114: EVENINGS AT THE inCEOSCOPE. 



portion of the integument proper. I take it to be a 

 film of nincus (composed of deorganized epithelial 

 cells), Avhich is constanth^ 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 tha 

 animal, it is washed away by the motions of the waves. 

 As, however, one film is no sooner removed than 

 another commences 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 cincUdes are not excretorv orifices for the outflow 

 of the respired water, in the manner of the discharging 

 siphon in tlie Bivalve Mollusca: — at least that do 

 current 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 slight- 

 est deviation in the little atom's course could be de- 

 tected. 



That the cinclides are the special orifices through 

 ivhich 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. dlaiithus, somewhat distended, 

 placed in a glass vessel between my e^^e and the sun, 

 t saw, with great distinctness, by the aid of a pocket 



