324 PRINCIPLES OF ANIMAL BIOLOGY 



New Zealand, the barriers are such as to affect nearly all animal groups; 

 but they have done so to very unequal degrees. 



One reason for the necessity of different distributional areas for the 

 different kinds of animals is the very different history of evolution of 

 each group. It makes a great difference whether, at the time of geologic 

 isolation of an area, the animals in it are evolving rapidly or are rather 

 stable. Madagascar, for example, is inhabited by mammals belonging 

 mostly to families found nowhere else, but by amphibia, reptiles and 

 insects belonging frequently even to the same genera as those of the 

 African mainland. Australia is peculiar as to its mammals, but much 

 like the Oriental realm (including southeastern Asia and some East 

 Indian islands) in its lizards, butterflies, and earthworms. 



It seems clear now that progress in interpreting the distribution of 

 animals is to be made only by working out the history of each group 

 separately. 



References 



Gadow, Hans. The Wanderings of Animals. G. P. Putnam's Sons. (Chap. Ill, 



the spreading of species; Chap. V, ancient geography inferred from distribution 



and fossils.) 

 Hesse, R., W. C. Allee, and K. P. Schmidt. Ecological Animal Geography. John 



Wiley & Sons, Inc. (Chap. VII.) 

 Rowan, William. The Riddle of Migration. The Williams & Wilkins Company. 



(Chaps. II-IV, bird migration.) 

 ScHARFF, R. F. Distribution and Origin of Life in America. Archibald Constable 



& Co., Ltd. (Chap. XII, fauna and flora of the Galapagos Islands.) 

 ScHARFF, R. F. The History of the European Fauna. Charles Scribner's Sons. 



(Chap. II, general outline.) 



