172 ANELASMA SQUAJJCOLA. 



adductor and of the cirri and tropin, that they are involun- 

 tary, but only that they are in an embryonic condition, 

 for I find in the natatory larva, that all the muscles, with 

 the exception of some connected with the eyes, are simi- 

 larly destitute, and yet perform voluntary movements. # 



Although in the dead state, the aperture of the capitu- 

 lum seems to be always gaping, yet I have little doubt, 

 that the living animal can fold the flexible membrane, 

 like a mantle, round its thorax and cirri, and thus pro- 

 tect, though feebly compared with most Cirripedes, these 

 organs. I suspect that the mouth is always exposed. 



Peduncle. — The membrane of the peduncle is thin j the 

 whole surface is sparingly and quite irregularly studded 

 with minute, much-branched filaments (PL IV, fig. 3, 

 highly magnified) ; these are occasionally as much as Jth of 

 an inch in length ; the degree of branching varies much, 

 but is generally highly complex ; the ordinary diameter 

 of the branches is about o^th of an inch ; their tips are 

 rounded, and even a little enlarged, and frequently torn 

 off, as if they had been attached to or buried in the flesh 

 of the shark, in which the whole peduncle is imbedded. 

 These filaments are formed of, and are continuous with 

 the external transparent membrane of the peduncle, and 

 they contain, up to the tips of every sub-branch, a hollow 

 thread of corium, prolonged from the layer internally 

 coating the whole peduncle. In all other Lepadidse, the 

 peduncle increases in length, chiefly at the summit where 

 joined to the capitulum, and in diameter, throughout 

 nearly its whole length, except close to the base; but, 

 owing to the constant disintegration of the outer surface, 

 the old outside coat does not split in defined lines, like 

 the membrane of the capitulum. In Anelasma, however, 

 owing to the imbedded position of the peduncle, the old 

 outer coats are preserved, the lines in which they have 



* Dr. C. Schmidt in his Contribution to the comparative Anatomy 

 of the Invertebrate animals, &c, (translated in Taylor's Scientific Memoirs, 

 vol. v, p. 1,) says that in young Crustacea, " we find plain primitive fibres, 

 which subsequently acquire the transversely striated aspect." 



