REPORT ON THE ASTEROIDEA. 289 



upon one another. The paxilhe along the sides of the rays arc arranged in regular obliquely- 

 transverse lines, seven or eight being present in each series near the base of the ray. The 

 paxillce in the central area of the disk and in the narrow median strip along the rays 

 are not included in this arrangement. A certain longitudinal disposition, though scarcely 

 to be described as subregular, occurs along the ray. 



The supero-marginal plates are small and subrhomboidal in form, the sutures between 

 adjacent plates forming obliquely transverse lines, which trend from within outward and 

 slightly backward. The supero-marginal plates are thirty in number counting from the 

 median interradial line to the extremity. There is a small odd triangular plate in the 

 median interradial line which does not reach the margin. The innermost marginal plates 

 have the breadth slightly in excess of the length, but along the greater part of the ray the 

 length is slightly greater than the breadth. At the extremity the breadth of the plates is 

 greater than the length and owing to their posture on the ray the height is the predomi- 

 nant dimension. On the inner part and until quite near the extremity the plates are low 

 and flat-lying, with the height less than the other dimensions. The surface of the plates 

 is covered with numerous comparatively large, coarse, low, subprismatic, truncate granules 

 all of uniform size, not specially crowded and superficially similar in all respects to the 

 granules on the paxillse. The divisions between succeeding plates are well marked. 

 Usually two of the obliquely transverse series of paxillse are opposite each supero-mar- 

 ginal plate. 



The infero-marginal plates correspond in length to the superior series, and are confined 

 almost entirely to the lateral wall, curving very slightly towards the actinal surface, very 

 little of their surface being seen when the starfish is viewed from below ; though the 

 amount presented may vary slightly according to the inflation of the ray and the consequent 

 posture of the marginal plates. When the lateral wall of the ray is placed in the direct 

 line of view, the height of the plate is seen to be rather greater than the length on the 

 inner part of the ray and at the extremity, but rather less than the length midway along 

 the ray. They are covered with precisely similar granules to those on the supero-marginal 

 plates. There is also an odd infero-marginal plate in the median interradial line, narrow 

 and wedge-shaped, its outline being an isosceles triangle, whilst that of the odd supero- 

 marginal plate is an equilateral one. 



The adambulacral plates are short and broad, and their armature consists on the inner 

 half of the ray of four or five oblique pairs of spines standing one behind the other ; but 

 on the other part no more than three pairs are present. The spines of the pair which 

 stands on the furrow margin are slightly larger than the rest, cylindrical, robust at the 

 base, tapering, and more or less pointed. In the succeeding pairs the spines are less 

 tapering and less pointed, and the outer pairs are considerably smaller than the others ; 

 on the outer half of the ray being scarcely distinguishable from the granules on the adjacent 

 intermediate plates. The pair next the furrow pair are often so very oblique in their 



(ZOOL CHALL. EXP. — PART LI. — 1888.) 37 



