ORDER UNGULATA. 1 323 



corded from the Middle Miocene of Bavaria may be generically dis- 

 tinct. Allied to this genus are Hemichterus of the Quercy Phos- 

 phorites, and Leptochcerus of the North American Miocene, in which 

 the premolars have a very simple structure. All these forms, to- 

 gether with the following genus, are placed by some writers with the 

 Suidce. The type genus Chceropotamus occurs in the Upper Eocene 

 of France and England, and has been erroneously stated also to 

 occur in the Miocene of Bavaria. The upper true molars resemble 

 those of certain species of Afithracotherium, but have shorter crowns, 

 with a less approach to a selenodont structure. There is a third 

 lobe to the last lower true molar, and the dental formula is 



/. -, C. '-, Pm. -, M. -. The feet are unknown, but it is probable 



3 1 3 3 



that they were furnished with four digits. The type species C. 

 gypsorum of the Paris gypsum, was an animal of the size of a large 

 Pig ; and it is probable that this genus is a survivor of a form which 

 was the common ancestor of both the Suidce and the Anthracothe- 

 riidce. Elotherium, which has been also described under the names 

 of Entelodon, Archaotkerium, Oltinotherium, and Pelonax, is a larger 

 form allied in many dental characters to Chceropotamus ; and is one 

 of the very few members of this suborder in which the last lower 

 true molar has no third lobe. The premolars are relatively large 

 and simple ; the canines recall those of some of the Carnivora; and 

 the functional digits of the feet are reduced to two. The dental 

 formula is the typical one ; and the genus is placed by some writers 

 in the Anthracotheriida. Its remains are found in the Upper 

 Eocene Phosphorites of Quercy, in the Lower Miocene of Ronzon, 

 in France, and of Hempstead in the Isle of Wight, and also in the 

 Miocene of North America. Apparently allied to this genus is 

 Tetraconodon of the Pliocene of the Indian Siwalik Hills, in which 

 the last lower molar has a third lobe, and the conical premolars are 

 of enormous size. In this neighbourhood must probably also be 

 classed the remarkable North' American Eocene genus Achcznodon 

 (probably identical with Parahyus) which has, however, been con- 

 sidered by Professor Cope as allied to the Lemuroidea and Insecti- 

 vora. The structure of the teeth is like that obtaining in the pre- 

 sent family, and the last lower molar has a third lobe, but the first 

 premolar is wanting in both jaws. The skull presents, however, 

 several Carnivorous features, and it is possible that this genus should 

 rather be placed among the bunodont Condylarthra in the neigh- 

 bourhood of Periptychus. The resemblance presented by the teeth 

 of the latter to those of Elotherium and Achcenodon is, indeed, so re- 

 markable as to suggest that those two genera may be descendants 

 of some unknown member of the Condylarthra very closely allied to 

 the Periptychidce. 



