Wild Life of the World 



INTRODUCTION 



Land animals, and in a more limited degree marine animals also, may be regarded 

 from two entirely different points of view. In the one case they are dealt with 

 according to their mutual relationships and affinities (so far as these can be under- 

 stood) ; in the other, they are considered in connection with their geographical 

 distribution on the surface of the globe. The former method of treatment con- 

 stitutes Systematic Zoology, the second is called Zoological Geography, 

 Distributional Zoology, or, shortly, Distribution, and forms the subject of the 

 present work. 



Nowadays it is a well-known fact that while the assemblages of animals of 

 different countries differ more or less markedly from one another, the amount of 

 differences between these assemblages (or faunas, as they are technically called) 

 in many cases does not accord with the distance between the countries in 

 question. The animals of Japan, for instance, are not very unlike those of 

 northern Europe and the mainland of western Asia, while those of Madagascar 

 differ entirely from those of the adjacent continent of Africa. Again, in many 

 respects, the fauna of North America is much more nearly akin to that of northern 

 Asia and Europe than it is to that of South America, And from the study of 

 geology and the remains of extinct animals it has been ascertained that the differ- 

 ence or resemblance between any two faunas depends, not upon the number of 

 miles separating the two areas they respectively inhabit, but upon the presence or 

 absence of uninterrupted land-communication between them during a long period. 

 A connection existed, for instance, at no very remote date between eastern Asia 

 and North America, which doubtless included Japan. On the other hand, 



