228 SCALPELLUM VULGARE, 



become pressed against the almost parallel branch of 

 the coralline. The corium, at this same period, shrinks, 

 or is absorbed^ and the two cement-ducts come in con- 

 tact with, and adhere to, the inner surface of the outer 

 membrane of the peduncle ; and then, by a process which 

 I do not understand in this or any other Cirripede, 

 apertures are formed both in the ducts and through the 

 membrane, so that the cement passes through, firmly 

 fastening the outer surface of the peduncle with its cal- 

 careous scales and spines, to the coralline. 



The structure of the larval prehensile antennae will be 

 most conveniently described when we come to the Coni- 

 plemental male ; and figures (10 — 12, PL V) will be given. 



Size and Colours. — Montagu states ( c Test. Brit.,' p. 18) 

 that British specimens rarely have a capitulum '62 of an 

 inch in length; I have, however, seen an Irish specimen, 

 '7 long; and several specimens, from the Bay of Naples, 

 •8 long, and including the peduncle, 1*3 in length. The 

 valves in all the specimens are white, and the mem- 

 brane connecting them either nearly white, or dirty pale 

 yellowish, or purplish-brown. Within the sack the 

 corium under the valves is tinted pale purple, and two 

 very faint bands of the same colour can generally be dis- 

 tinguished running down the two sides of the peduncle. 

 Body, coloured yellowish- white, with the upper segments 

 of the pedicels of the cirri, tinted in front with purple. 



Body, much flattened, the prosoma is very little de- 

 veloped ; the mouth placed far from the adductor muscle, 

 and is directed in a remarkable manner towards the 

 ventral surface of the thorax : the first pair of cirri stands 

 far separated from the second pair. 



Mouth. — Labrum with the upper part highly bullate, 

 forming an overhanging projection equalling the longi- 

 tudinal axis of the mouth ; basal margin much produced ; 

 crest with a row of bead-like teeth. 



Palpi rather small, with their external margin straight, 

 and internal margin oblique : the bristles on the two 

 palpi just meet each other. 



