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THE OTTAWA pTORAUSt 



sP- 



Vol. XV. 



OTTAWA, JUNE, 1901. 



No. 3. 



NOTES ON A TURTLE FROM THE CRETACEOUS ROCKS 



OF ALBERTA.* 



By Lawrence RI. Lambe, F. G.S., of the Gt'olog:ical Survey of Canada. 



{With four plates.) 



In the collection of reptilian remains, made by the writer 

 during^ the summers of i8q7 and 1898, from the Cretaceous of the 

 Red Deer River, Alberta, are parts of two plastrons of a Chelonian, 

 of large size, that evidently belong to Cope's species Compsemys 

 variolosus. The specimens are in an excellent state of preserva- 

 tion and throw new light on the generic affinities of the species. 

 Referable also to this species are parts of the carapace, plastron 

 and endoskeleton, belonging presumably to one individual, that 

 were collected in 1881 by Dr. G.M. Dawson on the Old Man River 

 below Fort McLeod, and two marginal bones with some smaller 

 fragments of the shell obtained by Mr. R. G. McConnell on the 

 Red Deer River in 1882. These latter specimens, taken in con- 

 junction with those first mentioned, form a most interesting series 

 that help to elucidate some important structural points. 



The rocks exposed on the Red Deer River, from which the 



[specimens of Mr. McConnell and the writer were obtained, belong 



[to the Belly River series which underlies the marine Pierre-Fox 

 Hills (or Montana) formation in this region. The specimens col- 



ilected by Dr. Dawson on the Old Man River are from a higher 

 horizon, viz., the Willow Creek subdivision of the Laramie. 



The original description of C. variolosus, Cope, based on 



■ material from the Fort Union (Laramie) beds of Montana, ap- 



*Communicated by permission of the Director of the Geological Survey 

 "of Canada. 



