ANCIENT AMERICA. 335 



to believe that this favourable condition of things con- 

 tinued in a diminished degree during a portion of the 

 succeeding Pliocene period. 



We must not forget, however, that the faunas of the 

 two continents were always to a great extent distinct 

 and contrasted such important Old- World groups as 

 the civets, hyaenas, giraffes, and hippopotami, never 

 passing to America, while the extinct Oreodontidae, 

 Brontotheridae, and many others are equally unknown 

 in the Old World. This renders it probable that the 

 communication even in the north was never of long 

 continuance ; while it wholly negatives the theory of an 

 Atlantis bridging over the Atlantic Ocean in the Tem- 

 perate Zone at any time during the whole Tertiary 

 period. 



But the past history of the North-American fauna is 

 complicated by another set of migrations from South 

 America, which, like those from the Old World, appear 

 to have occurred at distant intervals, and to have con- 

 tinued for limited periods. In the Post-Pliocene epoch, 

 along with elephants and horses from Europe or Asia we, 

 find a host of huge sloths and other Edentata, as well as 

 llamas, capybaras, tapirs, and peccaries, all characteristic 

 of South America. Some of these were identical with 

 living species, while others are closely allied to those 

 found fossil in Brazilian caves and other deposits of 

 about the same age, while nothing like them inhabited 

 the Old World at the same period. We are therefore 

 quite sure that they came from some part of the Neo- 

 tropical region ; but the singular fact is, that in the 

 preceding Pliocene epoch none of them are found in 

 North America. We conclude, therefore, that their 



