Introductory Remarks. 3 



' zoological realms,' of which he recognized 9 for the land and 

 5 for the sea. It is not my i)urpose to discuss the zoological 

 regions of the whole world, hut to lay before yon some of the 

 facts concerned in the distribution of terrestrial animals and 

 l^lants in North America with special reference to the number and 

 boundaries of tlie sub-regions and minor life areas, and to touch 

 upon the causes that have o})erated in their production. 



No phenomenon in the whole realm of nature forced itself 

 earlier upon the notice of man than certain facts of geographic 

 distribution. The daily search for food, the first and principal 

 occupation of savage man, directed his attention to the unequal 

 distribution of animals and ^jlants. He not only noticed that 

 certain kinds were found in rivers, ponds, or the sea, and others 

 on land, and that some terrestrial kinds Avere never seen except 

 in forests, while others were as exclusively restricted to open 

 l)rairies, but he observed further, when his excursions were ex- 

 tended to more distant localities or from the valleys and plains 

 to the summits of neighboring mountains, that unfamiliar fruits 

 and insects and birds and mammals were met with, while those 

 he formerly knew disappeared. 



Thus primeval man, and in truth the ancestors of primeval 

 man, learned by observation the great fact of geographic distribu- 

 tion, the fact that particular kinds of animals and jjlants are not 

 uniformly diffused over the earth, but are restricted to more or 

 less circumscribed areas. 



It will l)e ol)served that two classes of cases are here referred 

 to, namely, (1) eases in which in the same general region certain 

 species are restricted to swamps or lowlands, while others are 

 confined to dense forests or rocky hillsides — differences of station, 

 and (2) cases in which, regardless of ?om^ peculiarities, a general 

 change takes place in the fauna and flora in passing from one 

 region to another, or from low valleys or plains to high moun- 

 tains — geographic differences. The latter class only is here con- 

 sidered. 



Every intelligent schoolboy knows that elephants, lions, 

 giraffes and chimpanzees inhabit Africa ; that orangs and flj'ing 

 lemurs live in Borneo; kangaroos in Australia; the apteryx in 

 New Zealand; the Royal Bengal tiger in India; llamas, chin- 

 chillas and sloths in South America ; the yak in the high table 

 lands of Thibet, and so on. In accordance with these facts 

 naturalists long ago began to divide the surface of the globe into 



