ECHINODERMATA. 



having thus put one foot into the other's domicile, they soon put the 

 other four, and finished by reaching and devouring the savoury inhabi- 

 tant of the shell. Modern observations have modified the ideas of 

 former naturalists upon this point. In order to obtain possession 

 of and swallow an oyster, it appears that the star-fish begins its 

 approaches by bringing its mouth to the closed edges of the oyster- 

 shell ; this done, with the assistance of a particular liquid which its 

 mouth secretes, it injects a few drops of an acrid or venomous liquid 

 into the interior of the oyster-shell, which forces it to open its valves. 

 An entrance once obtained, it is not long before it is invaded and 

 ravaged. Professor Rymer Jones gives another explanation of the 

 transaction. According to this naturalist the oyster is seized between 

 the rays of his ravisher, and held under his mouth by the aid of his 

 suckers ; the Asterias then everts its stomach, according to the pro- 

 fessor, and envelopes the entire oyster in its inmost recesses, while, 

 doubtless, distilling a poisonous liquid. The victim is thus forced to 

 open its shell, and becomes the prey of the enemy which envelopes it. 



Whatever may be the modes of procedure employed by the star- 

 fish, it is now clearly ascertained, however incredible the fact may at 

 first appear, that it swallows oysters in the same manner as is prac- 

 tised by human beings at the oyster shop. 



This little being, formed of five arms and without any other 

 apparent member, accomplishes a work which man, unaided, is quite 

 unable to execute it opens an oyster without an oyster-knife. If 

 reasoning man had no other means of nourishment than oysters, and 

 was without a knife to open them, it is very certain that with all 

 his genius he would be puzzled how to get at the inaccessible and 

 savoury bivalve so obstinately closed against him. 



The star-fish devours dead flesh of all kinds ; their sole occupation 

 is to feed themselves, and they keep up an incessant and active chase 

 after all sorts of decaying animal matter. The Asterias thus perform 

 in the bosom of the sea the same part that certain birds and insects 

 play on shore ; they are its scavengers, and feed their bodies upon 

 the carcases of animals which, if abandoned to the action of the 

 elements, would become a cause of infection. 



In the same manner that certain animals render the air healthy, 

 the Asterias helps, on a considerable scale, to keep the sea which 

 shelters it in a pure and healthy state. Zoologists are not agreed 

 upon the manner in which respiration is effected in the star-fishes. 

 Nevertheless they think that the principal part in this phenomenon 

 devolves upon the subcutaneous branchiae which in each ray constitute 

 two double series of bladders. The function of circulation is not yet 



