158 GENUS — ALEPAS. 



ture, the capitulum must possess considerable powers of 

 contraction. 



The antennae of the larva in the Alepas cornuta and 

 A. minuta have the sucking disc nearly circular, with the 

 spines unusually plain on the distal as well as proximal 

 margin. Basal segment broad, much constricted where 

 united to the disc. The ultimate segment has on the 

 middle of the outer margin, in A. cornuta, two minute 

 spines, which I have not observed in any other cirripede : 

 on the summit there are the usual spines. 



Size. — Three of the species are small. 



Filamentary Appendages. — These are rather small; 

 there is only one on each side, situated on the posterior 

 margin of a slight swelling, beneath the basal articulation 

 of the first cirrus ; and therefore in the position in which 

 the filaments are most constant in Lepas, and where they 

 likewise occur in Conchoderma. 



Body. — The prosoma is either pretty well developed 

 or is small, according as the first cirrus is placed near to, 

 or far from the second cirrus. 



Mouth. — Labrum moderately bullate, with the lower 

 part more or less produced ; crest with blunt, bead-like 

 teeth, and short hairs. 



Palpi (PI. X, fig. 8), acuminated and narrow to an 

 unusual degree. 



Mandibles, with two or three teeth, and the inferior 

 angle acuminated ; the lateral bristles unusually strong, 

 so as to give the main teeth the appearance of being pec- 

 tinated. 



Maxillce, widely notched, with three great upper spines ; 

 the part beneath the notch projecting, and either straight 

 or irregular. 



Outer MaxillcB, with the inner bristles either continuous 

 or divided into two groups : exteriorly there is a smaller 

 or larger prominence, with long bristles. The olfactory 

 orifices are either slightly, or not at all protuberant. 



Cirri. — In the three posterior pair, the segments have 

 their bristles arranged in a transverse row, either in the 



