266 MR. W. PERCY SLADEN ON THE 



ASTROPECTEN CINGULATUS, n. Sp. 



Eays five. JS>3r ; JR=28 millim., r=9 millim. Eays rather 

 short and of moderate breadth, tapering gently witli a sliglit curve 

 to the extremity, which is not sharply pointed. Breadth of a 

 ray at the base 10 millim. Interbrachial angles subacute and 

 not rounded. 



Supero-marginal plates 19 in number from the interbrachial 

 line to the tip, 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 

 arm-angle, where the maximum is attained ; the innermost plate 

 of each ray, which is contiguous to the median interbrachial line, 

 is triangular or wedge-form, the apex being directed outward ; 

 whilst the bases of the" two ad-jacent triangles form a wide 

 rounding to the inner contour-line of the marginal wall. The 

 border formed on the dorsal 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 slightly tumid along the median line of breadth, which pro- 

 duces a slight furrow between each i 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. 



Infero-marginal plates broader than high, and e.xtend very 

 slightly beyond the superior series. Marginal spines two, stand- 

 ing side by side, equal in length, short, very dehcate, cylindrical 

 or faintly flattened, tapering to a sharply-pointed extremity and 

 slightly bent. Behind these stand 2 or 3 very small delicate 

 spinelets ; and a row of 4 or 5 similar, though somewhat smaller, 

 spinelets are placed on the aboral 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 ventral plates are present in the immediate 

 interbrachial area; these carry usually one moderately long 

 tapering spiuelet surrounded by a marginal series of papilliform 

 spinelets. 



Ambulacral spines usually forming three series, although the 

 third or outer series is often absent or indistinguishable from the 

 ciliary spinelets of the ventro-marginal plates on the outer part of 



