OREODON OF NEBRASKA. 543 
process, is the anterior condyloid foramen, and anterior to the former, just external 
to the root of the pterygoid processes, is the foramen ovale. 
The glenoid surface is one of the most important features of the skull in reference 
to the habits of the animal. It is broad, and relatively flat, as in existing Rumi- 
nants. Posteriorly, it is bounded by a relatively, very large, post-glenoid tubercle, 
which is transversely compressed conoidal, and more prominent inferiorly than the 
auditory capsule. The anterior two-thirds of the glenoid*surface is slightly convex, 
and directed more forward than in the Deer. Internally, it possesses great extent, 
and is continuous with a large surface of origin for the pterygoid muscles. At the 
base of the post-glenoid tubercle, the surface is slightly concave, and at its external 
part, is directed a little more outwards than in the Deer. 
The pterygoid processes, with the vertical plates of the palate bones, are very 
much more prolonged than in the Deer, and are stronger, especially at the borders 
of the palatine notch. The latter is narrow, and extends as far forward as the 
posterior third of the last molar tooth. The posterior palatine foramina are situated 
in the plates of the superior maxillary bones, anterior to the position of the true 
molars, and usually on a line with the fourth premolar. The two sides of the 
hard palate have more or less disposition to incline towards each other about the 
centre, in some cases being much depressed in this position, but in others not so 
much so. 
The position of the incisive foramina cannot be exactly ascertained, but they 
appear to exist on a transverse line with the canine teeth. 
Orbits —The inner wall of the orbit is but slightly concave compared to that of 
the Deer, and at the inner canthus is bounded by a compressed mamumillary, lach- 
rymal process. Within the latter are two unequal lachrymal foramina. 
Between the floor of the orbit and the lachrymal bone above, is a large, trans- 
versely oval foramen: the entrance of the infra-orbital canal. 
The spheno-orbital foramen, including the homologue of the foramen rotundum, 
is large, and vertically oval, and is situated just within the anterior angular termi- 
nation of the surface of origin for the pterygoid muscles. 
The foramen ovale is placed a short distance in advance of the os petrosa, to the 
outside of the commencement of the pterygoid process, and is almost half the size 
of the preceding foramen. 
Relations of the Bones of the Skull—The occipital bone posteriorly is trilateral, 
with a broad, prominent apex, as in the Camel. 
The lambdoidal suture ascends from the base of the para-mastoid process back- 
wards between the occipital and posterior process of the pars petrosa, to the summit 
of the latter, when it advances on the side to the top of the skull, between the pars 
squamosa, parietal, and occipital bones. 
The parietal bones form but a single piece, and are remarkable, as in the Camel, 
on account of their relatively very great length, when compared to those of other 
recent Ruminants.. They are narrowest posteriorly, and are prolonged on each side 
downwards in advance of the pars squamosa, to join the wing of the post-sphenoid. 
Anteriorly, they are deeply notched for the reception of the posterior extremities 
of the frontals. 
