482 PHYSIOLUGY AND MORPHOLOGY OF ANIMALS. 



leave the coast. The icy-cold waters coming out of 

 Baffin's Bay hug the New England coast as far as Cape 

 Cod, b, giving it its peculiarly harsh climate, and then 

 disappear and become a deep current. Thus the sub- 

 tropical fauna is carried beyond its limits to Cape Hat- 

 teras, while the arctic shore fauna is carried beyond its 

 natural limits as far south as Cape Cod, making three 

 sharply defined shore faunas. 



Continental Shore Faunas. — The richest marine 

 faunas are along the shores of continents. The deep sea 

 is an impassable barrier to these. Therefore the faunas 

 along the two shores, European and American, of the 

 Atlantic are almost wholly different. The continent 

 itself is, of course, a still more effectual barrier, and 

 therefore our Atlantic shore species and Pacific shore 

 species are wholly different. 



Pelagic Fauna. — Many marine species swim or 

 float freely in the open sea, and are much more widely 

 diffused,, being limited by temperature alone. These 

 are called pelagic species. 



Abyssal Fauna. — Again, certain species live only 

 at very great depths. These are abyssal species. 



Special Cases. — There are special cases here also 

 — that is., the species found along the shores of iso- 

 lated islands, as about Australia, Madagascar, Gala- 

 pagos, etc. 



Primary Divisions of Land Faunas.— Thus, then, 

 organic forms are limited in range in every direction by 

 many kinds of physical conditions. They are limited 

 north and south by temperature, and in all directions by 

 barriers such as mountain chains, deserts, and oceans. 

 Besides these, climate and soils limit especially plants, 

 and these limit animals. Thus the whole earth is di- 

 vided into a few great primary fauna/ regions, and these 

 are subdivided into provinces, etc. Many schemes of 



