ATTACHMENT. 33 



manner as the valves of the capitulnm : in this genns 

 alone (as already stated,) the calcified scales are moulted, 

 and here alone their edges are serrated. 



The peduncle is lined within by three layers of muscles, 

 longitudinal, transverse, and oblique, all destitute of the 

 transverse striae, characteristic of voluntary muscles ; they 

 run from the bottom of the peduncle to the base of the 

 capitulum, as in Lepas, or half way up it, as in Concho- 

 derma; in Alepas alone they surround the whole 

 capitulum up to its summit. In Lithotrya there are two 

 little, fan-like, transverse muscles (involuntary), extending 

 from the basal points of the terga to a central line on the 

 under side of the carina. The gentle swaying to and 

 fro movements, and the great power of longitudinal con- 

 traction, — movements apparently common, as I infer 

 from facts communicated to me by Mr. Peach, to all the 

 Pedunculata, — are produced by these muscles. The 

 interior of the peduncle is filled up with a great mass of 

 branching ovarian tubes ; but in Ibla and Lithotrya, the 

 upper part of the peduncle is occupied by the animal's 

 body. 



Means of Attachment. — If the peduncle be very care- 

 fully removed (Tab. IX, fig. 7 and Tab. I, fig. 6b), from 

 the surface of attachment, quite close to the end, but not 

 at the actual apex, the larval prehensile antennae can 

 always be found: these have been sufficiently described 

 for our present purpose under the head of the Metamor- 

 phoses ; but I may add, that the diagnostic differences 

 between them in the several genera are briefly given, for 

 a special purpose, in a discussion on the sexes of Scal- 

 pellum at the end of that genus. We have seen in the 

 larva, that the cement-ducts, with their opaque cellular 

 contents, can be traced from within the discs of the 

 antennae to the anterior or lower ends of the two gut- 

 formed bodies, which it can be demonstrated are the 

 incipient ovaria. 



In mature Cirripedes these ducts can be followed, in a 

 slightly sinuous course, along the muscles on each side 



3 



