CHAPTER XXI 



HOW ANIMALS ARE DISTRIBUTED OVER 

 THE WORLD 



Animals limited to particular regions. — We are used 

 to seeing certain kinds of animals, such as rabbits, robins, 

 field-mice, and garter-snakes in the particular region in 

 which we live, and never seeing others, such as lions, 

 elephants, birds-of-paradise, and boa-constrictors. We 

 know, indeed, that these latter kinds do not live in our 

 region nor even on our continent. But we are too likely 

 to take such things for granted, and not inquire why it is 

 that only certain particular kinds live in North America 

 and certain others in Africa, while others still may be 

 found all over the world. 



As a matter of fact there are few things about animals 

 more interesting to observe than their distribution over 

 the world. Unfortunately in this matter we must depend 

 for many of our facts upon the statements of other people ; 

 we can observe at first hand only a few of them. We 

 can see for ourselves what kinds of animals live in our 

 neighborhood, and that certain other kinds with which 

 we are somewhat familiar from menageries or books do 

 not. We can see that some animals, fishes for example, 

 live always in water ; and that some water animals live 

 always in ponds, while others prefer the brooks. Many 

 other water animals, on the contrary, can live only in 

 the ocean (see Chapter X, on ocean animals), and of 

 these some always keep near the bottom, where it is dark 



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