212 THE VOYAGE OF H.M.S. CHALLENGER. 
The terminal plate, which is moderately large and broad, is deeply grooved at the 
extremity. 
Colour in alcohol, yellowish white. 
Locality.—Simon’s Bay, Cape of Good Hope. Shallow water, 5 to 20 fathoms. 
Remarks.—The nearest ally of this form appears to be Astropecten serratus, Muller 
and Troschel, from which, however, it may, in my opinion, be distinguished by the char- 
acters of the supero-marginal plates, of the spinulation of the infero-marginal plates, and of 
the armature of the adambulacral plates. The rays also are shorter and broader. 
11. Astropecten zebra, Sladen (Pl. XXXVI. figs. 3 and 4; Pl. XXXIX. figs. 7-9). 
Astropecten zebra, Sladen, 1883, Journ. Linn. Soc. Lond. (Zool.), vol. xvii. p. 261. 
Rays five. R=34 mm.; r=9 mm. R=3°7 ry. Breadth of a ray at the base, 
about 9 mm. 
Rays rather narrow, and although tapering gradually from the base to the extremity, 
the tip is comparatively obtuse. Interbrachial arcs distinctly rounded. 
The paxille of the abactinal area are large, having one to four, or even more, central 
spiniform granules on the tabulum, surrounded by eight to twelve short spinelets in a 
circle on the periphery. A slight prominence is present in the centre of the disk of some 
specimens, but scarcely sufficient to produce a conical peak. In one specimen a slight 
invagination occurs in the centre of the prominence. 
The supero-marginal plates, which are twenty-five in number from the median inter- 
radial line to the extremity, are higher than broad, and have the appearance of forming a 
rounded sloping bevel to the ray, especially in the interbrachial are. The plates are 
uniformly covered with papilliform granules, and bear no spines or tubercles whatever, 
excepting the innermost four plates on each side of the median interradial line. These four 
or five plates are armed with a short, conical, and slightly compressed spinelet, the 
innermost being longest, and the others decreasing in size as they proceed outward. 
The infero-marginal plates are much broader than high, and do not extend beyond the 
superior series, although in large specimens there is a tendency to appear to do so in con- 
sequence of the presence of a slight prominence on the plate on which the lateral spine is 
articulated. There is one lateral spine of moderate length, which tapers throughout, is 
sharply pointed, cylindrical, and very slightly flattened; this is accompanied by a second 
spine, about two-thirds the length of the lateral spine, placed immediately behind and 
close to the aboral side of the plate. Two or three small compressed spinelets are situated 
in line on the aboral side of the plate, that near the inner extremity adjacent to the adam- 
bulacral plates often slightly largest. No other spines are present on the infero-marginal 
plates, which are covered with moderately well-spaced squamules. 
