ATTACHMENT. 37 



species, which live attached to corallines, the cement 

 soon ceases to debouch from the antennse, but instead, 

 bursts through a row of orifices on the rostral margin of 

 the peduncle (PL IX, fig. 7), by which means this margin 

 is symmetrically fastened down to the delicate, horny 

 branches of the zoophyte. In Pollicipes, the two cement- 

 ducts, either together or separately (PL IX, fig. 2, 2 a') t 

 wind about the bottom of the peduncle in the most 

 tortuous course, at each bend pouring out cement through 

 a hole in the membrane of the peduncle. In Ibla the 

 lower part of the peduncle is internally filled by cement, 

 and thus rendered rigid. In Lep as fascicular is a vesicular 

 ball of cement surrounding the peduncle is thus formed 

 (PL I, ^g. 6), and serves as a float ! All these curious, 

 special adaptations are described under the respective 

 genera. How the cement forces its way through the 

 antenna?, and often through apertures in the thick mem- 

 brane of the peduncle, I do not understand. I do not 

 believe, though some appearances favoured the notion, 

 that the duct itself debouches and divides, at least this 

 is not the case in Coronula, but only that the internal 

 chord of cellular matter thus acts and spreads itself out ; 

 nor do I understand how, when the antennae and imme- 

 diately adjoining parts are once cemented down, any more 

 cement can escape ; yet this must take place, as may be 

 inferred from the breadth of the cemented, terminal por- 

 tion of the peduncle in Lepas and Conchoderma ; and 

 from the often active condition in old individuals of the 

 cementing organs. 



I have entered on this subject at some length, (and I 

 wish I had space for more illustrations,) from its offering, 

 perhaps, the most curious point in the natural history of 

 the Cirripedia. It is the one chief character of the Sub- 

 class. I am well aware how extremely improbable it 

 must appear, that part of an ovarian tube should be con- 

 verted into a gland, in which cellular matter is modified, so 

 that instead of aiding in the development of new beings, 

 it forms itself into a tissue or substance, which leaves the 



