with a capitulum under half an inch long. [26] Mr. W. Thompson found that 15 specimens, out of about 200, attached to a vessel which came from New Orleans into Belfast, had their carinas barbed. _Filamentary Appendages_;--never more than two on each side, with sometimes only one developed; of variable length; one seated on the flank of the prosoma, under the first cirrus; the second close under the basal articulation of this cirrus, on the posterior face of a slight swelling: these appendages correspond with _g_ and _h_ in Fig. 4, Pl. IX. _Mouth._--Mandibles (Pl. IX, fig. 5), with, as usual, five teeth, all pointing downwards. Maxillæ (Pl. IX, fig. 9), with the lower step of variable width compared to the two upper steps. _Cirri_; posterior cirri with segments (fig. 26) bearing six pair of spines; intermediate fine spines rather long; first cirrus, anterior ramus longer by only about two segments than the posterior ramus; second cirrus with anterior ramus, with very broad transverse rows of bristles; spine-bearing surfaces considerably protuberant; caudal prominences smooth, rounded. _Size._--The largest specimen which I have seen had a capitulum two inches in length; the longest, including the peduncle, was sixteen inches. _Colours._--Calcareous valves already described. Edges of the orifice bright scarlet orange; basal edges of the scuta, and sometimes of all the valves, with a torn border of orange membrane. Interspaces between the valves dull orange-brown. Peduncle darkish purplish-brown, with the lower part sometimes pale; chitine membrane itself tinted orange; in young specimens, peduncle pale, the colour first appearing in the uppermost part, close under the capitulum; this upper part is often darker than the other parts, and never orange-coloured, as in _L. Hillii_ and _L. anserifera_. _Sack_ internally dark purplish lead-colour, sometimes with a tinge of orange, darkest under the growing edges of the valves; body of animal pale purplish lead-colour. The four posterior cirri blackish purple; the second, and often the third cirrus, appear as if the colour had been laterally abraded off; these latter cirri have sometimes a tinge of orange. In very young specimens, the cirri are only barred with purple. The ova and the contents of the ovarian tubes are of a beautiful azure blue, becoming yellow in spirits.