532 GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 



one group the Opossum Family which is found in 

 America. 



If we look at North America alone, we find ample illus- 

 trations of some of the principles first stated. As a genr 

 eral rule, the animals are specifically different on the two 

 sides of the continent, and in many cases the Rocky 

 Mountains are the line of separation. Some animals, as 

 the Pronghorn, Rocky Mountain Goat, and Rocky Moun- 

 tain Sheep, have not even an analogue in the eastern por- 

 tion of the continent. Even those animals that resemble 

 each other so much that they were formerly regarded as 

 the same in both halves of the continent, are now known 

 to differ specifically from one another. This is true of 

 Mammals and Birds, Reptiles and Fishes, Insects, and the 

 lower forms. 



From the facts stated above, it would seem that climate 

 has no power to mould or shape the species of animals, 

 and the same is true in regard to plants, or to change 

 one species into another. Were it so, any given climate 

 would produce, in the course of time, the same species of 

 animals in all the countries within its limits. But so far 

 from this being the case, we find that, in spite of the in- 

 fluence of climate, animals of the different countries even 

 of the same climatic zone are specifically, if not generi- 

 cally, distinct, and in many cases even family resemblances 

 are wanting. 



Although, through the agency of man, and in many 

 other ways, animals of one region or country have been 

 introduced into another, we are probably not to look to 

 any such accidental operations for an explanation of the 

 distribution of animals into many. well-marked zoological 

 provinces. On the contrary, careful observers have been 

 led to believe that animals as well as plants have been 

 created by an Omniscient Being, in the places, and for 

 the places, which they now occupy. 



