Distribution 25 



are divided, in descending order, into the Plistocene, Pliocene, Miocene, 

 Oligocene, and Eocene epochs. 



Whether they originated in the Old World or in North America, 

 the American deer passed into South America in the early portion 

 of the Pliocene epoch, when a land connection was first established via 

 the Isthmus of Panama between the northern and southern halves of the 

 New World, and a large number of animals belonging to an essentially 

 northern type poured into South America, where they became mingled 

 with the proper indigenous fauna of that region. In the earlier 

 Tertiary formations of South America, which contain numerous fossilised 

 remains of armadilloes, of the allied gigantic extinct glyptodonts, of 

 ground-sloths, of American monkeys, and of various peculiar groups of 

 Ungulates, those of deer are entirely wanting ; whereas when we came to 

 the Pliocene epoch the latter are abundant. 



To revert to the Old World, great difficulty exists in giving any 

 thoroughly satisfactory explanation of the entire absence of deer from 

 Africa south of the Sahara, more especially as remains of species of an Oriental 

 type occur in the later Tertiary deposits of India. Typical deer of the red 

 deer group are, however, wanting in the Indian deposits, as they are in India 

 at the present day, and as India seems to have been the great distributional 

 feeder of Ethiopian Africa by way of Syria, it is easy to see why there are 

 no members of that group south of the Sahara. With regard to the absence 

 of Oriental types of deer in Ethiopian Africa, it is as difficult to discover any 

 valid reason why these should have continued to flourish in the Oriental 

 region since the Pliocene epoch without having entered Africa, as it is to 

 explain why giraffes, hippopotami, and ostriches, which formerly inhabited 

 the former area, should have completely disappeared from it to find a per- 

 manent home in the latter. The North African red deer of course effected 

 an entrance into the north-western corner of Africa by means of a land- 

 bridge connecting that area with Spain, as did likewise the fallow deer ; the 

 Sahara presenting an impassable barrier to their progress southwards. 



Temperature seems doubtless to have been a factor of some considerable 

 importance in the distribution of the various groups of the family. The 

 members of the red deer group, for instance, have a general distributional 

 area situated approximately between the fortieth and sixtieth parallels of 

 north latitude, although passing somewhat to the north of this zone in 



E 



