16 LEPADID.E. 



be retracted within the carapace. They consist of three 

 segments : the first or basal one is much larger than the 

 others, and apparently always has a single spine on the 

 outer distal margin. The second segment consists either 

 of a large, thin, circular, sucking disc, or is hoof-like 

 (Tab. V, figs. 5, 10, 11, 12) ; in all cases it is furnished 

 with one or more spines, (seven very long ones in Lepas,) on 

 the exterior-hinder margin. The third and ultimate seg- 

 ment is small ; it is articulated on the upper surface of the 

 disc, and is directed rectangularly outwards ; it is some- 

 times notched, and even shows traces of being bifid ; it 

 bears about seven spines at the end; some of these spines 

 are hooked, others simple, and in Lepas and Conchoderma, 

 two or three are very long, highly flexible, and plumose, 

 a double row of excessively fine hairs being articulated on 

 them. I can hardly doubt that these latter spines, (within 

 which the purple corium could be seen to enter a little 

 way,) floating laterally outwards, serve as feelers. The 

 antenna?, at first, are well furnished with muscles. They 

 serve, in Lepas, according to Mr. King, and in Balanus, 

 according to Mr. Bate, and as I saw myself in another 

 unnamed order, for the purpose of walking, one limb being 

 stretched out before the other ; but their main function 

 is to attach the larva for its final metamorphosis into a 

 Cirripede. The disc can adhere even to so smooth a 

 surface as a glass tumbler.* The attachment is at first 

 manifestly voluntary, but soon becomes involuntary and 

 permanent, being effected by special and most remarkable 

 means, which will be most conveniently described in a 

 later part of this Introduction. I will here only state 

 that I traced with ease the two cement- ducts running 

 from two large glandular bodies, to within the antenna? 

 up to the discs. 



Eyes. — Close behind the basal articulations of the 

 antenna?, the sternal surface consists of two approximate, 

 elongated, narrow, flat pieces, or segments. These 



* Rev. R. L. King. Annual Report of R. Institution of Cornwall, 

 1848, p. 55. 



