48 NON-MARINE FOSSIL MOLLUSCA. 



as Helix vetusta, and the other under the name of Tkaumastus limncefor- 

 mis;* the first being represented on Plate 27 and the latter on Plate 25. 

 The former is perhaps not a typical Helix, but the latter is probably a 

 true representative of Thaumastus, as that genus is known among living 

 mollusca. If so, it is the only fossil representative of the section of 

 the Helicidae to which it belongs that is at present known in North 

 America strata (if we except the Bulinus floridamus of Conrad from the 

 Eocene of Florida and perhaps also the species mentioned on page 39 

 under the name of Limnwa(Limnophysaf) compactilis, although living 

 species of Thaumastus are not uncommon in the southern part of North 

 America. 



From the Fort Union Laramie beds of the Upper Missouri River region 

 Meek & Hayden also described two species of Helicidae under the 

 names respectively of Golumna teres and G. vcrmicula.i These also are the 

 only representatives of their genus that are yet known in North Ameri- 

 can strata, and, like the next preceding species, no living congeners are 

 found in North America so far northward as the localities from which 

 the fossil species were obtained. Both these forms are represented on 

 Plate 25. 



From the Laramie strata of Southern Utah Professor Powell obtained 

 a species of Helix that seems to possess the characteristics of the sub- 

 genus Strobila Morse, and which I have described under the name of 

 Helix lMnabensis.\ It is figured on Plate 25. It was found associated 

 with Physa kanabensis and Planorbis (Bathyomphalus) Mnabensis, both 

 of which have already been noticed. 



A series of coal bearing strata near Evanston, Southwestern Wyoming, 

 which apparently belong to the upper part of the Laramie Group, have 

 furnished a number of species of pulmonate mollusca, among which 

 are two species of Helix, namely H. Sepulta and H. evanstonensis White.§ 

 The former seems to possess the subgeneric characteristics of Patiila 

 Haldeman, and although its characteristics have been quite clearly 

 ascertained, the specimens are all too imperfect for figuring. H. evans- 

 tonensis is apparently referable to the subgenus Trioclopsis Rafinesque. 

 It is figured on Plate 27. 



From the Wind River Group, a series of fresh-water Eocene strata in 

 Western Wyoming, a flue species was obtained by Meek & Hayden 

 and described by them under the name of Helix? veterna.\\ It is repre- 

 sented by copies of Mr. Meek's figures on Plate 30. Certain charac- 

 teristics presented by this shell cause some doubts to arise as to its real 



* For figures and descriptions of both these species see U. S. Geol. Sur. Terr., vol. 

 ix., pp. 552, 553, pi. 42, fig. 7; and pi. 44, fig. 8. 



tU. S. Geol. Sur. Terr., vol. ix, pp. 555, 556, pi. 44, figs. 11 and 12. 



t Powell's Rep. Geology of Uinta Mountains, p. 120. 



ft The first of these species was originally described in Proc. U. S. Nat. Musoum, 

 vol. iii, p. ICO; and the other in Bull U. S. Geol. Sur. Terr., vol. iv, p. 714. 



|| U. S. Geol. Sur. Terr., vol. ix,p. 596, pi. 42, fig. 8. 



