chap. vn.J MAMMALIA OF THE NEW WORLD. 155 



The peccary (Dicotyles), now a characteristic South. American 

 genus, is a recent immigrant from North America, where it 

 appears to have been developed from ancestral forms of swine 

 dating back to the Miocene period. 



Antelopes are an Old World type, but a few of them appear to 

 have entered North, and reached South America in late Pliocene 

 times. Camels, strange to say, are a special North American type, 

 since they abounded in that continent under various ancient 

 forms in the Miocene period. Towards the end of that period 

 they appear to have entered eastern Asia, and developed into the 

 Siberian Merycotlieriurn and the North Indian Camelus, while 

 in the Pliocene age the ancestral llamas entered South 

 America. 



Cervidce are a wide-spread northern type in their generalized 

 form, but true deer (Cervus) are Palsearctic. They abounded in 

 Europe in Miocene times, but only appear in North and South 

 America in the later Pliocene and Post-Pliocene periods. 



True oxen (Bovince) seem to be an Oriental type (Miocene), 

 while they appear in Europe only late in the Pliocene period, 

 and in America are confined to the Post-Pliocene. 



Elephants (Elepkantidce) are an Old World type, abounding 

 in the Miocene period in Europe and India, and first appearing 

 in America in Post-Pliocene or later Pliocene times. Ancestral 

 forms, doubtfully Proboscidean (Dinocerata), existed in North 

 America in the Eocene period, but these became extinct without 

 leaving any direct descendants, unless the Brontothcridcc and 

 rhinoceroses may be so considered. 



Marsupials are almost certainly a recent introduction into 

 South and North America from Asia. They existed in Europe 

 in Eocene and Miocene times, and presumably over a consider- 

 able part of the Old World ; but no trace of them appears in 

 North or South America before the Post-Pliocene period. 



Edentata. — These offer a most curious and difficult problem. 

 In South America they abound, and were so much more nu- 

 merous and varied in the Post-Pliocene and Pliocene, that we 

 may be sure they lived also in the preceding Miocene period. A 

 few living Edentates are scattered over Africa and Asia, and 



