36 Bulleim American Museum of Natural History. [Vol. XIV, 



view of the fact that in Triisodon, the only other Mesonychid 

 in which the replacement of the teeth has been observed, there 

 is a permanent fourth lower premolar, though protruded rather 

 late in life, considerably after nig (Cope, '84, 270). 



Comparative Measurements 



Cope, E. D. 

 '72. ] 



REFERENCES CITED. 



1. Descriptions of some New Vertebrata from the Bridger Group of 

 the Eocene. Proc. Amer. Philos. Soc. Philadelphia, Vol. XII, 

 p. 460— Palseontological Bulletin No. i, published July 29. 



2. Second Account of New Vertebrata from the Bridger Eocene. 

 ^«'''-. p. 466 = Pal. Bull. No. 2, published Aug. 3. 



' From type specimen, 'e.' = estimated from an incomplete specimen. 



