DISTRIBUTION OF LIFE IN THE OCEAN. 141 



DISTRIBUTION OF LIFE IN THE 



OCEAN. 



WE have seen that while our bay is rich in certain species, it is 

 wholly deficient or but scantily supplied with others, and that 

 the character of the animals inhabiting its waters is more or less 

 directly connected with general physical conditions. Such an 

 area, limited though it be, gives us some insight into the laws 

 which, in their wider application, control the distribution of ma- 

 rine life along the shores of the most extensive continents. The 

 coast of Massachusetts, taken as a whole, is like that of New 

 England generally, a rocky coast ; yet it has its sandy and muddy 

 beaches, and though it lies for a great part open to the sea, it has 

 nevertheless its sheltered harbors, its quiet bays and snug re- 

 cesses. 



A comparison of these limited localities with far more exten- 

 sive reaches of shore, where similar physical conditions prevail, 

 shows that they reproduce, in fainter and less various characters 

 of course, in proportion to their narrower boundaries, but still 

 with a certain fidelity, the same combinations of animal and 

 vegetable life. In other words, a sandy beach, however small, 

 gives us some idea of the nature of the animals we may look for 

 on any sandy coast, as, for instance, clams of various kinds, 

 razor-shells, quahogs, snails, <fcc., creatures who can penetrate 

 the sand, drag themselves through it or over it, leaving their 

 winding trails as they go, and to whom the conditions prevailing 

 in such spots are genial. So the narrowest mud flat on the sea- 

 shore or muddy beach will give us the same dead and inanimate 

 aspect which characterizes a more extensive coast of like charac- 

 ter, where the gases always generated in mud are deadly to 

 many kinds of animals, and the beings who find a home there 

 are of closely allied species, chiefly a variety of worms, who bur- 

 row their way into the mud, and seem to court the miasma so 



