VALVATA SINCERA. 



OBSERVATIONS. 



When the posterior margin of the aperture 

 is anterior to the medial carina, the spire be- 

 comes bicarinate. 



The animal sometimes moves along in an 

 inverted position, with the foot applied to the 

 surface of the water. 



The ova are deposited from the first day of 

 March to the end of July, in transparent masses 

 half a line in diameter, each containing a num- 

 ber of germs of a bright green color, dotted 

 with yellow. 



VALVATA SINCERA, Say. 



PLATE 1'. FIG. 



V. testa globoso-discoidea, tenui, virescente, late per- 

 forata, spira subelevata, anfractibus 3 4 simplicibus. 



SYNONYMS AND REFERENCES. 



V. SINCERA, SAY. Long's 2nd Expedition, Appendix. 

 V. SINCERA, ADAMS. App. Hist, of Vermont, p. 2. 



