PROBOSCIS OF CARNIVOROUS GASTEROPODS. 501 



exceedingly voracious, and, when it gets hold of a 

 neighbouring mollusk, seldom leaves it without eating 

 it up. We have seen a Purpura devour a Periwinkle 

 in the course of an afternoon, when placed in the 

 same vessel of sea-water, a feat which it readily 

 accomplishes ; first, by means of its proboscis, drilling 

 a hole through the shell of its victim, and then 

 quietly and leisurely proceeding to eat the poor ani- 

 mal out of house and home. 



The proboscis, by the instrumentality of which this 

 is performed, is contrived with marvellous artifice : 

 it is not simply provided, like that of the elephant, 

 with the means of flexure and extension, but it can be 

 entirely retracted into the body, by drawing itself 

 into itself in such a manner, that that half of it which 

 forms its base, contains and encloses the half nearest 

 the point ; and it can again be protruded from its 

 sheath thus formed, by unfolding like the finger of a 

 glove, or like the horns of the gar den- snail. 



The boring apparatus is situated at the extremity 

 of this strange organ, and is a formidable instrument, 

 armed with hooked and very sharp spines. It 

 is supported by two long cartilaginous levers, the 

 extremities of which form a pair of lips that can be 

 separated or approximated, or made to move upon 

 each other by the mass of muscles wherein they are 

 imbedded, in such a manner that the spines covering 

 them are alternately depressed and elevated ; so that, 

 by a repetition of these movements, the hardest shells 

 are soon perforated, as by the action of a file. 



No drill could do its work more cleanly, or more 

 efficiently ; and admission being once obtained by this 



