40 ■ VALVATA. 



Family VALVATIDuE. 



Genus VALVATA, 0. F. Midler. 



For description of genus, see Haldeman's 

 Monog., p. 1. 



1. VALVATA TRICARINATA, Say. 

 Hald., p. 3, t. i, figs. 1—4. 



Inhabits from New England to Virginia, and 

 westward to Iowa. Great Slave Lake. 



In favorable localities this species attains a 

 much greater size than the figures indicate. 



2. VALVATA SINCERA, Say. 

 Hald., p. 6, t. i, f. 6—10. 



Inhabits from Vermont to Pennsylvania, 

 and westward to Iowa. Mackenzie's River, 

 Great Slave Lake. I scarcely think this dis- 

 tinct from the above, the degree of carination 

 varying so greatly. It must be regarded as a 



doubtful species. 



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