DISTRIBUTION OF ANIMALS. l6/ 



tion, that animals are exactly adapted to the locali- 

 ties they inhabit ; and that the reason that different 

 localities have different species is because they have 

 different climate, etc. But this is not found to be 

 true. Of course there is some general relation of ani- 

 mals to climate. Those accustomed to an Arctic cli- 

 mate are never found in the tropics, and those belong- 

 ing to forests are never found in the open plains. 

 It is by no means true, however, that localities 

 differ in their inhabitants simply because of differ- 

 ences in conditions. There are many cases where 

 localities with almost identical physical conditions 

 have utterly different animals and plants. South 

 America has a very varied climate, and many locali- 

 ties could be picked out which would match exactly, 

 in their physical conditions, localities of Africa ; 

 and yet their fauna and flora are very unlike. Nor 

 is this all, for there is abundant proof that the New 

 World is as well adapted for Old-World species as is 

 their native home. For instance, America pos- 

 sessed, when discovered, no member of the horse 

 family, but as soon as this animal was introduced 

 by the Spaniards, it ran wild, and increased with 

 marvellous rapidity, and now exists in enormous 

 numbers; indicating clearly that the absence of 

 the horse from the western continent was not due 

 to adverse physical conditions. An even better 

 illustration is Australia. This strange land has a 

 highly peculiar indigenous fauna, consisting, as far 

 as mammals are concerned, entirely of marsupials 

 and monotremes. But this is not because the land 

 is not fitted for other animals, for every European 



