46 



This species, the type of the genus, is represented by a large number of vertebrae, 

 none of which were found together in their proper relative positions, but in a few in- 

 stances, a number, collected within limited areas, may represent incomplete series. 



The vertebrae consist of cervicals, dorsals, caudals and some from the sacral region. 

 The anterior dorsals are keeled below, in the dorsal series the angularity gives way to a 

 rounded lower surface, the sacrals are depressed and the caudals, early in their series, 

 become laterally compressed. The posterior, inferior ends of the caudal centra present 

 facets for chevron bones; in one anterior caudal, in particular, they are conspicuous with 

 a pronounced enlargement of the centrum in their vicinity. In most of the dorsal verte- 

 bra3 the neural arches have become detached, in the caudals the base at least is generally 

 intact. The zygapophyses are well developed. The articular faces of the centra in the 

 caudals are slightly concave, those of the dorsals are plane. There is a considerable 

 variation in the size of the vertebraj. 



It is altogether probable that more than one species is represented. 



The following measurements in mm. are taken from a number of centra found with 

 others within a limited area : — 





Cer^'ical. 



Dorsal. 



Sacral. 



Anterior 



caudal. 



Median 

 caudal. 



Late 

 cauJal. 



Later 

 caudal. 



Length of centrum 



13;5 

 13-5 

 13-5 



17-0 

 15 

 17-0 



17-0 

 130 

 15 



18-5 

 12-5 

 14-5 



15-5 

 110 

 100 



130 

 70 

 60 



13-0 



Height of articular face 



Breadlh " " 



5-3 



4-5 



A large dorsal from Mackay creek has the following dimensions : — length of cen- 

 trum, 27'0 mm., height of articular face, 220 mm., breadth of articular face, 23"0 mm. 



Ghampsosattrus is known, also, by comparatively complete skeletons from the Lower 

 Eocene of Rheiras, France, and Erqueliuues, Belgium. 



Belly Eiver series. Red Deer river, 1897, 1898 and 1901. 



Vertebrae were collected at Mackay creek.near "Walsh station on the line of the C. P. 

 R., in 1880, by Professor John Macoun ; on Belly river, N. W. T. (Nos 40 and 41), in 

 1881, by Dr. G-. M. Dawson : and at Ross coulee, near Irvine station, by Mr. T. 0. Weston, 

 in 1884. 



