1^2 Bryant Wai^ker 



Valvata tricarinata Say. 



This species. is the type (by designation) of the subgenus Tropidina H. 

 and A. Adams, 1858, but as it is based upon the carinated whorls of the 

 typical form and the species varies from ecarinate to tricarinate, it does not 

 seem worthy of recognition. 



Valvata tricarinata basalis Vanatta. 



Valvata tricarinata basalis Vanatta, Naut., XXVIII, 191 5, p. 105, fig. 

 Type locality : Hudson River, N. Y. 



A^alvata tricarinata infracarinata Vanatta. 



Valvata tricarinata infracarinata Vanatta, Naut., XXVIII, 1915, p. 104, fig- 

 Type locality : White Pond, N. J. 



Valvata tricarinata pErconfusa Walker. 



Valvata tricarinata confusa Walker, Naut., XV, 1902, p. 124, fig,' 2, non V. 



confusa West. (1897). 

 Valvata tricarinata perconfusa Walker, Naut., XXXI, 1917, p. 36. 

 Type locality not specified. 



Valvata utahlnsis Call. 



Valvata sincera utahensis Call, Bull. U. S. Geol. Surv., No. 11, 1884, p. 44, 



pi. VI, figs. T-3. 

 Valvata utahensis Call, Pr. Davenport A. N. S., V, 1886, p. 4, pi. I, figs. 1-3. 

 Type locality : Utah Lake, Utah. 



, Family AMNICOLTD^. 



Subfamily BYTHININ^ Stimpson, 1865. 



Genus BYTHINIA Leach, 1818. 



ByThinia pErFECTa Frauenfeld. 



Bythinia pcrfecta Krauenfeld, Verb, der k. k. zool-bot. Ges. Wien, 1862, p. 



II 54; Ibid, 1865, p. 527, pi. IX. 

 Type locality: Columbia, North America. 



Frauenfeld states that as the types are without the opercula, he could 

 not tell whether the species was a Bythinia or an Amnicola. If the locality 

 is correct, it is surely not a Bythinia. It may be a Fbiminicola. 



Bythinia tentaculata (L.). 



This well known European species has been introduced by commerce 

 and has spread from the Pludson west to Lake Michigan. 



