402 



potamus, rhinoceros, and tapir, as well as to mastodon, genera of which the 

 four first have no longer any species existing, except in the torrid zone ; 

 and of the last, none in any part." 



Nevertheless, there is nothing to authorize the belief, that the species 

 of the torrid zone have descended from the ancient animals of the North, 

 which have been gradually or suddenly transported towards the equator. 

 They are not the same ; and we may see, by the examination of the 

 most ancient mummies, that no established fact authorizes the belief of 

 changes so great as those which must be assumed for such a transforma- 

 tion, especially in wild animals. 



Nor is there any strict proof that the temperature of the northern 

 climates have changed since this epoch. The fossil species do not differ 

 less from the living, than certain northern animals differ from their co- 

 genera of the south : the isatis of Siberia, for example ( canis lagopus), 

 from the chacal of India and of Africa (canis aureus). They therefore 

 ought to have belonged to much colder climates. 



