38 



University of California Publications. [Geology 



NIMRAVUS AND ARCHAELURUS. 

 PI. 4; PL 5, Figs. 1 and 2; and Text-figure 16. 



Generic and Specific Distinctions. The genera Archaelurus 29 

 and Nimravus 30 were established by Cope to include three feline 

 species related to the sabre-tooth forms but having very primitive 

 characters. They were referred to by Cope as the "false sabre- 

 tooths," owing to their lack of a prominent flange on the antero- 

 inferior angle of the lower jaw, and the absence of a cutting edge 

 on the anterior side of the relatively short upper canines. There 

 Avas also noticed in both genera a peculiar exostosis or a thicken- 

 ing of the outer side of the alveolar border immediately below the 

 inferior molars. Neither genus was known outside the limits of 

 the John Day series. Of the two, Archaelurus was said to be 

 the more primitive, having one more premolar in each jaw, and 

 smooth-edged instead of posteriorly serrated upper and lower 

 canines. Other differences between the single species of Archae- 

 lurus and the two placed in Nimravus were supposedly of no 

 more than specific value. 



Though Archaelurus and Nimravus appeared to Cope to be 

 quite distinctly separated, studies of recently discovered material 

 show that they are scarcely separable if not identical generic 

 types. In the University of California collections there are sev- 

 eral specimens which show the skull and dentition of forms be- 

 longing in this group more perfectly in some particulars than 

 they were exhibited in the types. 31 All of this material indicates 

 that Archaelurus is not so distinctly separated from Nimravus 

 as it was considered to be by Cope. 



In a particularly well-preserved skull (No. 1681), pi. 4, and 

 text-figure 15, there is a mixture of the characters of Archae- 



:a Archaelurus. Am. Nat., Vol. 13, Dee. 4, 1879, p. 798a-798&. 



30 Nimravus. Proc. Acad. Nat. Sc., Philad., Aug. 12, 1879, pp. 169 and 

 174. 



31 This material includes the following specimens : No. 1681, perfect 

 cranium without mandible, with axis and one other cervical vertebra; No. 

 1685, cranium with dentition, lacking I 1 and the frontal region; No. 1679, 

 mandible with dentition ; No. 1680, middle portion of mandible with P 3 and 

 Mi, also five lumbar vertebrae; No. 1683, half of mandible with M 2 and parts 

 of other teeth; No. 2256, nearly complete hind limb; No. 110, perfect tibia, 

 calcaneum, fragments of metapodials, caudal vertebrae. In addition to these 

 there are a number of loose teeth and scattered limb bones. 



