REPORT ON THE ASTEROIDEA. 119 



covered with short, small, conical-tapering, and sharply pointed thornlets, which are rather 

 widely spaced, adpressed, and diminished in size near the margins, the smaller ones 

 being less sharply pointed. At the extreme margin of the plate adjacent to the supero- 

 marginal series there are a few of the rounded grannies similar to those on the latter, 

 which gradually form a transition to the thornlets above described. At the lateral 

 margins of the plates the thornlets stand in a lineal series which is directed obliquely 

 towards the adjacent plate and forms a sub-fasciolar fringe arching over the slight channel 

 at the suture. On the inner part of the channel six or seven of the thornlets on each 

 of the adjacent plates are modified into short flattened truncate papillae, those of one 

 plate being directly opposed to the corresponding series on the adjoining plate, and 

 thus form a peculiar and more definitely fasciole-like organ. On the three innermost 

 sutures in the interbrachial arc this structure is not present, but it may be traced along 

 the ray as a definite organ almost to the tip, diminishing of course in size as it proceeds 

 outwards. 



The armature of the adambulacral plates consists of a furrow series of eight or nine 

 short, slightly compressed, obtusely rounded papilliform spinelets, equal in length, and 

 with the flattening at right angles to the direction of the ray. The spines appear slightly 

 geniculated and stand upright side by side, and their base line is a flattened curve, 

 the curvature inwards being greatest at the aboral extremity of the series. The two 

 last spinelets at this end of the series stand slightly apart from the rest and from one 

 another, are somewhat smaller and different in character, and the outermost spinelet at 

 the adoral extremity of the series is also a little smaller than those which actually form 

 the general ranks of the series. The comb of furrow-spinelets, even when standing 

 perpendicularly, touches that of the corresponding plate on the opposite side of the furrow, 

 and consequent on the curvature of the line of furrow spines on each adambulacral plate 

 a series of small circular apertures is formed in the median line of the furrow through 

 which the ambulacral tube-feet may be seen, and indeed were it not for these aper- 

 tures the ambulacral furrow would be entirely enclosed. External to the furrow series 

 is an irregular lineal series of four or five short, conical-tapering, pointed spinelets, 

 running parallel to the furrow; these are rather wide apart and shorter than the 

 furrow series on the inner part of the ray, where they are little more than blunted 

 papillae, but increase slightly in length as they proceed outwards, and one or two of the 

 middle ones may be twice the length of the others. On the plates near the mouth 

 there are seldom any other granules external to the lineal series ; near the commence- 

 ment of the free part of the ray, however, a few very small thornlike granules are 

 present, whilst near the middle of the ray these may form a second irregular lineal series 

 external and parallel to the outer series of spinelets above-mentioned. 



The actinal interradial areas are comparatively small. The series of plates adjacent 

 to the adambulacral plates have a regular marginal arrangement of papilla? simulating 



