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. _General appearance._--The base of the cranium is of great width; the occiput is high, inclined very slightly backwards, and deeply concave from side to side. The forehead is triangular and narrow. The temporal fossa is of immense size and depth, leaving a small intracranial cavity. The zygomas are heavy, and arching widely outwards give this part of the head a strong resemblance to the _Felidæ_.