44 NON-MARINE FOSSIL MOLLUSC A. 



souri Eiver region, and which I described under the name of Pliysa 

 copei.* 



Some fragments of a Physa have been found in the Laramie strata of 

 Crow Creek Valley in Colorado, east of the Bocky Mountains, that indi- 

 cate a somewhat remarkable aud interesting form. It was described by 

 me under the name of Physa felix. t The best example yet discovered 

 is figured on Plate 25. 



A species which occurs iu the Wahsatch Group of Eocene strata in 

 Southern Wyoming and adjacent parts of Colorado and Utah, and 

 which reaches a greater size than any other known fossil Physa, perhaps 

 excepting P. copei, has been described by myself under the name of P. 

 pleromatis.% The type specimen of the species is figured on Plate 30. 

 Some imperfect specimens have been found in Colorado, apparently be- 

 longing to this species, that indicate a very much greater size. A par- 

 tially restored figure of one of these is given on Plate 30. 



Another fine species has been described by Meek from the Bridger 

 Eocene group of Southern Wyoming, under the name of Physa bridger- 

 ensis.§ It is illustrated on Plate 30. 



Physa pleromatis is apparently a typical Physa, but P. bridgerensis 

 perhaps ought to be referred to Bulinus. For present convenience, 

 however, it is referred to Physa. 



From the Miocene White Eiver Group of Dakota, Evans & Shuinard 

 described Physa secalina,\\ which is represented on Plate 32. It has a 

 very modern aspect, although it is regarded as an extinct species. No 

 fossil Physa of later age than this has yet been published from any 

 North American strata, but one or more species is known to exist in 

 certain strata of Southern Wyoming aud North western Colorado, which 

 Professor Powell has named the Brown's Park Group, and are probably 

 of Pliocene age. 



The genus Bulinus is well represented iu the Laramie Group, but no 

 other species of that genus has yet been published from any other Noith 

 American strata, unless Physa bridgerensls should prove to be a Bulinus, 

 as already suggested. Associated with Physa copei in the Judith Biver 

 Laramie beds, Professor Cope found a fine large species of Bulinus which 

 I described under the name of B. atavus.^\ It is figured on Plate 25. 



From the Laramie strata, at the mouth of Judith Biver, Meek & 

 Hayden obtained the type specimens of Bulinus subelongatus ;** which 

 is represented on Plate 25. 



From the Fort Union Laramie beds two other specimens of Bulinus 



*Au. Rep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 84, pi. 22, fig. 1. 



tAn. Rep. TJ. S. Geol. Sur. Terr, for 1878, Part I, p. 84, pi. 22, fig. 1. 



X Expl. and Sur. West of tlie 100th Merid., vol. iv, p. 211 ; pi. xxi, fig. 1. 



§ An. Rep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 45, pi. 19, fig. 10. 



|| U. S. Geol. Sur. Terr. vol. ix, p. 004, pi. 45, fig. 4. 



IT An. Rep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 86, pi. 24, fig. 5. 



*"" U. S. Geol. Sur. Terr., vol. ix, p. 540, pi. 42, fig. 13. 



