NIMEAVID^. 993 



Pliocene and Upper Miocene formations increases the probability of the 

 correctness of this supposition. I have ascertained that the American Plio- 

 cene saber-tooths of the genus Smilodon possess the characters of the Felidce 

 rather than those of the Nimravidce. 



Four or five species only of Roplophoneus are known as yet, all from 

 North America. We may expect, however, to find the genus in various 

 parts of the world, wherever the beds occur which represent the time im- 

 mediately preceding the epoch of the true saber-tooths. The longest known 

 species is the HoplopJioneus primceviis Leidy, from the White River bad lands 

 of Dakota and Nebraska. It is about as large as the Canada lynx, and has 

 long and slender superior canines. A larger species, the E. occidentalis 

 Leidy, from the same horizon and locality, is known from two jaw frag- 

 ments as large as the corresponding parts of the Nimravus gomphodus. Al- 

 though the oldest members of the Nimravidce yet known from North Amer- 

 ica, the Brepanodon characters of the mandible and of the superior canine 

 tooth are well developed, much more so than in the false saber-tooth group 

 of the later John Day epoch. In Europe, however, it must be remembered 

 that the latter division commences still earlier; i. e., in the Upper Eocene, 

 in the genus ^lurogale Filhol. 



As I have not obtained any parts of the H. primcevus and H. occidentalis 

 not already described by Leidy, I confine myself at present to a descrip- 

 tion of the H. oreodontis and H. cerebralis. 



HOPLOPHONEUS OREODONTIS CopC. 



Annual Keport F. V. Haydeu, U. S. Geol. Survey Terrs., 1872 (1873), p. 509. Machcerodxis oreodontis, 

 Synopsis of New Vertebrata Colorado, Misc. Pub. U. S. G. S. Terrs., 1873, p. 9. 



Plate LXVII a, fig. 17 ; LXXV o, figs. 1, 2. 



•This saber-tooth was described from the fragment of a mandibular 



ramus supporting the temporary dentition. Subsequently I obtained at the 



same locality a large part of the skull, with portions of some of the limb 



bones of a fully grown specimen. The permanent dentition is in place, and 



is but little worn, while the epiphyses are not yet attached to the long 



bones. This specimen enables me to give a much fuller account of the 



species than heretofore. 

 63 C 



