OREODON OF NEBRASKA. 54] 
souri, crania and fragments of crania, and jaws with teeth, more or less perfect, 
of at least twenty-six different individuals of at least two distinct species of Oreodon. 
From this abundant material we are enabled to trace out almost all the anatomical 
details of the head of the animal, which I shall do without the unnecessary reference 
to particular specimens in the course of the description. 
The head in its general form (Tab. x., 4-6; xi., 2, 3), resembles more that of 
the Camel than of any other existing Ruminants. It has an almost unbroken arch 
of teeth in both jaws, composed of molars, canines, and incisors. The head of one of 
the species of Oreodon is about the size of that of the Wolf of Pennsylvania; the other 
is about the size of that of the Badger. To the former I have given the name of 
Oreodon Culbertsonii, to the latter that of Oreodon gracile. The characters common 
to both the species mentioned, I shall now proceed to give in detail as belonging to 
the genus, and afterwards point out the specific differences in addition to the size. 
Side view of the skull—(Tab. x., fig. 5; xi., fig. 2.) The temporal fossa is con- 
structed like that of the Camel, and is relatively about as large as in that animal. 
It rises to the middle line of the cranium, upon a parietal crest extending the whole 
length of the single parietal bone. Posteriorly, it is bounded by an oblique ridge, 
separating it from the occipital surface. Antero-superiorly, it is bounded by a 
slight ridge running outwards upon the post-orbital process. The surface generally 
is convex, is most prominent along the course of the squamous suture, and nearly 
one-half of its extent is constituted by the squamous portion of the temporal bone, 
as in the Camel and Lama. 
In some.of the specimens, the parietal bone along the course of the squamous 
suture and contiguous to it is depressed into a groove. 
The zygomatic arch is relatively much broader and stronger than in any existing 
Ruminants. 
The malar bone is robust, and its outer surface presents upwards and forwards, 
or is on the same plane with the orifice of the orbit. 
The post-orbital process is united, as in existing Ruminants, with the malar bone, 
so as to form a narrow arch. 
The orbital entrance is subrotund, and is directed forward to about the same 
extent as in the Deer, but in a trifling degree more upward. 
The face at its lower part, in comparison with that of the Deer, appears not only 
shortened to an extent equal to the vast unoccupied space anterior to the molars in 
the latter animal, but appears also to recede so as to bring the last molar on a 
line perpendicular to the post-orbital arch. 
The face, from the latter on each side forwards, forms an almost equilateral triangle. 
Its sides are more vertical than in the Deer, and form a continuous convexity from 
the middle nasal suture downwards. 
The most remarkable feature in the lateral view of the face is the very large 
lachrymal depression, which is nearly hemispherical, and extends slightly beyond 
the borders of the lachrymal bone. 
The infra-orbital foramen is situated above the third premolar tooth. 
_ The anterior extremity of the floor of the nose constituted by the superior incisive 
