In general features it strongly resembled the tapir, with stout body, slender tail, and very short neck, compensated by a proboscis of considerable length. In comparing the heads of the ancient and modern representatives of this class of Perissodactyles, the points of contrast are the wide stout zygomas, the deep temporal fossæ, the protruding nasals, and the narrow gaps in the dental series of the older type. There are also strong points of resemblance in the structure of the _Palæosyops_ and _Palæothere_. Some of the cranial homologues have been detailed by Dr. Leidy. The femur of the Palæothere is shorter, the tibia longer; they are both much stouter. The tarsus of the _Palæosyops_ is narrower, while the remainder of the Pes is very similar. The pelvis, and particularly the ilium and acetabulum of _Palæosyops_, is more palæotheroid than tapiroid. The similarity of the fore-shoulder in the two types is also striking. The neck of the _Palæosyops_ was probably shorter. In the descending series of _Palæotheres_ terminating in the diminutive _P. minus_, and characteristic of the upper eocene of France, we have an interesting counterpart in the large family of _Palæosyops_, of equal diversity of size and characteristic of our lower eocene, and it is hoped that future discoveries will render a complete discussion of this interesting coincidence possible. LIMNOHYUS, Leidy. Proceedings Academy Natural Sciences, Phil., 1872, p. 242; _Palæosyops_; Marsh, American Journal Sci. and Arts, 1872, p. 122; Hayden's Survey, 1872, p. 592, Cope. _Generic characters._--Resembles _Palæosyops_ in general features. Distinction founded on the possession of two conic tubercles, of the inner series, on the last superior molar instead of one. Limnohyus laticeps, Marsh. _Palæosyops Laticeps._ Am. Journ. of Sc. v. iv. p. 122. _Specific characters._--"Cranium is broad. The zygomatic arches much expanded. The nasals are narrow and elongated, and more like the corresponding bones in Hyrax than those in the larger pachyderms." Fragments of the upper molar and premolar series. The species is determined by measurements given by Dr. Leidy of the second upper molar. LEUROCEPHALUS, _Gen. Nov._ Established on a specimen having a nearly complete dentition, and portions of the cranium. Dental Formula: (I. 3/3, C. 1/1, Pm. 4/4, M. 3/3,) × 2 = 44.