288 THE WASATCH AND BRIDGER FAHN^. 



of Ursus, and the compressed and moderately elevated distal end is that of 

 the former two, rather than like the same region in the latter genus. The 

 distal end of the tibia is unlike that of either of the three genera named, but 

 resembles most that of Ursus. The entirely distinct character of the astra- 

 galar articular extremity has been already described. The anterior end 

 of the shaft is convex in S. viverrinus, flat in Felis and Canis; flat behind 

 in the former, convex in the latter. The external end of the shaft is trans- 

 verse in S. viverrinus, oblique in Canls and Fells; especially so in the former, 

 being more or less parallel with the inner astragalar groove, while in S. 

 viverrinus it diverges from the angle which represents the groove. The ten- 

 dinous groove is wider and better defined than in G. familiaris, more resem- 

 bling that in Felis. The inner malleolus is more anterior in position than in 

 the two genera named, and beai-s a distal articular facet, which is wanting 

 in Felis and Canis. As compared with Ursus arctos, the inner malleolus 

 is more produced, and the outer distal border quite different, the truncate 

 outline of Stypolophus being represented by a tuberosity. The anterior 

 face of the shaft is convex in Stypolophus, concave in Ursus arctos; the pos- 

 terior 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 pre- 

 vious papers on the paleontology of New Mexico, Prototomus. It may be 

 frjund to be proper to use this name, but for the present I use an older one, 

 which 1 proj)osed for similar Carnivores of the Bridger Eocene of Wyoming. 

 Unfortunately, I am not able to state the number of the tubercular-sectorial 

 molars of the S. pungens Cope, the type of the genus, as my specimens 

 have only the last two in place. The structure of the separate molar teeth 

 of both jaws is identical in the species from the two regions, and the generic 

 characters of the dentition, so far as known, ai'e the same in the best pre- 

 served species, S. multicuspis and S. viverrinus of the Wasatch, and S. acule- 

 atus of the Bridger epochs. The three tubercular-sectorials in the lower 

 jaw, and the two bicuspid molars in the upper, distinguish this genus from 

 the allied Oxycena. 



M. Filhol has described very fully beautiful specimens of species of 

 iS'jypolophus from the Phosphorites of southern central France. He names 





