FAMILY VALVATID.4: 121 



crate number of whorls slowly enlarging anJ without spiral keels. 

 Type V. piscinalis (Miiller). 



lelskia Bourguignat {Jclskta West., not Tacz.). Shell turbinate, 

 with few rapidly enlarging whorls and no spiral keels. Type V. 

 jelskii Crosse. 



Tropidina H. and A. Adams. Shell depressed turbinate, with the 

 upper surface of the spire more or less flattened and the whorls spi- 

 rally keeled. Type V. tricarinata (Lesueur) Say. 



Since Miiller associated but one species with the genus when de- 

 scribed, that species necessarily becomes the type. A failure to rec- 

 ognize this, when subdividing the genus, is responsible for several of 

 the synonyms. I have not been able to consult Iliibner's Zwei IJriefe, 

 and cite him on the authority of Westerlund, but, judging by his paper 

 on Cobresia of the same year, his nomenclature was not Linnean, 

 although his artistic capacity seems to have been exceptional. 



Valvata tricarinata Say. 



Cychstoma tricarinata Say, Journ. Acad. Nat. Sci. Phila., i, p. 13, 18 17. 

 Valvata tricarinata Say, op. cit., 11, p. 173. 1821. — Gould, Inv. Mass., 

 p. 225, fig. 156, three views, 1841.— Haldf.man, Mon. Limn., viii, p. 

 3, pi. I, figs. 1-4, 1845. 

 Valvata carinata Sowerbv, Genera, part XLi, fig. 2, 1834. 

 Valvata unkarinata De Kay, Zool. N. V., Moll., p. ilS, pi. vi, fig. 129, 1843. 

 Valvata tricarinata \^x. simplex GoULD, Inv. Mass., p. 226, fig. 156 (right 



hand figure), 1841. 

 Valvata htimeralis Miles, Geol. Surv. Michigan, p. 237, i860, not of Say. 

 Valvata tricarinata var. confusa Bryant Walker, Nautilus, xv, No. 11, p. 

 124, fig. 2, 1902. 



Range, — From New England and Virginia westward to the Mis- 

 souri, and northward. 



Type : St. Lawrence River and the Great Lakes ! Manitolia, in 

 Great Playgreen and Winnipeg Lakes ! and Pine Creek ; Red Deer, 

 Alberta ; Moose Factory, Keewatin ; Saskatchewan 

 River ! Great Slave Lake ! Methy Lake in Lat. 57° N. ^_ 



Variety simplex: English River, Keewatin! ^^O 



Peace River, Athabaska ! Great Slave Lake, at Fort 

 Resolution! upper Mackenzie River at Fort Simp- ^ ' ■.' . 

 son ! in N. Lat. 62°. („^ |. 



Full grown specimens of this species liave three 

 and a half whorls, a maximum diameter of 5, and an altitude of 3 

 mm. This applies to both varieties, though under exceptionally 

 favorable circumstances it may be somewhat exceeded. The aper- 

 ture is orbicular and almost vertical in plane. 



