Douglass — New Species of Merycochcerus in Montana. 437 



M. 



Width of top of skull above orbits "118 



External nares, greatest width -044 



External nares, greatest length "112 



Length of three upper incisors *015 



Length of dental series from front of canine "153 



Length of molar-premolar series "136 



Length of premolar series '056 



Length of molar series '080 



Width of last molar -030 



Lower Jaw. 



Length of jaw, greatest 



Depth at chin ... 



Depth under ml _ 



Depth under back part of m 2 



Depth under last lobe ofm3 



Length of inferior dental series 



Length of molar-premolar series 



Length of premolar series 



Length of molar series 



Space occupied by i 2 and 3 



Width of canine at alveolus, transverse. 



Length of canine antero-posterior 



Width of pm 1 



Length of pm 1 antero-posterior .. 



Length of pm 2 



Width of pm 2 



Length of pm 3 



Width of pm 3 



Length of pm 4 



Width of pm 4 



Length of m3 ._ 



Width of m 3 



Length of foramen mentale 



Width of foramen mentale 



M. 

 235 

 057 

 053 

 063 

 109 

 157 

 150 

 058 

 092 

 008 

 009 

 0065 

 011 

 014 

 014 

 006 

 017 

 0095 

 0185 

 012 

 044 

 0165 

 008 

 005 



From the parts of Merycochcerus proprius that have been 

 described M. laticeps differs in the lateral aspect of the maxil- 

 laries ; the smaller size and, apparently, the more transverse 

 position of the incisors and incisive border ; the absence of a 

 space between pms 1 and #/ the more hypsodont character of 

 the teeth ; the more posterior position of the infra- orbital fora- 

 men ; the smaller size and different shape of the small posterior 

 lobe on the last upper molar ; and the different shape of the 

 mandible, especially its greater posterior depth. 



M. rusticus approaches more nearly to the present species 

 in the facial concavities, in the size and position of the incisors, 



