NIMEAVID^. 949 



flange and latero-anterior angle of the front of the ramus of the lower jaw; 

 (9) in the development of cutting lobes on the posterior borders of the larger 

 premolar teeth. 



(1) The reduction in the luunber of molar teeth. The dental formula 

 of Proceluriis is that of some Viverridce and Canidce, and the reduction from 

 this point to the end of the series is obvious. In Eusmilus, as in Smilodon, 

 the number of molai-s is less by one in the inferior series than in Lijnx and 

 Neofells, where the formula is the smallest known among Felidce proper, 

 viz: f^. (2) The enlarged size of the superior canine teeth. In Procelu- 

 7-HS and Pseudcelurus tlie canines of both jaws are developed as in recent 

 Felidce. In Archcelurus the superior is the larger, but does not, relatively 

 to the molars, exceed that of Felis. It is rather compressed in form and 

 has a sharp cutting edge posteriorly. In Nimravus the superior canine 

 begins to have the enlarged size of the saber-tooths, but its form is peculiar 

 in the N. (jomphodus, being spike-shaped rather than saber-shaped. We 

 find the true saber shape first in the Dinidis, where it is compressed, and 

 with a denticulate cutting edge on both front and rear. In Pogonodon it has 

 reached a very large size, and it does not display much increase in this 

 respect until we reach the last genus of the series, Eusmilus, where its 

 proportions are enormous, almost as large as in the feline genus Smilodon, 

 where they appear to have been an inconvenience to the animal. (3) The 

 diminished size of the inferior canines becomes evident in the lower genera 

 of the third division (supi-a) of the Nimravidce, but is most decided in the 

 highest genera, Hoploplioneus and Eusmilus. (4) The incisor teeth have the 

 usual obspatulate or obovate outline in the genera of the first and second 

 divisions of the family, including Nimravus. They are conic in the true 

 saber-tooths with flared lower jaw, beginning with Dinictis and ending with 

 Eusmilus. (5, 6, and 7) The structure of the sectorials. The presence of 

 a heel and an inner tubercle of the lower sectorial are well-known charac- 

 ters of a majority ot the Carnivora. In only the most highly organized 

 genera are they wanting, and among them are included all those of the 

 Felidce that still exist. In the Nimravidce the inferior genera have both in a 

 reduced degree, and they soon disappear as we ascend the scale. Thus, 

 the inner tubercle is only present in the species of Procehrus, Dinidis, and 



