OCEAN LIFE. 21 



year, or perhaps even longer, in a vessel of sea-water, without any 

 visible food ; but when food is offered, one of them will devour a 

 crab, as large as a hen's egg or two muscles in their shells ; in a 

 day or two, the shells are voided through the mouth, perfectly 

 cleared of the soft parts which they contained. The tentacles 

 have the same prehensile power as those of the Hydrce, a power 

 which depends on the presence of projectile barbed weapons, 

 ordinarily coiled in elastic cells. These organs are coiled in in- 

 conceivable multitudes imbedded in the tissues of the tentacles, 

 of the lips, of the stomach, of the frilled ovarian bands, and 

 especially, in some species, in long threads which are protruded 

 from pores in the integuments of the body. The structure of 

 these weapons is as follows : each consists of an oval or elliptical 

 sac of transparent membrane, within which is seen a thread 

 coiled up, and in some instances, an oblong or lozenge-shaped 

 chamber. At the pleasure of the animal, or under the stimulus 

 of pressure, the thread is shot forth from one end of the cell 

 with great force, until it extends to a length of from twice to 

 fifty times that of the cell. "When fully extended, it seems that 

 the thread is but a continuation of the cell itself; that when 

 it was dormant, it was turned in ; and that in the process of ex- 

 pulsion, every part of its length has actually been turned inside 

 out, like the finger of a glove. Sometimes the thread appears 

 simple, but in those cases, in which a chamber appeared with- 

 in the cell, it is furnished with an armature of barbed 

 threads, which, after the expulsion, project from the sides of 

 the thread in all directions. The propulsion of the thread 

 is sufficiently forcible to enable it to enter the tissues of 

 other animals, and the barbed structure enables the weapon to 

 retain its hold in the flesh, which facts warrant the presumption 

 that a highly poisonous fluid is at the same time injected, capable 

 of arresting and destroying the animal life. Although the prey 

 of the Actinia usually consists of Crustacea, the smaller mollusca 

 and star fishes ; it is sometimes of much greater dimensions. 

 Dr. Johnson observes, "I had once brought me a specimen of 

 Actinia crassicornis, that might have been originally, two inches 

 in diameter, and that had somehow contrived to swallow a valve 

 of the great scallop (Peeten maximus) of the size of an ordinary 



