132 Bryant Walker 



Valvata tricarinata Say. 



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

 and A. Adams, 185S, 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 r.ASALis Vanatta. 



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

 Type locality : Hudson River, N. Y. 



Yma'ata tricarinata tnfracarinata Vanatta. 



J^ak'ata tricarinata infracarinata Vanatta, Naut., XXVIII, 1915, p. 104, fig. 

 Type locality : White Pond, N. J. 



Valvata tricarinata plrconfusa Walker. 



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



confusa West. (1897). 

 J'alvata tricarinata perconfnsa Walker, Naut., XXXI, 1917. p. 36. 

 Type locality not specified. 



Valvata utahknsis Call. 



J'ak'ata sinccra ntahcnsis Call, Bull. U. S. Geol. Surv.. No. 11, 1884, p. 44, 



pi. VI, figs. T-3. 

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

 Type locaHty : Utah Lake, Utah. 



Family AMNICOLID.^. 



vSul)family BYTHININ^E Stimpson, 1865. 



Genus BYTHINIA Leach, 1818. 



BvTHiNiA pLrFECTa Frauenfeld. 



Bythinia pcrfecta Frauenfeld, 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 Flmninicola. 



Bythinia tkntaculata (L.). 



This well known European species has been introduced by commerce 

 and has spread from the Hudson west to Lake Michigan. 



