Cope.] 462 [-Oct. 20, 



CHORISTODERA. 



ChampsosoMrus australis Cope, American Naturalist, 1881, p. 690. 

 Ghampsosaurus puercensis Cope, Proceedings American Philosophical 

 Society, 1881, p. 195. 



Ohampsotaurus saponensis Cope, Loc. cit. 1881, p. 196. 



MAMMALIA. 



MARSUPIALIA. 



Ptilodus media&ous Cope, American Naturalist, 1881, p. 923. 

 Ptilodus trovessartianus Cope, loc. cit. 1882, p. 686. 

 Gatopsalis foliatus Cope, loc. cit. 1883, p. 416. 

 Catopsalis pollux Cope, loc. cit. 1882, p. 685. 

 Polymastodon taoensis Cope, loc. cit. 1882, p. 684. 



BUNOTHERIA. 



Taeniodonta. 



Hemiganus vuUuosus Cope, loc. cit. 1882, p. 831. 

 I'cmiolabis scalper Cope, loc. cit. 1882, p. 604. 



TiLLODONTA. 



Psittacotherium multifragum Cope, 1. c, 1882 p. 156. 

 Psittacotherium aspasice Cope, Proceed. Amer. Philosophical Society, 

 1882, p. 192, (1882). 



Mesodonta. 



Pelycodus pelvidens Cope, Proceeds. Amer. Philos. Soc. 1881, (1882) p. 

 151. Lipodectes peloidens Cope, American Naturalist. 1881, p. 1019. 



Hyopsodus acolytus Cope, sp. -nov. 



This the least species of the genus, is also the oldest, being derived from 

 the Puerco horizon. Parts of two individuals furnish the characters ot 

 the inferior and superior true molars, and the fourth superior premolars. 

 The species differs from those hitherto described in other characters than 

 the minute size. One of these is the absence of posterior interior cusp, the 

 heels of the first and second true inferior molars being bounded by a ridge 

 only at this point, as in most of the species of Pelycodus. The last inferior 

 molar is not smaller tlian the second, nor longer. The anterior cusps of 

 all the molars are robust, so that on the first and second true molars they 

 are separated by a shallow notch only. There is a rudiment of the anterior 

 inner cusp on the tirst true molar but none on the second and third. The 

 posterior external is obtuse and has a triangular section on all the molars ; 

 a crest is continued from the heel of the third molar on the inner side of 

 the crown half way to the anterior inner cusp. 



