176 



GEOLOGICAL DISTBIBUTIOlir. 



with the aard-vark), the true Carnivora, Sirenia,* ^roboscidea, and 

 Quadrumana. Per contra, most of the older forms have now com- 

 pletely disappeared, and, in fact, no mammalian order, with the 

 possible exception of the Creodonta (Hysenodon), is indicated which 

 has not its living representatives at the present day. Most of the 



■(O-y-G^O-C-E-N-E) 



EOCENE 



BUNOfHERIA 



CRETACEOUS 



Diagram illustbating RELAiioNSmp of Tertiary Mammalia. 



families are such as still exist, and even many of the genera are 

 identical, so that on the whole the mammalian fauna has a decidedly 

 modern aspect. The Miocene Insectivora comprise, among other 

 forms, representatives of the families of hedgehogs, shrew-mice, 

 and moles ; the Rodentia, porcupines, mice, squirrels, rabbits, beav- 

 ers, &c. ; the Cetacea are represented by true whales and dolphins ; 

 the odd-toed Ungulata by the tapir and a number of allied tapir- 

 oids, and the singular giant forms that have been referred to the 

 not distantly removed family of the Menodontidse (Symborodon, 

 Titanotherium) ; by true rhinoceroses and other forms (Hyracodon, 

 Aceratherium) closely allied to them ; and by Equids — Hipparion, 

 Miohippus (Anchitherium) — which diEEered from the true horses 



* Eotherium Egyptiaoum, from tte Mokattam nummulitic limeBtone, is re- 

 ferred to this group by Professor Owen. 



