364 GE1STEEAL LAWS OF DISTEIBUTION. 



are alike, because some of the sea-weeds found on both their 

 shores are the same. 



580. There is an evident relation between the fauna of 

 any locality and its temperature, although, as we shall here- 

 after see, similar climates are not always inhabited by similar 

 animals. Hence the faunas of the two hemispheres have been 

 distributed into three principal divisions, namely the arctic, 

 the temperate, and the tropical, in the same manner as we 

 have arctic, temperate, and tropical floras ; hence, also, ani- 

 mals dwelling at high elevations upon mountains, where the 

 temperature is much reduced, resemble the animals of colder 

 latitudes, rather than those of the surrounding plains. 



581. In some respects the peculiarities of the fauna of a 

 region depends upon its flora, at least so far as land animals 

 are concerned ; for herbivorous animals will exist only where 

 there is an adequate supply of vegetable food ; but, taking the 

 terrestrial and aquatic animals together, the limitation of a 

 fauna is less intimately dependent on climate than that of a 

 flora. Plants, in truth, are for the most part terrestrial (marine 

 plants being relatively very few) while animals are chiefly 

 aquatic. The ocean is the true home of the animal kingdom ; 

 and while plants, with the exception of the lichens and mosses, 

 become dwarfed or perish under the influence of severe cold, 

 the sea teems with animals of all classes, far beyond the ex- 

 treme limit of flowering plants. 



582. The influence of climate, in the polar regions, acts 

 merely to induce a greater uniformity in the species of animals. 

 Thus, the same animals inhabit the northern polar regions of the 

 three continents ; the polar bear is the same in Europe, Asia, 

 and America, and so are also a great many birds ; in the tempe- 

 rate regions, on the contrary, the species differ on each of the 

 continents, but they still preserve the same general features ; 

 the types are the same, but they are represented by different 

 species. In consequence of these general resemblances, the first 

 colonists of New England erroneously applied the names of 

 European species to American animals. Similar differences are 

 observed in distant regions of the same continent, within the 

 same parallels of latitude. The animals of Oregon and of 

 California are not the same as those of New England. The 

 difference, in certain respects, is even greater than between 

 the animals of New England and Europe. In like manner, 



