Specific characteristics.
The premaxillaries (See [Plate X.], Figs. 1-4) are long, with a wide, strongly upward curving process; from the premaxillary symphysis to the third incisor, they increase in thickness; then narrow slightly to the maxillary symphysis. The upper margin of the process is smooth and narrow, curving very gradually upwards; while the lower margin runs more abruptly up, giving to it a strongly pointed curvature.
The outer surfaces are smooth and slightly convex; the inner are marked by a wide deep canal running from just behind the premaxillary symphysis into the maxilla.
The great size of this groove may perhaps be a generic characteristic; as it is much larger than in Protolabis ([Plate X.], Fig. 6), the modern camels, or any of the other ungulates, recent or fossil, that have come under our notice.
The premaxillaries do not co-ossify, as the spines are smooth on their inner side. Just outside the spines, and in front of the deep groove, the bones are marked by numerous small pits for the attachment of the muscles of the upper lip.
The portion of the maxilla in which the first premolar is situated, shows that the maxillaries swell considerably on their alveolar border; for the canine then narrow gradually for the first premolar diastema; then swell for its reception, and become very thin in the diastema between the first and second premolars.
The Teeth.—I. 3/?, C. 1/?, Pm. 1+/?, M. ?/?.
The incisors have quite deep fangs, are cylindrical in shape, vertical in position, and have no basal ridge.
The crown of the first is worn perfectly smooth, flat across the top, unlike the wearing exhibited in any modern form that has come under our notice. The others have their crowns broken, but indicate a nearly subequal series, with the last slightly the largest.
The canines have long, recurved compressed fangs, with rather short crowns, which are circular in section. They are much larger than in Procamelus or Protolabis of Pliocene, or the modern camels. (See [X.], Figs. 3, 5, 6, 7.)