1 

 ADDRESSES AND COMMUNICATIONS. 



THE PRINCIPLES OF ZOOGEOGRAPHY.* 

 BY THEODORE GILL. 



Zoogeography, or the science of the geographical distribution of 

 animals, may be said to have originated with the illustrious French 

 naturalist of the last century, who inaugurated the era of philo 

 sophical zoology in about the same degree as Linnaeus did that of 

 systematic zoology, and who is also well known as the antagonist and 

 rival of the great Swede. Many of the facts that are the bases of 

 its propositions had indeed been known before the time of Buffon, 

 but the relations of those facts to each other, and to the general 

 doctrine of science, had either been entirely overlooked or were 

 vaguely appreciated. 



It is Buffon who is to be credited with having first promulgated 

 precise generalizations respecting the geographical distribution of 

 animals. Buffon, in this respect, not only advanced much beyond 

 his predecessors, but leaped at once to a position which some of the 

 the more pretentious naturalists of our own times have failed to 

 attain. In brief, he recognized (i) that the inhabitants of the 

 tropical and southern portions of the old and new worlds were 

 entirely different from each other ; (2) that those of the northern 

 portions of the two were, to a considerable extent, identical ; and 



* Annual presidential address delivered at the Third Anniversary Meeting of the 

 Society, January 19, 1883, in the lecture room of the U. S. National Museum. 



In the present address, previous contributions by the author to Zoogeography 

 the article " Zoological Geography " in Johnson's New Universal Cyclopaedia, and 

 a review of Wallace's " Geographical Distribution of Animals," published in " The 

 Nation " for July 12 and 19, 1877, and republished in " Field and Forest," (vol. 

 iii, pp. 69-74, 78-80, 98-101,) have been borrowed from. 



