chap. vii. 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 Mmjcothmum 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 Paleearctic. 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 ( Elephantidce ) 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 Brontothe-ridce 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 
