THE DISTRIBUTION OF ANIMALS. 373 



gonia ; the Musk - rat, from the Arctic Ocean to Florida ; 

 the Ermine, from Behring's Straits to tlie Himalayas ; and 

 the Hippopotamus, from the Nile and Niger to the Orange 

 River."' 



Frequently, species of the same genus, living side by 

 side, are widely different, while there is a close resem- 

 blance between forms which are antipodes. The Mud-eel 

 of South Carolina and Menobranchus of the Northern 

 States have their relatives in Japan and Austria. The 

 American Tapir has its mate in Sumatra ; the Llama is 

 related to the Camel, and the Opossum to the Kangaroo. 



The chief causes modifying distribution are tempera- 

 ture, topography, ocean and wind currents, humidity and 

 h'ght. To these may be added the fact that animals are 

 ever intruding on each other's spheres of existence. High 

 mountain -ranges, wide deserts, and cold currents in the 

 ocean are impassable barriers to the migration of most 

 species. Thus, river- fish on opposite sides of the Andes 

 differ widely, and the cold Peruvian current prevents the 

 growth of coral at the Galapagos Islands. So a broad 

 river, like the Amazons, or a deep, narrow channel in the 

 sea, is an effectual barrier to some tribes. Thus, Borneo 

 belongs to the Indian region, while Celebes, though but a 

 few miles distant, is Australian in its life. The faunae of 

 North America, on the east coast, west coast, and the open 

 plains between, are very different. 



Animals dwelling at high elevations resemble those of 

 colder latitudes. The same species of Insects are found 

 on Mount Washington, and in Labrador and Greenland. 



The range does not depend upon the powers of loco- 

 motion. The Oyster extends from Halifax to Charles- 

 ton, and the Snapping -turtle from Canada to the equa- 

 tor ; while many Quadrupeds and Birds have narrow hab- 

 itats. 



The distribution of any grroup is qualified by the nature 



