6 SKETCH or THE HISTORY OF MAMMALIA. 



interesting : among them are found not only the fossil 

 remains of animals allied to existing species, as the fossil 

 elephant or mammoth, fossil rhinoceroses, and others, 

 but also of animals which have now no living represent- 

 atives, and which constitute the types of distinct genera, 

 comprehending exclusively beings whose characters are 

 to be drawn only from their recovered relics, they them- 

 selves having been long blotted out from among the 

 *' things that be," Such are the Mastodon, the Ano- 

 plotherium, the Palseotherium, the Toxodon, the Dino- 

 therium, and many more. 



The order Pachydermata is divided by Cuvier into 

 three sections : the first (Proboscideans) includes the 

 elephants and the extinct Mastodon ; the second (ordi- 

 nary Pachyderms), the hippopotamus, tapir, rhinoceros, 

 and hog, — the Anaplotherium, Palseotherium, and many 

 other extinct forms ; the third (the solidungulous Pa- 

 chyderms) includes the horse and ass. To these we may 

 add a fourth, namely, the aquatic, represented by the 

 Dugong, Lamantin, &<r». 



The sketch of the Pachydermata would properly 

 commence with the Elephant, but to that animal a volume 

 has been devoted, and we therefore begin here with the 

 Hippopotamus. 



The Hippopotamus. 



M. Desmoulins, from an examination of the skulls and 

 skeletons of hippopotami from Senegal and from South 

 Afi'ica, considers that there are two distinct species, 

 which he names respectively H. Senegalensis and H. 

 Capensis. Very probably M. Desmoulins is correct, 

 but as the habits of both species are precisely the same, 

 and as the distinctive characters are founded on osteolo- 

 gical minutiae only, we shall not treat them as diffei'ent, 

 more especially as the point is rather assumed than abso- 

 lutely proved. 



The hippopotamus is a native exclusively of Africa, 

 where, though much more limited than formerly in the 

 range of its habitat, it tenants the banks and beds of the 

 larger rivers, and of the inland lakes from the Gariep to 



