12 



LAND AND FRESH-WATER SHELLS OF N. A. [PART III. 



These dimensions are from one of the largest size, obtained from Lake. 

 Champlain, where they are very abundant, and from the Erie Canal. It is 

 allied to the preceding ( V. tricarinata), and forms the passage to V. sincera. 

 Some eminent conchologists suppose this, and perhaps the following ( V. 

 sincera) to be mere varieties of 1'. tricarinata. It approaches the V, hume- 

 ralis, Say, from Mexico ; but it is smaller, not so much depressed, and has 

 a wider umbilicus. {DeKay.') 



I have evidence of its ranging at least from New England and 

 Pennsylvania to Council Bluff and Alethy Lake, lat. 57°. 



Haldeman says 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 number of germs of a bright green 

 color dotted with yellow. 



V. sincera. 



ValTata sincera, Sat. — Shell subglobose-conic ; whirls nearly four, 



accurately rounded, finely and regularly wrinkled across ; 



Fig. 17. aperture not interrupted by the penultimate whirl, nor ap- 



pressed to it, but merely in contact with it, the labrum not 



diminished in thickness at the point of contact ; umbilicus 



large, exhibiting the volutions. Breadth less than 1-5 inch. 



Inhabits Northwest Territory. 



For this species I am indebted to Dr. Bigsby. It is very similar to the 



tricarinata, Nobis, but it is destitute of carinated lines and the umbilicus 



is rather larger ; it differs from the ohtusa of Europe also, in the much 



greater magnitude of the umbilicus. CSay.) 



Valvata sincera, Sat, Long's Ex. 264, pi. xv, f. 11 ; Bixnet's ed. p. 130, 



pi. Ixxiv, f. 11.— Haldeman, Mon. p. 6, pi. i, f. 5-10.— Adams, Sh. 



of Vt. in Thorns. Vt. p. 152; Am. Jour. Sc. [i], XL, 267.— DeKat 



N. Y. Moll. 119, pi. vi, f. 127, 128. 

 Valvata depressn, pars, KtfsTER in Chemn. ed. 2, p. 88 (1852).— Mexke. 



Zeit. fiir Mai. II, 122, 1845 (including tricarinata and simplex'). 

 Valvata striata, Lewis, Pr. Phil. Ac. N. Sc. 1856, p. 260. 



