The tarsus is arranged in the usual Perissodactyle order. The calcaneum is stout, of good length, tuberous, but not expanding much at the extremity; presenting two faces for the astragalus, of which the internal is the largest, and a large distal face for the cuboid. The astragalus is wide, with less asymmetry in the two articular facets than is common. It articulates with both the cuboid and navicular.
Measurements of Tarsus.
| M. | |
| AAstragalus, total width, tibial facets | ·048 |
| Astragalus, total length | ·056 |
| Astragalus, length, navicular facet | ·046 |
| Astragalus, width, navicular facet | ·035 |
| Calcaneum, total length | ·120 |
| Calcaneum, total breadth | ·057 |
| Calcaneum, length of tuber calcis | ·050 |
All the above were found at Henry's Fork Divide. In another locality, in connection with a fine head of P. major, was found the lower half of a humerus.
The shaft is cylindrical and twisted, expanding widely at the distal end. Of the two condyles the external is the largest; and, to quote from Dr. Leidy, "a deep supra-condylar fossa occupies the front of the humerus, opposed by a deeper and more capacious anconeal fossa." The greatest breadth between the supracondyloid eminences is ·091 m.
Palæosyops paludosus, Leidy.
Cont. to Ext. Vert. Faun, P. lævidens Cope. U. S. Geol. Survey of Terrs, 1872, p. 591.
Specific characters.—Second superior molar has but one outer tubercle. The cones are low as compared with P. major. The cingula are much less developed. The angle of the lower ramus is much longer. The zygoma is massive and wide. An internal process on the glenoid cavity. Temporal fossæ very deep. Crest of occiput nearly in same vertical line as occipital condyles.
The full details of P. paludosus, which follow, may seem somewhat unnecessary, to one familiar with the comprehensive work of Dr. Leidy upon the subject. Care has been taken not to retrace any of his steps; and the descriptions given below are of those parts of the animal which he did not possess at the time of writing. They include (1) a cranium perfect posterior to the orbits; (2) a right ramus mandibuli, with full dentition, except the first premolar; (3) portions of the fore-limbs, scapula, and pelvis, pes and manus, and many fragments of other parts.
Among the first discoveries on Cottonwood Creek, in a stratum of fine green sand, was a head of P. paludosus, complete posteriorly, and broken off just behind the orbit. A rear view of this has been admirably figured in [Plate I].