Douglass — New Species of Meryooclioerus in Montana. 435 



of the posterior border. The posterior border is slightly raised 

 laterally. The condyle is not quite so broad transversely as 

 the glenoid surface with which it articulated and is more 

 narrowly convex antero-posteriorly. The masseteric fossa 

 descends only a short distance — to a line connecting the base 

 of the lobe of m 3 and the posterior angle above mentioned. 

 The bone is injured in the region of the coronoid process so its 

 form cannot be made out. A broad convexity begins at the 

 posterior part of m 3, extends forward and downward to the 

 anterior lower border of the ramus, branches at the mental 

 foramen and continues to the alveolar border &t pm 2, thus 

 leaving a depression under pms 3 and 4- amd ms 1 and 2. 

 The length of the dental series is two-thirds the length of the 

 jaw. 



Merycochcerus laticeps. 

 Skull with jaw, x J. 

 The mandible is too far ahead on account of slight forward displacement of 

 post-glenoid process. 



Dentition. — Superior : The crowns of the incisors and 

 canines are not preserved. The upper incisors were small, 

 quite close together and in a transverse row. The roots of the 

 first and second are laterally compressed. They were nearly 

 the same size, but the third was a little larger. In cross-sec- 

 tion the roots of the canines are three-sided with rounded 

 angles, the posterior side being the broadest: Pm 1 is com- 



