» 20 



is one third larger than the posterior. The neural canal is 

 low and siibtriangular, resembling very much that of Canis. 

 The pleuropophysial plates for articulation with the ilia are 

 large and stout. The lamina are heavy and concave on their 

 upper side, supporting a very long, stout spine, which is re- 

 troverted and decidedly tuberous at the end. 



The pedicles are deeply notched behind ; and on the fore 

 part, just inside the metapophyses, there is a deep fossa. 



The chief features of this sacrum are decidedly carnivo- 

 rous ; but to what genus or family it should be referred we 

 are unable to say. 



It has some of the characteristics of Canis, but the length 

 and retroversion of the spine, as well as the size of the centrum, 

 prevent this classification. In the general form of the pleuro- 

 poph)'^sial plates it approximates to the seals ; while in its angle 

 and curvature, it partakes of the character of the Uj-sidcB. 



The chief point of interest in this fossil centres in the fact 

 that it was found only a few feet from the brain cast that is 

 described below. 



Measurements of Sacrum. 



M. 



Length of centrum -031 



Long diameter of anterior articular face -024 



Long diameter of posterior articular face -017 



Width of neural canal -oig 



Height of neural canal -on 



Length of neural spine -036 



Extreme width of sacrum -052 



MEGENCEPHALON. 



Megencephalon prim.^vus. Gen. et spee. nov. 



In close proximity to the pelvis of the Uintatherium Leidi- 

 anum, in one of the upper beds we found an intracranial 

 cast, separate from the bone which had enclosed it, and in 

 such preservation as to warrant a partial determination, at 

 least, of the type to which it belonged. Wishing to obtain as 

 full information as the nature of the cast permitted, we put it 

 in the hands of Dr. Spitzka, of New York, who kindly under- 

 took an examination, and sent us the following as the result : 



