DAKOTA AND NEBRASKA. 361 



Another family, the Agrlochceridoi, nearlj allied to the former, is peculiar to the 

 miocene of the Mauvaises Terres. 



The CameUdce are represented in the North American miocene, pliocene, and 

 quaternary deposits, but particularly in the miocene, and they are yet represented in 

 the existing fauna of South America. 



The Moschidce are represented by the genus Leptomeryx in the Dakota miocene, 

 but not in the later formations of North America. 



The Cervidce are represented in the pliocene and succeeding epochs of North 

 America. 



The Antilopidce are represented by a genus in the Niobrara pliocene. 



The Gapridce and Bovidce are not represented in North America prior to the qua- 

 ternary period. 



Of Arthdactyla, exclusive of the Ruminantia, the remains of seven species of six 

 genera belong to the Dakota miocene, of which two genera, Elotherium and Hyopota- 

 mus, are common to the European tertiary. The remaining genera, in part but im- 

 perfectly known, appear to be peculiar. The Niobrara pliocene presents us with 

 traces of a Peccary, but this probably may belong to a later period. 



One of the artiodactyle genera of the Dakota miocene, the huge Tltanotherium, was 

 represented by the nearly allied Ghalicothermm of the European and Himmalayan 

 miocene period. 



Of uneven-toed pachyderms, or Perissodactyla, the Dakota miocene presents an 

 Aceratherium, a peculiar genus of the same family, the Hyracodon, and a species of 

 LopModon. The former and latter are both European tertiary forms. Another 

 member of the Rhinoceros family, R. hesperius as it has been named, from Calilbrnia, 

 was probably an Aceratherium of miocene age. R. meridianiis, of Texas, was proba- 

 bly likewise of the same category as the latter. 



The Niobrara pliocene presents us with three genera — Rhinoceros, Mastodon and 

 Elephant. The foi'mer, apparently a true Rhinoceros, has not been found in the 

 American quaternary formations, though abundant in the European equivalent, 

 and continuing to exist in Asia and Africa. The Mastodon belonged to the subgenus 

 Tetralopliodon, while that of the quaternary period was a Trilophodon. Elephants of 

 other species were nearly cosmopolite during the quaternary period ; but two species 

 now alone live in Asia and Africa. 



Five genera of solipeds appear to have lived in North America during the miocene 

 period. Three of them are peculiar, and appear not to have been discovered else- 

 where. They have been named Anchlppus, from Texas, Eypohip)pus, from the Nio- 

 brara River, and Ancliippodris, from New Jersey. The remaining genus, Anchi- 

 therium, characterized by an abundance of remains from the Mauvaises Terres, belongs 



also to the European miocene. 



46 



