218 THE VOYAGE OF H.M.S. CHALLENGER. 
15. Astropecten cingulatus, Sladen (Pl. XXXV. figs. 5 and 6; Pl. XX XIX. figs. 1-3). 
Astropecten cingulatus, Sladen, 1883, Journ. Linn. Soc, Lond. (Zool.), vol. xvii. p. 266. 
Rays five. R=28mm.;r=9mm. R>3r._ Breadth of a ray at the base, 10 mm. 
Rays rather short and of moderate breadth, tapering gently with a slight curve to the 
extremity, which is sharply pointed. Interbrachial arcs subacute and not rounded. 
The paxillar area is very limited in consequence of the great breadth of the supero- 
marginal plates. The paxille are large upon the disk, but become smaller along the rays ; 
the former have four or five rather large granules in the centre on the tabulum, surrounded 
by a dozen or more small short spinelets. Along the rays there are not more than two or 
three central granules, and these are arranged in line, the paxilla (tabulum) being more or 
less elongately oval in the direction of the axis of the ray. The paxille are closely placed. 
In the centre of the disk a small conical elevation is present, upon and in the neighbour- 
hood of which the paxillee are smaller. 
The supero-marginal plates, which are nineteen in number from the median interradial 
line to the extremity, are all much broader than high, the breadth of those midway on 
the ray being greater than the adjacent paxillar area. The breadth of the supero-marginal 
plates increases towards the summit of the interbrachial arc, where the maximum is 
attained; the innermost plate of each ray, which is contiguous to the median interradial 
line, is triangular or wedge-formed, the apex being directed outward; whilst the bases 
of the two adjacent triangles form a wide rounding to the inner contour-line of the 
marginal wall. The border formed on the abactinal surface by the marginal plates is 
very broad and conspicuous. The length of the supero-marginal plates in the inner half 
of the ray is not more than one-third of their breadth. The plates are rather tumid 
along the median line of breadth, which produces a slight furrow between each ; and the 
surface of the plate is covered with closely placed uniform granules, which become finer 
along the margins. No spinelets, tubercles, or enlarged granules are present on the plates. 
The infero-marginal plates are broader than high, and extend very slightly beyond the 
superior series. Each bears two lateral spines, standing side by side, which are equal in 
length, short, very delicate, cylindrical, or faintly flattened, tapering to a sharply pointed 
extremity, and slightly bent. Behind these stand two or three very small, delicate spine- 
lets; and a row of similar, though somewhat smaller, spinelets is placed on the adoral 
side of the plate. The surface of the plate is covered with small, flat, subcircular squamules, 
rather widely spaced, the margins being bordered with crowded, short, delicate, ciliary 
spinelets, hidden in the divisional furrows. 
Only two or three actinal intermediate plates are present in the immediate interradial 
area: these carry usually one moderately long tapering spinelet, surrounded by a 
marginal series of papilliform spinelets. 
‘The armature of the adambulacral plates usually forms three series, although the third 
