NIMRAVID^. 963 



tosis at the base of the inferior sectorial ah-eady mentioned. This growth 

 is symmetrical on the two sides of the skull, and is evidently normal; traces 

 of it are seen in the species of Nimravus. 



History. — The first description of this species was given by myself 

 under the head of the Nimravus hrachyops {Machcerodus brachyops. Pale- 

 ontol. Bulletin 30, p. 10, Dec, 1878), from a skull found by Mr. Sternberg, 

 under the impression that it might belong to a female of that species. Sub- 

 sequently a nearly perfect cranium, obtained by Mr. Wortman, demonstrated 

 the distinctness of the animal, both as to species and genus. I published a 

 wood-cut of this skull in the American Naturalist for December, 1 880. 



Horizon and locality. — The remains of the Archcelurus dehilis have so far 

 been only found in the Middle Miocene formation of the John Day River, 

 Central Oregon. Judging from the remains, it was, after the Nimravm 

 gomphodus, the most abundant feline of that region. 



NIMRAVUS Cope. 



Proceedings of the Philadelpliia Academy, 1879, p. 1G9. 



3 1 3 1 



Dental formula: I. -; C. -; Pm. -; M. -. Superior canines elon- 



gate, denticulate. Mandibular rami not flared downwards in front. Incisors 

 with short subspatulate crowns. Superior sectorial without basal anterior 

 lobe ; inferior sectorial with well developed heel, and no internal tubercle. 

 No intermediate posterior lobes of the premolars. Postglenoid and post- 

 parietal foramina present. 



This genus has the dental formula and characters of Hoploplioneus, 

 with the addition of a tubercular inferior molar tooth. It is, moreover, not 

 a true saber-tooth, as is that genus, since it does not display the inferior 

 anterior flange of the mandible. This is represented by an obtuse angular 

 border, quite as in the species of Archcelurus, in which genus Nimravus finds 

 its nearest ally. The constant absence of the anterior premolars in both 

 jaws distinguishes it sufficiently from that genus. On this account, and in 

 view of the larger development and denticulated edge of the superior canine 

 teeth, Nimravus may be considered as occupying a position between the 

 two genera above named. 



Two species are known to me, a larger and a smaller, both from the 

 Middle Miocene formation. 



