MIDDLE TERTIARIES. 159 



to assume those distributive features that continue to char- 

 acterise them more or less at the present day. The maples, 

 planes, elms, willows, and other dicotyledonous trees con- 

 tained in the middle tertiaries of Europe, bear the closest 

 resemblance to those that still adorn her forests ; and the 

 elephants, hippopotami, rhinoceroses, bears, lions, and tigers 

 of the Old World find their congeneric predecessors in the 

 tertiary mastodons, mammoths, hippopotami, rhinoceroses, 

 cave -bears, tiger -like niachairodi, and camel -like mery- 

 cotheres of the same hemisphere. In like manner the 

 sloths, ant-eaters, armadilloes, and llamas of South America 

 find their geographical prototypes in the megatheres, my- 

 lodons, glyptodons, and macrauchenes, so abundantly fossil 

 in the upper tertiaries of that continent ; while even in 

 Australasia the kangaroo is preceded by the gigantic dipro- 

 todon, the lace-lizard by the megalanea, and the apteryx 

 and emeu by the palapteryx and dinornis. As the miocene 

 and pliocene epochs advance, the more and more do their 

 fossil forms assimilate to those now peopling the same 

 geographical regions, till the fossil may be said to graduate 

 into the sub-fossil, and the sub-fossil into the species still 

 existing. 



In European tertiaries, for instance, we ascend from the 

 eocene or palaeotheroid age to the elephantoid or middle 

 tertiary, and from this again to the later age of ruminants 

 antelopes, deer, and oxen. Connected as Europe has been 

 with the rest of the Old World ever since the earliest ter- 

 tiary epoch, we might naturally expect to find many species 

 spreading indiscriminately over the other continents of Asia 

 and Africa ; but while this undoubtedly occurs, there are 

 camel-like, giraffe-like, and antelope forms merycotherium, 

 sivatherium, Iramatherium, and the like peculiar to the 

 tertiaries of Asia, W 7 hich point to distinctive geographical 

 distributions of life that obtained so early as the middle and 



