THE GEOGRAPHICAL DISTRIBUTION 



OF ANIMALS 



By William Berryman Scott 



Blah- Projessor of Geology and Paleontology, Princeton University 



Possible Explanations of Geographic Distribution 



Diiferent kinds of animals are found in different lands or 

 in different seas. Even the animals of the same continent 

 may show great differences, such as those between the 

 animals of the Canadian forests and those of the coast of 

 the Gulf of Mexico. A hasty examination of the facts might 

 lead to the conclusion that animals were spread over the 

 earth altogether in adaptation to climatic conditions, but 

 this would be a mistake, for climate is only one factor in a 

 very complicated problem, and similarity of climate in widely 

 separated lands is insufficient in itself to bring about simi- 

 larity of animals. The tropical parts of Australia, Africa, 

 and South America have very similar climates, but their ani- 

 mals are altogether different. Climate, however, may be 

 an effective barrier to the spread of animals and plants, 

 but its action in this respect 4S entirely negative. 



Two alternative views concerning the origin of new forms 

 of life, animal or vegetable, have been presented. One, the 

 older view, which generally prevailed until the publication 

 of Darwin's Origin of Species, in 1859, was that each kind 

 of animal and plant had been separately created and was, 

 within certain narrow limits, unchangeable and immutable. 



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