96 ZOOLOGICAL COLLECTIONS MADE DURING [Jail. 4, 



marginal ossicles, in both upper and lower series, on the sides of each 

 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 CaUlderma 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; tl- 1 veutro-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 pedicellarise. 



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, 



