DISTRIBUTION OF LIFE IN THE OCEAN. 143 



minimum ; the birds are chiefly gulls and ducks, which go 



f ^-^ 



there for the breeding season in the summer, and the reindeer 

 and polar bears are almost sole possessors of the snow and ice- 

 fields ; but this meagreness in the representation of the larger 

 land Mammalia is amply compensated in the numbers of heavy 

 aquatic Mammalia, the whales, walruses, seals, and porpoises of 

 the Arctic seas. 



During the last half-century, since the geographical distribu- 

 tion of animals and plants has become a subject of more careful 

 investigation among naturalists, these broad zones of the earth's 

 surface, with their characteristic populations and vegetation, have 

 been subdivided, according to more limited and special combina- 

 tions of organic forms, into narrower zoological and botanical 

 areas. The application of these results to marine life is however 

 of much more recent date, and indeed it would seem at first 

 sight, as if the water, from its own nature, could hardly impose a 

 barrier so impassable as the land. The localization of the marine 

 faunae and florae is nevertheless as distinct as that of terrestrial 

 animals and plants, and late investigations have done much 

 to explain the connection of this distribution with physical con- 

 ditions. 



A glance at the coast of our own continent, starting from the 

 high north and making the circuit of its shores, from Baffin's 

 Bay to Behring's Straits, will show us to what a variety of physi- 

 cal influences the animals who live along its shores are subjected. 

 On the shores of Baffin's Bay, especially on the inner coast of 

 Greenland, where the glaciers push their way down to the very 

 brink of the water, and annually launch their southward-bound 

 icebergs, we shall hardly expect to find a very abundant littoral 

 fauna. On its western shore, where the ice does not advance so 

 far, and a greater surface of rock is exposed, the circumstances 

 are more favorable to the development of animal life. Here 

 abound the winged Mollusks (Pteropods), often swept down to 

 the coast of Nova Scotia by the cold current from Baffin's Bay ; 

 the " whale feed," as the fishermen call them, because the whales 

 devour them voraciously. Here occur also many compound 

 Mollusks, especially a variety of Ascidians, and the highly colored 

 stocks of Bryozoa. With them is found the Comatula of the 



