8 THE MAMMALIA. 



stands in sharp contrast with the reduced dentition 

 of most of the ruminants, which lack the upper 

 incisors ; the only point of connection would seem 

 to be the camel, which again has a much fuller 

 dentition. Nevertheless, the horse remains a phe- 

 nomenon so peculiar within itself, that descriptive 

 zoology has always classed the genus Horse which 

 is limited to a few species in the order of the two- 

 hoofed animals, which contains a number of different 

 genera and several hundred species. 



It is much the same with the perfectly unten- 

 able order of the many-hoofed or thick-skinned 

 animals, for it is made to comprise entirely different 

 members. What a peculiar form, for instance, we 

 have in the elephant among the thick-skinned 

 animals, or, indeed, among the whole class of 

 Mammalia : a strict vegetarian, and yet in every 

 respect an oddity among the plant-eaters. The 

 caps of horn, somewhat like nails, which cover 

 the points of his toes, can scarcely be called hoofs. 

 The form of his skull, his teeth and his trunk, in 

 like manner, separate him from all the other plant- 

 eaters in whose society he has figured since the 

 days of Linnaeus. But even among the rest of the 

 so-called many-hoofed animals there is no unity, 

 even according to the interpretation of a later, 



