896 The American Naturalist. [October, 
GEOLOGY AND PALEONTOLOGY. 
A New Plistocene Sabre-Tooth.—During the past summer I 
obtained for the museum of the Academy of Natural Sciences of Phil- 
adelphia, some fossil remains of vertebrata from the western part of 
Oklahoma. These consist chiefly of parts of a single skeleton with 
teeth of Elephas primigenius columbii. Mixed with these were found 
the bones of a sabre-tooth cat. A few of these only, together with 
some teeth, were saved. These include parts of three metacarpals, 
three phalanges of probably a single digit, and the head of the femur. 
The teeth include five incisors, two superior canines, and two molars, 
one of them the superior sectorial in perfect preservation. The animal 
had attained full size, but the epiphysis of the head of the femur is not 
coossified. The dimensions are equal to those of a lion, ( Uncia leo), of 
the same age; and those of the superior sectorial are similar to those 
of the Smilodon fatalis Leidy, and a little smaller than those of the 
S. neogeus Lund, of South America. 
Generic character. So far as preserved, the parts agree with those of 
the genus Smilodon, with one exception. This is that the superior 
sectorial tooth possesses no internal root, not even a rudiment. The 
protocone is wanting in Smilodon, but its corresponding root is present, 
but in this form the root also has disappeared, so that it may be 
regarded as presenting the last stage of specialization in the cats, a cir- 
cumstance which is appropriate to its late appearance intime. I there- 
fore suppose the species to represent a genus, to which I give the name 
of Dinobastis. 
Specific characters. The canine teeth are large, with elongate com- 
_ pressed crowns, a little more convex on the external than the internal 
face. The cutting edges are finely serrate. The anterior edge differs 
from that of the Smilodon neogeus in that it turns inward toward the 
base of the crown, presenting inward. In the S. neogeus this edge is 
not incurved. he superior sectorial has a large anterior basal lobe 
and a rudiment of a second at its anterior base. It does not attain the 
importance of a lobe, as it does in the S. fatalis. The part of the 
crown anterior to the paracone forms about one-fourth of the longitudi- 
nal extent of the crown; in the S. fatalis,is forms about one-third. 
The paracone is prominent, and is strongly convex on the external 
face. The metacone has a nearly straight edge, and its external face 
displays a shallow vertical groove near the middle. "The long diameter 
of its base is 1-5 as great as that of the paracone. The crowns of the 
