DISTRIBUTION OF MAMMALS IN TIME. 569 



mals of the later geological deposits of any given country differ 

 specifically from those now existing in the same country, they 

 are nevertheless referable to the same orders, and are in every 

 respect more closely allied to the present Mammalian fauna 

 than to that of any other country. A few examples will render 

 this perfectly clear. 



Australia at the present day is an altogether peculiar zoolo- 

 gical province, characterised by the abundance and variety of 

 Marsupials which inhabit it. In the Post-tertiary deposits of 

 Australia, however, we are presented with proofs that Marsu- 

 pials were just as characteristic of Australia during late geolo- 

 gical epochs as they are now. In the Post-pliocene period we 

 know that Australia was occupied by Kangaroos, Kangaroo- 

 rats, Wombats, Phalangers, and Carnivorous Marsupials, in 

 every way representing the living Marsupials in zoological 

 value, but specifically distinct, and generally of gigantic size. 



In the same way, South America at the present day is espe- 

 cially characterised by a Mammalian fauna, containing many 

 peculiar forms, the Edentata being especially conspicuous, and 

 having a larger representation than in any other region. Simi- 

 lar but distinct forms, however, are found to have existed in 

 South America anterior to the creation of any existing species. 

 Thus, the modem Sloths of South America are represented by 

 the colossal Mylodon, Megalonyx, and Megatherium. The little 

 armour-plated Armadillos are represented by the equally colos- 

 sal Glyptodon. The Llamas representing in South America 

 the Camels of the Old World are represented by the curious 

 extinct genus Macrauchenia. The Platyrhine Monkeys have 

 their extinct representatives. Fossil Tapirs take the place of 

 the two existing species ; and the Peccaries are represented by 

 at least five extinct species of Dicotyles. 



Similarly, India is at present the only country in which four- 

 horned Antelopes occur ; and it is in the Sivalik Hills that there 

 have been found the two gigantic four-horned Antelopes, which 

 constitute the genera Sivatherium and Bramatherium, 



In Europe, again, the Mammalian fauna of the later Tertiary 

 periods is much more closely allied to that now characterising 

 the Old World, than to that of the New. We have the Lion, 

 Bear, Wolf, Fox, and other well-known Carnivora. Elephants, 

 Rhinoceroses, and Hippopotami, then as now, are characteristic 

 Old World forms. The Ruminants are equally characteristic 

 of the eastern hemisphere, though not exclusively confined to 

 it, and they have numerous and varied representatives in later 

 Tertiary deposits. The Giraffe is represented by the Hellado- 

 therium, and the Bactrian Camel by the Merycotherium of the 



