352 UNGULATA. 



as that of Anoplotherium, is stated to have tridactyle feet, 

 and would thus seem to belong to the Perissodactyle section 

 of the Ungulates. 



Of the other Anoplotheroid genera, we need only mention 

 Dichodon and Dichohime, both of which have marked rela- 

 tions with the XipliodontidcB, and through these with the 

 Euminant group of the Chevrotains {Tragididce). The genus 

 Dichobune, in particular, is nearly allied to Xipliodon, the 

 prpemolars being elongated from before backwards, and, ex- 

 cept the last, sub-trenchant. There is, however, a slight gap 

 between the canines and prsemolars. The genus is from the 

 Eocene of Europe. In the genus Dichodon, also from the 

 Eocene, the dentition is likewise complete, and the molars 

 (fig. 643, D and e) have four-lobed crowns, the cusps of 

 which are sharp and conical, while the canines are small, and 

 differ little in size and form from the incisors. 



Fam. 4. Orcodontidm. — The last of these transitional groups 

 of Artiodactyles which requires notice is that of the Orco- 

 dontidce, comprising a number of curious Ungulates from 

 the Miocene and Pliocene Tertiary of North America, which 

 stand midway between the Snida and the Ruminantia, 

 and have therefore been appropriately termed " ruminating 

 hogs " by Leidy, though we have no actual evidence to show 

 that they really " ruminated." . In Orcodon, the type of the 

 group, we have an even-toed Ungulate, in size about equal 

 to the Sheep, and with characters allying it to the Snida on 

 the one hand, and the Deer on the other. Tlie feet were 

 tetradactylous, and the metacarpals and metatarsals were not 

 anchylosed. The dentition is complete, the dental formula 

 being — 



. 3—3 1—1 4—4 3—3 , , 



% ; e ; j^m ; iii 44. 



3—3 1—1 4—4 3—3 



The incisors are of small size ; and the canines are large, 

 trihedral and worn like those of the Pig, and separated by a 

 diastema from the pra?molars. The privmolars and molars, 

 on the other hand, are of the Ruminant type, the former 

 exhibiting one crescent, and the latter having the regular 

 doubly-crescentic form of the typical Selenodont Artiodac- 



