1892.] NATURAL SCIENCES OF PHILADELPHIA. 323 



in ml and the greater prominence of the ridge connecting this ele- 

 ment with the protoconid ; the hypoconid is somewhat crescentic 

 and the entoconid reduced, the valley opening inward in advance 

 of that cusp ; the hypoconulid is much enlarged and carried on a 

 distinct fang. It would require but relatively little alteration to 

 convert this tooth into one of true selenodont pattern. 



One species : P. ( Chriacus) rutimeyeranus Cope. Puerco. 



CARCINODON gen. nov. 

 Syn. Mioclcenus Cope, in part. 



This genus is almost certainly unguiculate, bnt whether creodont 

 or insectivorous is not clear, the character of the lower molar teeth 

 somewhat resembling those of the Wasatch Diacodon. P^ and * 

 have high and pointed protoconids and minute posterior basal cusps. 

 The inferior molars increase in size posteriorly and when viewed 

 from the side, the trigonid is seen to curve forward and the talon 

 backward, which gives the crown a claw-like shape. The proto- and 

 metaconids are joined for most of their height and of equal size, 

 and the small but elevated paraconid is placed close to the latter, 

 but connected with the former by a crest ; the talon is a deep basin, 

 with elevated margin, upon which the hypo- and entoconids and 

 the hypoconulids appear as small tubercles. In m^ these elements, 

 especially the latter, are enlarged. 



One species : C. {Mioclcenus) filJwlianus Cope. Puerco. 



The species, Mioclcenus (Beltathernmi) interruptus Cope, 3L min- 

 imus Cope and 31. (Hyopsodus) acolylus Cope should, for reasons 

 already stated, be removed from that genus, but are too imperfectly 

 known for proper reference. The latter {M. acohjtus) may possibly 

 be a forerunner of the Wasatch artiodactyl, Pantolestes. 



Another group of problematical genera is that constituted by 

 Onychodectes^ Cope, Conoryctes' Cope and Hemiganus^ Cope, which 

 are distinguished, among other things, by the remarkable thinness of 

 the enamel which covers the molars. It is probable that these forms 

 should be removed from the creodonts and as Cope has suggested, 

 brought into relation with the tillodonts. 



1 Trans. Am. Phil. Soc, Vol. XVI, Pt. II, p. 317. 



2 Proc. Am. Phil. Soc, 1881, p. 486. 



3 Amer. Naturalist, 1882, p. 831. 



