52 VALVATA. 



Valvata sincera, Say — Shell subglobose-conic ; whirls nearly four, 



accurately rounded, finely and regularly wrinkled across ; 



Fig. 88. 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 



V sincera ^^^S^> 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. {Say.) 



Valvata sincera, Sat, Long's Ex. 264, pi. xv, f. 11 ; Binney'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.— DeKay, N. Y. Moll. 119, pi. vi, f. 127, 

 128. 

 Valvata depressa, pars, Kijster in Chemn. ed. 2, p. 88 (1852). 

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



The outline figure published by Say and copied in my figure 88 

 is not very satisfactory, nor have I ever seen specimens referred to 

 this species which can easily be distinguished from ecarinate forms 

 of V. tricarinata. Fig. 83 is a view of the animal copied from 

 Haldeman. 



I give also a figure of a specimen of V. striata furnished by 

 Dr. Lewis. I have no doubt of its identity with V. sincera. Dr. 

 Lewis' description is as follows : — 



Fig. 89. Valvata striata. — Shell conical, depressed, umbilicate ; aper- 



ture round ; epidermis brown and very regularly striate. Has 

 all the other features of sincera except color and translucency. 



V. striata. Animal not observed. Very rarely seen. Of several hundred 

 specimens of Valvata only seven were this species. {Lewis.) 



No. 8936 of the collection was labelled V. sincera by Dr. R. 

 E. Griffith. 



Valvata piipoidea, Gould — Shell small, elongate-ovate, opaque, 



chestnut-colored, when divested of the rough, dirty pigment which usually 



adheres closely to it; whirls four or five, minutely 



Fig. 90. wrinkled, the posterior one small and flattened so as 



c_4 to form an obtuse apex ; the others cylindrical, and so 



partially in contact as to expose about one-half of the 



cylinder ; the last entirely disjoined from the preceding 



j one for at least the half of a revolution ; aperture cir- 



Valvaiapupoidea. ^ular, lip simple and sharp; on looking at the shell 



from below, no umbilical opening is found ; operculum 



horny, apex central, elements concentric. Length .1, breadth 3-40 inch. 



