SEA-ANEMONES: THEIR WEAPONS. 861 



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 process 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 current con- 

 stantly, 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 re- 

 covered, 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. dianthiis, 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 



