_General Appearance._--This and the two following species come so close in general appearance to the last, that it will be quite superfluous to do more than describe the few points of difference. The shell and basis are generally quite as much elongated as in the last species, and sometimes much more so, owing to the carinal end (fig. 4 _a_), with the corresponding portion of the basal cup, being produced like the rostral end, into a flattened, sharp point: I have seen a specimen in this state .9 of an inch in length, and only .25 in breadth in the broadest part. In many specimens, however, the shape is exactly as in _B. calceolus_; but the rostrum seems less usually furrowed from clasping the stem of the Gorgonia. The colour is paler, pinker, and more distinctly striped longitudinally than in _B. calceolus_; I have, however, seen some not-striped, purple specimens (and one transversely freckled with white) from the West Indies. The parietes are strongly-ribbed internally, and are not permeated by pores. The radii have their sutural edges crenated. The basal cup is permeated by pores. The _Scutum_ differs from that in the last species, only in the pit for the lateral depressor muscle, being much shallower, and less defined, and in the apex being truncated. The _Tergum_ is remarkable from its broad, square, truncated summit, which underlies the whole broad apex of the scutum: the square summit of the tergum is formed by a great and peculiar development of the uppermost part of the articular ridge. The spur is a little narrower than in _B. calceolus_. _Mouth_: on the crest of the labrum there are two teeth on each side of the central notch. The mandibles have five teeth, of which the two lower are very small. The maxillæ show a trace of a notch under the upper large pair of spines; near the inferior angle there are two long spines. _Cirri_: in the first pair, one ramus is nearly twice as long as the other: the segments are not very protuberant. There is a sharp point at the dorsal basis of the penis. The branchiæ are of moderate size, and plicated on one side. 12. BALANUS CYMBIFORMIS. Pl. 3, fig. 5 _a_, 5 _b_. _Parietes and basis not porose. Scutum and Tergum with very small articular ridges. Tergum broad, almost equilateral._ _Hab._--Attached to a Gorgonia, Tubicoreen, near Madras, (Dr. Johnston). Hab. unknown, Mus. Cuming.