g$ irf^ 



503 



Jan. 18, 1884.] o\Jt> rCope. 



Synopsis of the Species of Oreodontidce. By E. D. Cope. 



{Bead before the American Philosophical Society, Jamtary 18, 188 4.. ) 



The tribe Ruminantia first appears in the White River Miocene period 

 in North A.merican geological history. It is represented there by a num- 

 ber of genera, which pertain to several family types. The most aberrant 

 ot these, the Oreodontidm, includes the largest number of forms, generic and 

 specific. The Poebrotheriidm certainly embraces but few species, while 

 a third group of genera, represented by Leptomeryx, which are inter- 

 mediate between the Tragulina and Pecora, and should be perhaps regard- 

 ed as aberrant Tragulidm, also includes a small number of species. 



The Oreodontidce constitute a family related to the Anoplotheriidm of 

 the later Eocene, but representing a more specialized condition of the 

 structure of the molar teeth, in the full development of the selenodont 

 type; which is rudimental in the Anoplotheriidce. Their feet, on the other 

 hand, are less specialized than in the latter family. As a family, the Oreo- 

 dontidm display very little tendency in their limbs to the specialized con- 

 dition of the Buminantia, but are more like those of the suilline groups, 

 and, among recent families, of the Hippopotamidm. 



OREODOATID.E, 



Dentition ; superior incisors present ; molars selenodont. Cervicals 

 with the transverse processes perforated by the vertebrarterial canal . No 

 alisphenoid canal. Ulna and radius, and tibia and fibula distinct. Meta- 

 podial bones four on each foot, with incomplete distal trochlear keels. 

 Lunar bone not supported by magnum. Navicular and cuboid bones dis- 

 tinct. 



The preceding synopsis of its characters should furnish a basis for the 

 definite location of the Oreodontidce in the system. Dr. Leidy called its 

 species Ruminating hogs, and created a family for Oreodon and the allied 

 genera, under the name of Oreodontidm. This family is adopted by Prof. 

 Gill who includes in it the Agriochoeridm of Leidy, and places it in his 

 division Pecora, which is more comprehensive than the Pecora of Prof. 

 Flower, being nearly identical with the Selenodonta of Kowalevsky. 

 More precise expression of its affinity to the existing families is not given, 

 excepting to place it under a division "incertee sedis." 



As a selenodont type, this family is excluded from the Artiodactyla 

 omnivora, and as having its metapodial bones distinct, it cannot be placed 

 in any recent family excepting the Tragulidce. From this family it is 

 distinguished by the distinct ulna and radius. We then turn to the ex- 

 tinct families Poebrotheriidce and Anoplotheriidce. The former agrees 

 with the Tragulidce excepting in its Caineloid cervical vertebrae, 

 while the latter differs from the Oreodontidm in the structure of 

 the feet. The Anoplotheriidce are didactyle in front, and tridactyle 

 behind. The posterior foot has a well-developed second digit directed 



PROC. AMEE. PHILOS. SOC. XXI. 116 3l. PRINTED JUNE 6, 1884. 



