218 T1IE VOYAGE OF H.M.S. CHALLENGER. 



15. Astropecten eingulatus, Sladen (PL XXXV. figs. 5 and 6 ; PI. XXXIX. figs. 1-3). 

 Astropecten eingulatus, Sladeii, 1883, Journ. Linn. Soc. Lond. (Zool), vol. xvii. p. 266. 



Rays five. R = 28 mm. ; r = 9 mm. R > 3 r. 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 paxillse 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 paxillse are closely placed. 

 In the centre of the disk a small conical elevation is present, upon and in the neighbour- 

 hood of which the paxillse 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 



