SEA- ANEMONES I THEIR WEAPONS. 361 



a hemispherical bladder, in which state it remained as 

 long as I looked at it. At the same time the outline of 

 the cinclis itself was sharp and clear, when brought into 

 focus further in. The film, whatever it be, is superficial, 

 and does not appear to be a portion of the integument 

 proper. I take it to be a film of mucus (composed of 

 deorganised epithelial cells), which is constantly in pro- 

 cess of being sloughed from all the superficial tissues in 

 this tribe of animals, and which continues tenaciously to 

 invest their bodies, until, corrugated by the successive 

 contractions of the animal, it is washed away by the 

 motions of the waves. As, however, one film is no 

 sooner removed than another begins to form, one would 

 always expect external pores so minute as these to be 

 veiled by a mucus-film in seasons of rest. 



The pressure of this film is sufficient evidence that 

 the cinclides are not excretory orifices for the outflow of 

 the respired water in the manner of the discharging 

 siphon in the Bivalve Mollusca : — at least that no cur- 

 rent constantly, or even ordinarily, passes through them. 

 I have watched them continuously for periods sufficient 

 to detect such discharge if it were periodic. On one 

 occasion (viz., that in which the film was protruded like 

 a blown bladder) a minute Infusorial animalcule chanced 

 to pass across, close to the surface of the film : this would 

 have been a decisive test of the existence of a ciliary 

 current ; but not the slightest deviation in the little 

 atom's course could be detected. 



That the cinclides are the special orifices through 

 which those missile weapons, the acontia, are shot and 

 recovered, rests not merely on the probability that arises 

 from the co-existence of the two series of facts I have 

 above recorded, but upon actual observation. In a rather 

 large S. dianthus, somewhat distended, placed in a glass 

 vessel between my eye and the sun, I saw, with great 

 distinctness, by the aid of a pocket-lens, many acontia 



