REPORT ON THE ASTEROIDEA. 289 
upon one another. The paxill along the sides of the rays are arranged in regular obliquely 
transverse lines, seven or eight being present in each series near the base of the ray. The 
paxille 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 paxille. The divisions between succeeding plates are well marked. 
Usually two of the obliquely transverse series of paxillee 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. here 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 L1.—1888.) 37 
