ECHINODEKMATA. 265 



fold of its internal membrane ; the first chamber, thus limited, appears 

 to be more especially devoted to the transformation of the elementary 

 matter into a liquid paste, which passes, in small portions, into the 

 upper chamber. This is continued upward through a small intestine, 

 and communicates laterally with five cylindrical prolongations, which 

 each divide themselves again into two much elongated tubes, furnished 

 with a double series of hollow branches, each terminating in a cul- 

 de-sac." These organs advance into the interior of the rays or arms 

 of the Asterias. 



Imagine, then, an animal bearing digestive tubes in its arms the 

 same organ serving for digestion and progression. "What lessons in 

 economy does not the study of nature teach us ! The products of 

 digestion find an absorbent surface of great extent in the rays of the 

 Asterias. They ought necessarily to pass rapidly from it into the 

 circumjacent nourishing fluid. 



The star-fishes are very voracious ; they even attack mollusks which 

 are covered with shells. M. Pouchett mentions having taken eighteen 

 specimens of Venus intact, each being six lines in length, from the 

 stomach of one large Asterias which he dissected upon the shores of 

 the Mediterranean. It is now even said that the star-fishes eat many 

 oysters. 



Ancient naturalists were not ignorant that the star-fish was capable 

 of eating oysters ; but they believed that they waited for the moment 

 when the bivalve would open its valves to introduce one of their rays 

 into the opening. They imagined that having thus put one foot into 

 the other's domicile, they soon put four, and finished by reaching and 

 devouring the savoury inhabitant 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 Kymer 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 Asteria then inverts its stomach, 



