_Capitulum_ globular, slightly flattened, smooth, translucent, entirely destitute of valves; orifice slightly projecting or tubular, parallel to the longitudinal axis of the peduncle, with the edges sinuous; it appears more tubular than it really is, from the convexity of the part of the capitulum immediately beneath the orifice. Three small, flexible, horny, irregular prominences project from the carinal margin; one at the bottom of the capitulum; a second about half-way up it; and a third generally close to the orifice; but their positions vary a little, and the prominences vary still more in shape and size, being either rounded and very small, or much flattened and considerably prominent; they are imperforate; in the membrane under them a few tubuli may be seen, which are not elsewhere visible; their summits are roughened with very minute points and beads of chitine; others, still minuter, are scattered over the whole capitulum. _Peduncle_ short, narrower than the capitulum, into which it insensibly blends; strongly wrinkled; surface of attachment wide; position with respect to the branches of the coralline, various. _Size and Colour._--The largest specimen, including the peduncle, was half an inch in length, and 3/10ths of an inch across the capitulum; colour, after having been long in spirits, brownish-yellow. _Filamentary Appendages_, one on each side, short, tapering and pointed; seated on the posterior margin of a slight swelling beneath the basal articulation of the first cirrus; they are about equal in length to the pedicels of this cirrus. The _Mouth_ is directed abdominally; labrum much produced downwards, so as to be far separated from the adductor muscle; moderately bullate, forming about one third of the longitudinal axis of the entire mouth; upper part forming a slightly overhanging prominence; crest with a row of blunt, bead-like teeth, and externally to them there are numerous curved short bristles. _Palpi_ (Pl. X, fig. 8,) unusually narrow, a little hollowed out along their inner margins; pointing towards the adductor muscle; thickly covered with doubly serrated bristles. _Mandibles_, with either two or three teeth; inferior angle narrow and tooth-like; both sides covered with strong bristles or spines, projecting beyond the toothed edge. _Maxillæ_, with two large upper spines, and a third rather distant from them; beneath these, there is a wide notch or hollow; inferior part square, projecting, bearing six pair of moderately long spines, (of which the central one is the longest,) mingled with finer ones. _Outer Maxillæ_, with a semicircular outline; the serrated bristles in front are divided into two groups; externally there is a rounded and very considerable projection covered with long bristles. Olfactory orifices slightly prominent, approximate, seated within and just beneath the rounded projections at the base of the maxillæ. _Body._--Prosoma little developed; thorax small.