It has some of the characteristics of Canis, but the length and retroversion of the spine, as well as the size of the centrum, prevent this classification. In the general form of the pleuropophysial plates it approximates to the seals; while in its angle and curvature, it partakes of the character of the Ursidæ.
The chief point of interest in this fossil centres in the fact that it was found only a few feet from the brain cast that is described below.
Measurements of Sacrum.
| M. | |
| Length of centrum | ·031 |
| Long diameter of anterior articular face | ·024 |
| Long diameter of posterior articular face | ·017 |
| Width of neural canal | ·019 |
| Height of neural canal | ·011 |
| Length of neural spine | ·036 |
| Extreme width of sacrum | ·052 |
MEGENCEPHALON.
Megencephalon primævus. Gen. et spec. nov.
In close proximity to the pelvis of the Uintatherium Leidianum, in one of the upper beds we found an intracranial cast, separate from the bone which had enclosed it, and in such preservation as to warrant a partial determination, at least, of the type to which it belonged. Wishing to obtain as full information as the nature of the cast permitted, we put it in the hands of Dr. Spitzka, of New York, who kindly undertook an examination, and sent us the following as the result:
"Sir: The specimen submitted to me is the intracranial cast of some species of Placental Mammals. The cranium had been subject to the influences of the atmosphere, etc., for a considerable period preceding the formation of the cast, and therefore the cast reflects the sutural dislocations which occurred in consequence. The base of the brain cast it is not advisable to attempt to expose, on account of the treacherous nature of the material. The convolutions corresponding to the internal aspect of the Os temporale have not been clearly demarcated by the bone surface. The two narrow eminences on it are casts of the grooves of the middle meningeal arteries. The convolutions of the occipital surface had been well marked, but somewhat obliterated through denudation, etc. The important region bordering on each side of the median fissure, and corresponding to the fronto-parietal suture, is unfortunately as good as destroyed; and with this destruction the key to the interpretation of the specimen is lost. However, this much can be stated with absolute certainty, that the frontal region is sufficiently well preserved to state that its convolutions do not correspond to those of the brain of the tapir, rhinoceros, hippopotamus, elephant, pig, horse, hyrax, manatus, or any ruminant or cetacean.
"They also differ in important particulars from those of the Canidæ, differ less from those of the Felidæ, still less from the Ursidæ, although corresponding to none of them. The outline of the cerebral cast is found in two living animals—the marine otter and the seal. But in the seal the gyri show the transverse interrupting series of sulci, characteristic of extreme brachycephaly; and it therefore cannot belong to any animal corresponding to the seal.