324 THE PUERCO FAUNA. 



MIOCL^NUS Cope. 



PaleoDtological Bulletin No. 33, p. 489, Sept. 30, 1881; Ibid., No. 34, p. 187, Feb. iO, 1882; Aioer. Nat. 

 18S1, p. 830, Sept. W; Proceed. Amer. Pbilos. Soc., 1881, p. 489; Loc. cii. 1883, p. 547. 



1 ? 3 



Dental formula; I. ?; C. r-, Pm. v ; ^I- k- First and second superior pre- 



14 3 



molars without internal lobe; fourth with one extemal cusp, and a more or 

 less developed internal heel or cingulum; all the inferior premolars without 

 internal cusp. Tiiie molars of superior series, with but one internal tubercle, 

 connected by a low rid<re with two intermediate tubercles and two external 

 tubercles. Inferior molars tubercular, the third with a tifth lobe or heel. 



More or less of the dentition of nine species of this genus is known. 

 The only one of which any part of the skeleton is known is the M. fi.rox. 

 The typical species is the M. turgvlus. 



The bones of the Mioclcenus ferox enable me to refer the genus approxi- 

 mately to its proper position in the systen). Although we do not possess 

 the corresponding parts of the MioclcenKs tun/iilus, the type of the genus, 

 it is probable, if not certain, tliat they agree in generic characters. The 

 agreement in dentition extends to all the principal technical points, though 

 the specific diflFerences are marked. 



The skeleton is that of a creodont. The peculiar involution of ths 

 zygapophyses of the posterior vertebrae, is seen in Mesonyx and in some 

 Artiodactyles. The unequal phlanges are comj^-essed claws, and the meta- 

 podial bones have protuberant condyles. The astragalus has a simple head 

 with convex surface, and the trochlea is a shallow open groove. 



The tubercular dentition refers this genus to the Arctocyonidce* With 

 this famil}'- it is accordingly placed provisionally. It differs from the known 

 fossil genera in the single tubercle of the internal part of the crown of the 

 superior molars. 



The species M. hrachystomus and M. etsagicus of the Wasatch epoch 

 have been removed from this genus. I have shown that the former is an 

 Artiodactyle. Now, in technical points, the dentition of those species is 

 identical with that of Pantolcsten Cope, as well as with Miodceniis. Although 

 the skeleton of the type of Fantolestcs. P. lonykaudus of the Bridger Beds, 

 is yet unknown, it is safe to suppose that it does not differ from that of the 



"For the dentition of this-faniily sceJLeiDuiiii', Auuales, Sci. Nat., 1878, July. 



