut or brownish yellow, with sometimes a yellow zone on 

 the basal margin ; sulcations coarse, irregular ; interior dark blue ; 

 hinge margin considerably curved ; cardinal teeth double, in the 

 shape of tbe letter V reversed ; lateral teeth large ; the anterior 

 placed at an angle with the margin ; the posterior more on a con- 

 tinuation of the curve. 



Long. 9-16 ; lat. ,7-16 ; diam. 5-16 inches. 



Differs from the preceding species in being less elongated, more 

 inequilateral, less convex ; the hinge margin is more curved, and 

 the shell is more solid than in the S. sulcatum. Having unfortu- 

 nately mislaid my only specimen from L'Orignal, the figure is 

 taken from a fine large specimen from the Little Miami river, at 

 Waynesville, Ohio. Canadian specimens will probably be smaller, 

 and with their distinctive characters less strongly marked. 



<<#!>H^ /^^~\>. 



U 



Figure 3. 

 Sphcerhtm striatinum, Lamarck. 



Animal white ; tubes light reddish yellow. 



Shell slight, transversely elongated, somewhat compressed, ine- 

 quilateral ; anterior margin rounded, posterior distended, inferior 

 rounded; beaks full, not much raised ; sulcations irregular, at times 

 so light as hardly to be seen with the naked eye, thus giving the 

 shell a lustrous appearance ; colour varying from a light greenish- 

 yellow to a darker shade ; valves slight ; interior blue ; hinge margin 



