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Show 96 ZOOLOGICAL COLLECTIONS MADE DURING [Jan. 4, marginal ossicles, in both upper and lower series, on the sides of arm ; at the apex of the angle an azygos triangular " anticlinal" plate, as in Pentagonaster singularis. The plates vary considerably in the extent to which they are covered with granules, the more distal marginal ossicles having the granules confined to their borders, while in the more internal they are better-developed. The infero-marginal plates are richly covered with spiny tubercles, which are developed into distinct spines, set in tufts, on the ventral ossicles of the disk. On the borders of the ambulacral groove there is a transverse row of three or four well-marked spines ; at the oral angle one spine is elongated and has a glassy appearance, so that it is much more conspicuous than the corresponding spine in C. emma. Abactinal surface blackish brown, with here and there lighter spots; marginal ossicles all white at the apex of the arm ; but some of the more internal are of a lightish brown ; ventral surface light brown. This species is an ally of the Calliderma emma of Dr. Gray, which has been so beautifully figured by him in his * Synopsis ' (pi. xv.). One specimen from Sandy Point, 9-10 fathoms; bottom, sand. A somewhat younger specimen of this species was collected by Dr. Cunningham in the Straits of Magellan. CYCETHRA, nov. gen. It seems to be necessary to establish a new genus for a specimen which was taken in Trinidad Channel, and which, though generally Goniasterid in character, seems, and that more especially at first sight, to present a combination of characters. The ambulacral grooves are exceedingly narrow, the actinostome small, not widely open, the modified spines of the mouth-organs generally Goniasterine in arrangement; the ventral intermediate plates continuous, but not imbricated, bearing short spines, which in character and arrangement recall the same parts in Asterina. Marginal plates almost completely confined to the sides of the arm and disk ; the ventro-marginal plates only just appearing on the actinal surface, and the dorso-marginal on the abactinal only near the tip of the arm; the plates are separated one from the other by a horizontal as well as by vertical grooves. The whole of the abactinal surface is covered with closely packed small ossicles, among which there are no pore-areas. The central disk is large ; the arms rather short and slender. No pedicellariae. CYCETHRA SIMPLEX, sp. n. (Plate IX. figs. 5, 6.) The following appear to be the specific characters of the specimen obtained:-Adambulacral spines in a single row, not especially subequal, diminishing in size as they pass to the apex of the arm. The spines of both surfaces are short, blunt, almost granular; the marginal plates, with the exception of those near the apex of the arm, are distant almost their own breadth from one another. The ossicles of the abactinal surface are small; and their granules can hardly be said to be produced into spines. The ocular plate is large and white ; the madreporic plate is small and white, rather deeply sunken, |