246 NEW YORK STATE MUSEUM 



hinge margin narrow, cardinal teeth very small or rudimentary, one 

 of them more or less bifurcated, one cardinal tooth in the right and 

 two oblique ones in the left valve; lateral teeth compressed and 

 lamelliform, the anterior shortest; ligament short; margins plain; 

 muscular impressions scarcely apparent and pallial line simple. 



Sphaerium striatinum (Lam.) Prime 1865 (Fig. 



|. 177). Cyclas striatina Lamarck (1818. 



■ } Animaux sans vertebres, 5 :56o). Sphaerium 



X striatinum Prime (1865. Smith. Misc. coll. 



I ."" ■;;; no. 145, p. 37) 



v ^ Shell slight, moderately elongated, somewhat 



compressed, and inequilateral; anterior margin 



Fig. 177 sphaerium stnati- rounded; beaks full, not much raised and not 



sculptured; sulcations slight and irregular; hinge 



line curved; cardinal teeth small, double, and of the same size; 



lateral teeth larger, but not very prominent. 



Localities. Found in all the deposits on Goat island, Foster's 

 flats, etc. 



This little bivalve is very common in the river at the present time. 

 It is not difficult to understand how these shells were deposited, if 

 one studies the life and habits of the recent forms. The streamlets 

 passing among the rocks that form the Dufferin islands will be 

 found to contain hundreds of these small shells. The bottoms of 

 the pools formed by eddies are white with the accumulation of dead 

 shells, in such quantities that they may be taken up by the shovelful. 



Sphaerium stamineum (Conr.) Prime 1865 (Fig. 178). Cyclas 

 s t a m i n e a Conrad (1834. Am. jour. 25 :342). Sphaerium 

 stamineum Prime (1865. Smith. Misc. coll. no. 145, p. 38) 



Shell oval, full and inequilateral; anterior end y^^^-iS 



abrupt; posterior end somewhat distended; beaks /'" -^ §\ 



full, prominent and sometimes sculptured; striae > :: . , ! 



heavier than in the foregoing species; hinge mar- fM 



gin more curved; cardinal teeth double, and not V ;J 



very distinct; lateral teeth stronger. --—__._.--' 



In this, as in the preceding species, specimenSgtammJum. x^ haerium 

 frequently occur in which the hinge is reversed. 



Localities. Goat island, Prospect park, and near the Whirlpool. 



Recent species of this interesting group of fresh-water bivalves 

 abound in Niagara river and its tributaries. While they prefer the 

 soft mud at the bottom, they are frequently found attached to the 



