33 



M. 



Depth of mandible at cotylus - 040 



Depth of sphenoid condyle -. 032 



Width of proximal articular surface of quadrate, (transverse) . . . .023 



Width of distal articular surface 043 



Length of third cervical centrum 062 



Depth at bottom of third cervical centrum 030 



Width at bottom of third cervical centrum 037 



Length of articular end of fixed hypapophysis 025 



Length of free hypopophysis 029 



Length of a median dorsal centrum 072 



Width at bottom of a median dorsal centrum 048 



Depth at bottom of a median dorsal centrum 040 



This species needs only to be compared with the Clidastes stenops, Cope, 

 which exhibits the same peculiarity of roof-shaped pre-frontal bones. 

 That species has the cervical articular faces entirely round ; the frontal 

 bone is keeled in the middle, and the palatine much more vertically 

 compressed. The quadrate bone differs in various respects ; among 

 others, in the round form of the stapedial pit. As compared with the 

 species described by Professor Marsh as Edestosaurus dispar and U. velox, 

 it differs in the form of the quadrate, which in these species is much as 

 in G. tortor and C. stenops ; i. e., with short proximal hook, oblique in- 

 ferior articular surface, round pit, &c. In this species the quadrate is 

 truncate distally, &c. 



This fine species w^as discovered by the veteran geologist Prof. B. F. 

 Mudge, during his annual expedition of 1873. 



aa. Frontal bones with median keel : 

 Clidastes tortor, Cope ; Edestosaurus tortor j Cope, Proceed. Amer. 

 Philos. Society, Dec, 1871. 



Mobrara Cretaceous of the Smoky Hill Eiver. 



Clidastes stenops, Cope; Edestosaurus stenops , loo. cit. Hayden's An- 

 nual Keport U. S. Geol. Survey, 1871, p. 330. 



Niobrara Cretaceous of the Smoky Hill Eiver. 



Clidastes rex, Marsh, Amer, Journ. Sci. Arts, 1872, June. 

 Mobrara Cretaceous of the Smoky Hill Eiver. 



Clidastes affinis, Leidy, Esport U. S. Geol. Survey Terrs., I, p. 281, 

 tab. xxxiv, f. 6-9 and 11. 



Niobrara Cretaceous of the Smoky Hill Eiver. 



aaa. Froutal bones unknown : 

 Clidastes dispar, Marsh ; Edestosaurus (Zispar, Marsh, Amer. Journ. 

 Sci. Arts, 1871, June. 



Mobrara Cretaceous of the Smoky Hill Eiver. 



Clidastes velox, Marsh, loe. cit. {Edestosaurus). 

 Niobrara Cretaceous of the Smoky Hill Eiver. 



Clidastes vymanii. Marsh, loc. cit. 



Mobrara Cretaceous of the Smoky Hill Eiver, Western Kansas. 

 3b 



