16 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



half that of the whole shell," Thii'ty of the best specimens of this 

 peculiar form, from Plncher Creek and (looseberry Canon, have been 

 examined by Dr. White, who writes that he " cannot satisfactorily 

 identify them with B. Jisjunctus nor with any other published species." 



Still, thc.~e comparatively long-spired fomis, and those with a short 

 ^-.ire which have already been identified with F. Copei are connected 

 by so many intermediate o-radations that the writer is convinced that 

 they cannot l)e separated specifically, and that the former can only be 

 re^-arded as a well-marked but not very constant variety of the latter. 

 The whole of the Physas that have so far been collected from the 

 Canadian Laramie appear to the writer to belong to one variable 

 specie-. If the identification of any of them with P. Copei bo correct, 

 the whole must be considered as varieties of that >2)ecies, and if incorrect 

 the whole of the specimens here descriljed and figured may be 

 designated simply as P. Canadmsis. By whatever name thoy may be 

 called, their extreme variability suggests the idea that BnUnus disjunc- 

 tus and B. atacus of White may also prove to be varietal fijrms of 

 P. Copei. 



A unu.-ually nai-rowform of the variety Canadensis occurs at Pincher 

 Creek, in which the whorls arc so much flattened laterally that the 

 maximum breadth of the shell is considerably less than half its entire 

 length. Such s])ecimens as these, one of which is represented hy figure 

 'yd of Plate 2, approach vci-y nearly in shape to B. atacus, and it is 

 worthy of note that at Pincher Creek they occur associated with 

 undoubted examples of Viviparus prudentius, White, as B. atacus does 

 in the valley of Crow Creek in Xorthern Colorado. 



Judging by the figure in Pictet's " Traite de Paleontologio," and by 

 that in Zittel's "Handbach der Paleontologie," P. Copei, car Canadensis 

 seems to ho rather nearly related to the Fhysa noljilis of ^Michaud, from 

 the French Lower Eocene, but the original description and figures of 

 that species are unfortunately not accessible to the present writer. 



Dr. Paul Fischer* restricts the use of the name Bulinus, Adanson, to 

 a group of shells with very convex whorls and an obtuse apex, and re- 

 moves that genus from the family Physidas on account of its diiierent 

 odontophore. It is in accordance with this view and in spite of its 

 close resemblance to B. disjunctus that the present shell is regarded as a 

 Physa rather than a Bulinus. 



Manuel de Conchyliologie. Vol. I. p. 509. Paris, 1881. 



