414 
the globe, therefore, nourished formerly species belonging to the 
genus elephant, hippopotamus , 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 transformation, 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. 
