24 THE MUTUAL DEPENDENCY OF ANIMALS. 



It is by thus associating it with religious sentiment with 

 the presumed immutability and perfection of the present sys- 

 tem that currency has been given to the opinion : but truly 

 the existence of animals and of man is held on no such slight 

 and uncertain tenure, and it has been proved that the ex- 

 tinction of many species has been attended with no ruinous 

 result.* That animals are nevertheless more or less depend- 

 ent on one another is evident: one species may disappear, 

 and its loss be unfelt ; but were the process of extinction to 

 proceed from species to races and families, the resources of 

 some of the remainder must fail, and it is improbable that 

 their constitutions would be pliable enough to accommodate 

 itself without injury to subsistence of a new character. It is 

 in fact the dependency which animals have upon each other 

 for a supply of necessary food, that mainly concatenates the 

 whole, f On contemplating this part of creation, we behold 

 a scene of havoc and devastation perpetually and everywhere 

 going on, so that " there is not," as Smellie has remarked, 

 " perhaps a single species (or family) of animated beings, 

 whose existence depends not, more or less, upon the death 

 and destruction of others." That this order of things, how- 

 ever cruel it may appear to us, is subservient to the good of 

 the whole, cannot admit of any doubt ; and it is my purpose, 

 in the present letter, to convince you by some detail of facts, 

 that molluscous animals in this relation play a not unimport- 

 ant part. But, as it would be tedious to enumerate all or 

 the greater portion of the animals to which they furnish 

 nutriment, we shall confine ourselves to those which possess 

 some peculiar interest, or which minister directly to the luxu- 

 ries or necessities of man. 



To commence with quadrupeds and mammals. It is no- 

 thing surprising that the different species of walrus and nar- 

 whales, inhabitants of ocean, should feed partly or principally 

 on cuttles and shell-fish ; nor that the whale should obtain 

 a large proportion of the nutriment for its huge growth from 

 the myriads of little pteropod Mollusca, which crowd the 

 Arctic seas ; J but perhaps you would not expect to find 

 among molluscous feeders animals which are strictly terres- 

 trial. Yet the ouran-outang and the preacher-monkey, it is 

 said, often descend to the sea to devour what shell-fish they 

 may find strewed upon the shores. The former, according 

 to Carreri Gemelli, feed in particular on a large species of 



* Lyell's Geology, ii. 128. 



t Mr. C. Darwin has some interesting remarks bearing on this question in 

 the Voy. of the Adventure and Beagle, 304-5. 

 Ent. Mag. iii. 433.' 



