THE SKULL OF PALEORHINUS 145 
upper border is quite elevated and is limited by a broad shallow sinus 
from the remainder of the upper margin of the bone. ‘The lower 
anterior process is much shorter and blunter than is that of Rhytidodon. 
Instead of being drawn out to a point it ends in an enlarged, oblique, 
vertical face of triangular shape. ‘The lower posterior border is 
rounded and presents a large, roughened surface for the attachment of 
muscles. The postacetabular process has been broken off but was 
doubtless similar to that in Rhytidodon. The upper border was 
doubtless somewhat convex, although not so much so as in Riytidodon, 
Fic. 8.—Ilium of Paleorhinus bransoni Williston. 
but as already stated its convexity is. interrupted by a broad sinus, 
giving the anterior part a decidedly concave outline. 
On the inner surface the bone is relatively smooth except for the 
long, shallow trench along its upper part for the reception of the 
sacrum. ‘This trench is outlined along much of its length by slightly 
elevated and angular ridges. Below this trench there is also at the 
anterior extremity of the bone a shallow, ill-defined depression. 
The new features which the present study has disclosed may be 
here summarized. ‘The presence of the otic capsule and its relations 
and dimensions have been determined. ‘The sutural relations of the 
palatine, pterygoid, and vomer have been more clearly delineated, and 
the unsuspected posterior extension of the latter element as far as the 
presphenoidal vacuity demonstrated. It is believed also that the 
