Chapter M

Transverse diameter of proximal articulation ·158
Longitudinal diameter of proximal articulation ·123
Smallest circumference of shaft ·16
Greatest distal circumference above the articular face ·308
Diameter of distal articulation longitudinally ·082
Diameter of distal articulation transversely ·130
Width of tuberosity below pit for ligament of the
patella ·075

Uintatherium princeps, _sp. nov._

Established on several portions of the head, vertebral column, and the limbs.

This species may readily be distinguished from the last by its larger size, the broad nasals with small tuberosities, the stronger zygomatic arches, and the sub-cylindrical centra of the dorsal vertebræ.

The _nasals_ are broad and flat for some distance behind the tuberosities. Although the animal was not adult, the nasal suture is almost obliterated, and is visible only on the inferior surface; in this respect it is very different from the _U. leidianum_, in which the suture persists throughout life; as is shown by the type specimen, which was past maturity. The tuberosities of _U. princeps_ are lower, broader, and more everted than in the preceding species; are not divided by a groove, but united together by a low rounded ridge, to which the surface of the nasals gradually rises from behind. The portion of the bones anterior is short, stout, and projects horizontally.

The _median_, or _maxillary_, _projections_ are apparently short and everted; they are somewhat compressed antero-posteriorly, and enlarge rapidly downwards. They are transversely oval in section.

The _posterior_, or _parietal_, _projections_ are different from any that we have yet seen. They are subtrihedral at base and flattened antero-posteriorly above. The upper margin is regularly arched, and is the thinnest portion of the process. The posterior face is perfectly flat, and the parietal crest makes a sharp angle with it, rising lower down than in _U. leidianum_; the frontal crest is also lower down than in that species, and the anterior face is strongly convex. The internal margin is rounded and straight, and does not show the longitudinal groove marked in the last species.

The _frontal_ has the eminences and depressions common to the members of the genus; but the superciliary ridge is unusually sharp and sinuous in outline.

The _squamosal_ is short, stout, and high; is but slightly curved outwards, but apparently projects somewhat downwards. The malar articulation is broad and flat, indicating the heaviness of that bone. As a whole the zygomatic arch is stronger, and probably shorter, than in _U. leidianum_.

The occipital condyles are proportionately rather small; they are placed on a long neck and project downwards. They are strongly convex from above downwards, but scarcely at all so from side to side. The internal border is slightly emarginate.

The _dorsal vertebræ_ are of about the same proportionate length as in _U. leidianum_, but are higher and wider; and the centra are subcircular in section, slightly contracted in the middle. The costal surfaces are wide and deep, and vertically oval in shape; they are placed partly on the centra and partly on the neurapophyses. The transverse processes are short, stout, and tuberous, and raised high above the centrum. There is a deep notch at the posterior edge of this process, at its junction with the neurapophysis. The neurapophyses are trihedral, somewhat low, and very stout, forming a wide neural canal.

The _ulna_ (Plate VII. Fig. 2) is thick, with a long and rugose olecranon. The shaft is long and stout; it shows a distinct medullary cavity. The distal end is small, and shows a low, heavy, styloid process.

A _metacarpal_ resembles the corresponding bone in _Dinoceras_, but is rounder and less rugose. There are two faces for carpal articulations, which meet at an open angle.

_Measurements._