ECHINODERMATA. 259 
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 ali kinds ; their sole occupation 
iseto 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 branchize which in each ray constitute 
two double series of bladders.. The function of circulation is not yet 
R 2 
