39 



CONCHIFERA. 



FxOIILY CYCLADIDAE, WOODWARR 



CJE.^'US {Sni.KRIi;-^!, ScoroLi. 



spiia?riiim Simile, Say. {S. sulcatuvi, Lam.) Shell 

 oval, truncated at the extremities in young, and 

 rounded in adult specimens ; convex, sub-equipartite :. 

 beaks slightly elevated; surface with conspicuous- 

 concentric wrinkles; epidermis brown or chestnut 

 color. About seven-tenths of an inch long ; height,, 

 one-half inch ; breadth, two-iifths of an inch. 



This species is abundant in Illinois river. The shells- 

 are bluish within. The young shells are of a lighter 

 color, thinner, and show the wrinkles at all ages ; lines- 

 of growth prominent. Animal with simple mantle v 

 foot tongue- shaped. 



8. s'ldcatum, Lam. is the same shell, but must be- 

 considered a synonym, as Say first described it. 



SI>1I.K:RI1J.^I PAUTIMKltM, Say. 



Shell rounded— oval, sub-equipartite ; lowest ante- 

 riorly, somewhat angular behind ; thin and fragile ; 

 valves very convex, minutely wrinkled by lines of 

 ■growth, and obsoletly radiated; light horn color, 

 beaks elevated. Length, nine-twentieths of an inch. 

 Abundant. 



SPlIiKRIi;:^! OCCII>K3iTAI.E, Prime. 



Shell small, oval, thin, fragile ; strifB fine ; beak& 

 small and rounded ; color light yellow ; beaks not 

 prominent. Length, one-third of an inch. Not so- 

 abundant as the preceding species. 



