112 
CREODONTA. 
duced, and the outer distal border quite different; the truncate outline of 
Stypoloplius being represented by a tuberosity. The anterior face of the 
shaft is convex in Stypoloplms, concave in Ursus arctos; the posterior flat in 
the former, convex in the latter. The entire distal end of the tibia is more 
transversely expanded in Ursus. 
This genus, as now defined, is identical with that called by me, -in 
previous papers on the paleontology of New Mexico, Prototomus. It may 
be found to be proper to use this name; but for the present I use an older 
one, which I proposed for similar flesh-eaters of the Bridger Eocene of 
Wyoming. Unfortunately, I am not able to state the number of the tuber¬ 
cular sectorial molars of those animals, as my specimens only have the last 
two preserved. The structure of the separate molar teeth of both jaws is 
identical in the species from the two regions, and it is even possible that 
Prototomus multicuspis is identical with Stypoloplius aculeatus* Cope, which 
is an older name. 
The three tubercular sectorials in the lower jaw, and the two bicuspid 
molars in the upper, distinguish this genus from the allied Oxycena. 
Stypolophus viverrinus, Cope. 
Plate xxxviii, figs. 1-11. 
Prototomus viverrinus^ Cope, Report Vert. Foss. New Mexico, 1874, p. 13; Id. Ann. 
Report U. S. Geog. Siirvs. W. of 100th M., 1874, p. 125; System. Cat. Vert. 
Eocene New Mexico, U. S. Geog. Survs. W. of 100th M., 1875, p. 9. 
This small Carnivore is represented in our collections by portions of 
the skeleton of a single individual. These embrace a cranium somewhat 
distorted by pressure, and with the nose broken off; vertebrae from all parts 
of the column; parts of the humerus, femur, and tibiae. 
Although abnormally depressed in the specimen, it is evident that the 
frontal region was wide, and the muzzle rather rapidly contracted. The 
foramen infraorhitale exterius is large, and issues above the third premolar. 
The molars are worn, indicating an adult animal. The first jDremolar is 
wanting in the specimen; the second is compressed, and with the median 
cusp rather low; its base is produced anteriorly, but is without tubercle. 
The heel is elongate, trenchant, and recurved behind. The third and fourth 
* Triacodon aculeatus, Cope, Proc. Ainer. Philos. Soc., July, 1872. 
