From Henry's Fork Divide.
Hyrachyus intermedius, Sp. nov.
Established on the upper true molar series of the right side.
This species is intermediate in size between H. agrarius and H. modestus. As in the latter species; the basal ridge extends around the entire crown of the tooth, with a small interruption on the antero-external lobe. It is more pronounced, in front and less behind than in H. imperialis. The anterior conical buttress is not nearly so well developed as in H. imperialis; the valleys are wide, and the descending fold from the antero-external lobe is obscure, scarcely marked at all in the first. The transverse crests are strongly arched forwards, and the anterior is very much the longer. The peculiar feature of the species is the position of the postero-externa, lobe, which is pushed to the posterior aspect of the tooth; this is carried so far in the last molar that the two external lobes stand on nearly the same transverse line. The antero-external lobe is much the highest point in the tooth, and its the first molar is remarkably sharp. The enamel is considerably wrinkled, but not nearly so much as in H. modestus.
Measurements.
| M. | |
| Length of first molar | ·012 |
| Breadth of first molar | ·0155 |
| Length of second molar | ·015 |
| Breadth of second molar | ·017 |
| Length of third molar | ·0145 |
| Breadth of third molar | ·017 |
From Cottonwood Creek.
Hyrachyus nanus, Leidy.
Pr. Ac. Nat. Sc., 1872, 20.