_Fifth and Sixth Cirri._--These resemble each other, and have their inner or posterior rami in an almost rudimentary condition. In the sixth cirrus (Pl. X, fig. 28) the outer ramus (_a_) has actually sixty-three segments, whereas the rudimentary ramus (_k_) has only eleven, nearly cylindrical segments. These are furnished with extremely minute spines, of which those on the dorsal face are longer than those on the anterior face; the spines on the summit of the terminal segment are the longest; the segments are not half as thick as the normal ones in the outer ramus. The rudimentary ramus is only one seventh part longer than the pedicel which supports both it and the normal ramus. In the fifth cirrus, the rudimentary ramus is rather longer, and has thirteen segments, resembling those in the rudimentary ramus of the sixth. In the fourth cirrus there is no trace of this peculiar structure, the rami being equal in length and strength. The two rudimentary rami on each side are nearly straight, and seem incapable of movement; they project out behind the normal rami, and closely resemble in general appearance, the two caudal appendages; hence this cirripede, at first sight, appears to be six-tailed. _Pedicels of Cirri._--The pedicel of the first pair is very short; that of the second is the longest; those of the posterior cirri decreasing in length. Upper segments short; lower segments in the second, third and fourth cirri, irregularly and rather thickly clothed with bristles, but in the fifth and sixth cirri, there is a regular double row of main spines, with some minute intermediate ones: hence there is a difference, both in the rami and in the pedicels, between the fourth cirrus and the fifth and sixth, and this is a unique case. On the dorsal surface of the pedicel of the second cirrus, there is a tuft of much feathered fine spines. _Caudal Appendages._--Each consists of eight much tapering, very thin segments, furnished with a few short simple spines round their upper margins, and with a longer tuft on the terminal short segment; basal segments twice as thick as the middle ones. In length, these caudal appendages equal the pedicels of the sixth pair of cirri, and are a very little shorter than the rudimentary rami of these same cirri. _General Remarks._--Having examined this species first in the genus, I fully anticipated that the very remarkable character of the inner rami of the fifth and sixth cirri being rudimentary, and serving the same function (if any) with the caudal appendages, would have been generic; but this is not the case, for _Alepas cornuta_ cannot be separated from _A. minuta_ without violating a clear natural affinity. 4. ALEPAS TUBULOSA. Quoy et Gaimard. Voyage de l’Astrolabe, Pl. xciii, fig. 5, 1834. _A. aperturâ parvâ prominente et tubulosâ: scutis et prominentiis secundùm marginem carinalem, nullis._ Orifice small, tubular, protuberant; capitulum without horny scuta or projections along the carinal margin.