I)(jUGLASS : Verikbrates from Montana Tertiary. 



185 



Each has three longitudinal convexities on the inner face, also many 

 minute wrinkles or discontinuous striations covering these. 



The cheek teeth seem ridiculously small for such a large, robust 

 skull. It seems that the animal was particularly fitted for gnawing, as 

 j]/y/i7x'cJu///s was for grinding or breaking hard substances. The third 

 ])remolars (the first of the back teeth) are both shed, but the alveoli 

 show that thev each had but one small root. 



P"lG. 25. Same as 24. I.owcr view of skull. Natural .size. 



The infraorbital foramina are vertical slits opening at the anterior 

 roots of the zygomatic arches nearer the orbits and higher than in 

 Antomys. Above the molars and inside the zygomatic arch at the 

 lower portion of the orbital fossa is a large convexity. Another is 

 placed above and in front of it. At the posterior portion of the palate 

 is another peculiar structure. There are two cavities between the pos- 

 terior portion of the palate and the opening of the posterior nares. 

 1 am unable to determine in just what proportion the palatines and 

 pterygoids enter into the formation of these cavities. The form is 

 very well shown in the figure. They extend forward a short distance 

 above the posterior portion of the palate. Whether they open ante- 

 riorly into the posterior nares is not quite certain, but if so the open- 

 ing is small. The roof is thin. The posterior border is thick, 

 rounded, and V-shaped. There is a thin jjartition partly separating 



