100 



The relative positions of the paramastoid an'd mastoid processes, the audi- 

 tory archway, and the post-glenoid tubercle are nearly the same as in feline 

 animals, but here the resemblance ceases. 



The paramastoid process is a comparatively slight roughened eminence, 

 situated just above and external to the position of the fore part of the con- 

 tiguous condyle. It is separated from the mastoid process by an archway 

 directed inward and forward to the space usually occupied by a tympanic 

 bone, but which in the specimen is filled with the matrix of the fossil. 



The mastoid process, though much broader and longer than the paramastoid, 

 does not project so much downward as the occipital condyle. It is semicir- 

 cular below and roughened, and is compressed from without inwardly. Its 

 outer surface presents a median fossa at the base. 



The auditory archway expands outwardly in a funnel, and ' below is 

 partially contracted by a short ledge, a process of the tympanic, projecting 

 from the mastoid process. 



The root of the zygoma is of great strength, and has, projecting downward 

 from it, a post-glenoid tubercle of extraordinary size. The process is 2£ 

 inches in width, and projects externally in a rounded knob. Its lower part 

 forms a slightly irregular flat surface, just above which, the tubercle is 1£ 

 inches thick. Its inner extremity slopes upward and inward. 



The glenoid articulation is transverse, and its surface straight in this direc- 

 tion. Upon the post glenoid tubercle the surface is vertical until it curves 

 forward and upward to the anterior edge of the zygomatic root. • Its forward 

 extension is about equal to that downward. The glenoid articulation is evi- 

 dently adapted especially to a hinge-like motion, though- not so restricted as 

 that of carnivores. 



Measurements derived from the cranial specimen of Uintatherium are as 

 follows : 



Inches. 



Breadth of the cranium at the outer part of the post-glenoid tubercles 10 



Breadth of the cranium at the mastoid processes 7£ 



Width of the basi-occipital in front of the occipital condyles 2f 



Breadth of the occipital condyles together 6 



Breadth of each condyle 2£ 



Depth of each condyle .' 3 



Distance between the condyles or breadth of the occipital foramen 2£ 



Length of the temporal fossa fore and aft 7 



Breadth of cranium between the temporal fossae where deepest, about 4£ 



Depth of cranium from bottom of supra-cranial basin to basi-occipital, about 4J 



