542 LEPADID^. 



the ordinary structure : both segments are destitute of 

 bristles. There are two short rami, being about one 

 third of the length of the pedicel : they are directed either 

 in the line of the pedicel, or more commonly posteriorly, 

 that is towards the other cirri, and therefore in an unusual 

 direction. The anterior ramus is generally rather longer 

 and thinner (as is commonly the case with other Cirripedes) 

 than the posterior ramus ; but there is some variation in 

 this respect. On neither ramus is there any trace of the 

 ordinary articulations : both are thickly clothed with fine 

 bristles, which are singular from being thickened in their 

 lower parts, and plumose, like a feather. These cirri have 

 some resemblance, as remarked by Mr. Hancock, to a pair 

 of pincers ; but they cannot act as such ; they serve, I 

 believe, as brushes. Delicate muscles, transversely striated, 

 enter and are attached within both rami and within both 

 segments of the pedicel, on the usual type, showing that 

 these organs (if there had been any doubt) are truly cirri. 



The fifth and sixth pairs of cirri (fig. 13, ?i, o) are almost 

 exactly alike : they are of very small size : each cirrus con- 

 sists of four segments : the lower or basal segment is broad, 

 with a few minute bristles scattered on its inner surface : 

 the second segment is also broad, but shorter, with a few, 

 generally hooked bristles, in two short irregular rows, in 

 the upper part : these two segments answer to the two 

 segments of the pedicel of ordinary cirri. The third seg- 

 ment is thinner and longer than the second ; it bears two 

 or three longitudinal rows of bristles, most of which are 

 neatly hooked at the point ; its upper end is surrounded 

 with a circle of bristles. The fourth and terminal seo*- 

 ment is short, thin, and simple, with only a few bristles at 

 the apex. These two upper segments are bent a little in- 

 wards; they answer to one of the two normal rami of 

 ordinary cirri. The third segment does not stand exactly 

 on the middle of the summit of the second segment, — the 

 posterior corner of the latter being occupied by a very 

 curious, convex, oblong, rather hard (especially in the lower 

 part), protuberant cushion (as called by Mr. Hancock) or 

 button (fig. 9, c), transversely wrinkled by fine, distinctly 

 crenated ridges. This button presents a considerably dit- 



