228 THE VOYAGE OF H.M.S. CHALLENGER. 
Simon's Bay, Cape of Good Hope. (Depth and conditions not recorded.) 
Remarks.—This form is very nearly allied to the North-Atlantic species Psilaster 
andromeda. It may be distinguished by the infero-marginal plates at the base of the 
ray having three or four small flattened spinelets grouped in a slightly oblique series near 
the aboral end of the lateral margin; by the inner pair of mouth-spines being conspicuously 
larger than the rest ; and by the supero-marginal plates not encroaching conspicuously on 
the abactinal area on the outer part of the ray. 
3. Psilaster cassiope, nu. sp. (Pl. XLI. figs. 1 and 2; Pl. VIL. figs. 9 and 10). 
Rays five. R= 63 mm.; 7 =165mm. R<4r. Breadth of a ray near the base 
(between the third and fourth supero-marginal plates), 14°5 mm. 
Rays elongate and tapering ; attenuate towards the extremity but with the breadth 
diminishing very slightly along the inner half of the ray. Lateral walls rather high, well 
and equally rounded towards the abactinal and actinal surfaces, but nearly straight and 
vertical between these curves. Abactinal and actinal areas subplane, giving the rays a 
more or less depressed conico-cylindrical form. Interbrachial ares acutely but distinctly 
rounded. 
The abactinal paxillar area of the disk and rays is covered with numerous small and 
closely crowded paxillz. These are low and of uniform height throughout, and the larger 
ones consist of ten to sixteen very short, thick, papilliform spinelets, with one to three 
irregularly central, the whole forming a compact group, and looking more like rounded 
granules than papille. Excepting upon the central area of the disk, and along a narrow 
band-like strip in the median dorsal line of the rays, the paxille are arranged in very distinct 
and conspicuous transverse series, each series distinctly spaced from its neighbours, and 
with the paxille slightly elongate in the direction of the axis of the ray. The paxillee 
diminish slightly in size as they approach the margin, and also in the central area of the 
disk. 
The supero-marginal plates, thirty in number from the median interradial line to the 
extremity, form a broad and conspicuous border to the disk and rays. Midway along the 
ray the breadth is subequal to that of the intermediate paxillar area, and the latter con- 
tracts continuously up to the extremity ; the area is also at a slightly lower level than the 
marginal plates, and this, together with the well-rounded curvature of the latter, gives an 
emphatic character to the border. Except on the inner part of the ray the breadth is 
greater than the height, and is considerably greater than the length throughout. The 
abactinal and lateral planes of the plate are united by a full and well-rounded semicircular 
curve. ‘The two or three plates in the midst of the interbrachial are are shorter and less 
tumid in their curvature than the succeeding plates. ‘The surface of the plates is covered 
with rather large distinctly spaced granules, which become smaller, more crowded, and 
Ri 
