192 EASTERN ARCTOG^A. [CHAP. 



(P.); while the creodont division of the order is represented by 

 Hyanodon, Pterodon, Oxycena (P.), and Proviverra. Among the 

 rodents we may note the squirrel-like Sciuroides (P.S.) and Pseudo- 

 sciurus (S.), the existing genus Sa'urus, and the extinct Plesiarctomys 

 and Plesiospermophilus, which likewise belong to the same family. 

 Among the Muridce, Cricetus includes ancestral types of the 

 hamsters ; while the dormice are represented by the existing genus 

 Myoxus., As noticed previously, Theridomys, Nesocerodon, and 

 Protechinomys seem to be ancestral forms allied to some of the 

 existing South American rodents. 



The ungulates are very strongly represented; the pig-like 

 group including Cebochoerus, Cheer opotamus and Elotherium (P.) 

 among the Chcsropotamida^ Acotherulum, and Anthracotherium (P.) 

 and Ancodus in the Anthracotheriidce. The anoplotheroids com- 

 prise Anoplotherium, D aery t her ium, and Xiphodon ; Dichobunus 

 and Ccenotherium (P.) are the characteristic forms among the 

 Ccenotheriidce; and Dichodon, Gelocus, and Lophiomeryx among the 

 DichodontidcR\ while the chevrotains are represented by Prodremo- 

 therium (P.) and Bachitherium (P.). In the perissodactyle section 

 of the same order, we have Pachynolophus (P.) to represent the 

 Lophiodontidce, Palceotherium and Anchilophus in the Palceo- 

 theriida, Protapirus (P.) as an ancestral form of the tapirs, and 

 Rhinoceros (P.), Cadurcotherium (P.), and Hyrachyus (P.) as 

 representatives of the rhinoceroses. The aberrant Chalicotherium 

 has also one species from the phosphorites. The Effodientia in- 

 clude Leptomanis (P.), Necromanis (P.), and Palceorycteropus (P.); 

 while the existing genus Didelphys alone represents the mar- 

 supials. 



It will be seen that in this fauna the existing generic types are 

 very few, and if the whole of the extinct ones had been given, their 

 relative proportion would have been still less. The ungulates were 

 abundant, and among these the perissodactyles proportionately 

 more numerous than at the present day ; while the anoplotheres 

 are in some respect transitional between the latter and the typi- 

 cal artiodactyles. All the ungulates had brachydont teeth, and 

 annectant types between the modern pigs and ruminants were 

 abundant ; the traguloids being the highest development among 

 the artiodactyle section of the order. Creodont carnivores still 



