114 THE VOYAGE OF H.M.S. CHALLENGER 



extremity, and shorter than those of the furrow series. In the middle of this outer series, 

 or immediately external to it, is a larger spinelet equal in length to the furrow series, 

 but much more robust, conical, and sharply pointed, usually directed outward and 

 obliquely forward ; and behind this, two more series of small granuliform spinelets which 

 form a transition to the spinulation of the infero-marginal and actinal intermediate 

 plates. It should be stated that it is not always possible to define the arrangement with 

 as much regularity as here described, at least in the last three longitudinal series, and 

 the armature in consequence often assumes a more or less grouped appearance. The 

 furrow series, the first external longitudinal series, and the prominent conical spine 

 behind always maintain, however, their regularity. 



The actinal interradial areas are well-developed, and the intermediate plates are 

 covered with a uniform, papilliform spinulation, which has a tendency to appear squami- 

 form and similar to the covering of the infero-marginal plates. Here and there short, 

 flattened, adpressed, pointed spinelets occur, suggesting the presence of one in the centre 

 of each of the larger plates on the inner part of the area ; but the uniformity of the 

 general spinulation prevents any trace of the individual plates being made out. 



The mouth-plates are elongate, and their armature is arranged with great regularity. 

 Each plate bears two lineal series of about ten to twelve papilliform spinelets, which 

 increase in length as they approach the mouth. On the outer part of the plate the com- 

 panion series on each plate are close together and nearly parallel, but on the inner part 

 of the plate the inner six spinelets are a little more widely spaced from the companion 

 series. There are thus four regular series of spinelets on each pair of mouth-plates, and the 

 innermost spine of each series is slightly larger and more robust than any of the others. 

 The inner six pairs of spinelets differ but little in length, and are considerably longer 

 than the outer spinelets, which are all on the surface of the plate. 



Colour in alcohol, a dirty bluish grey over the paxillar area, an ashy yellowish grey 

 on the margins and actinal surface. 



Locality. — Simon's Bay, Cape of Good Hope. (Exact position and depth not 

 recorded.) 



Remarks. — In the exanqjle above described the abactinal area is almost flat, excepting 

 the faintest approach to convexity in the radial areas of the disk, and a corresponding 

 slight sulcus or depression along the median interradial Hue. 



In a younger specimen, having a major radius of 32 mm., the abactinal area of the 

 disk is distinctly convex and inflated, a character which is further emphasised by the faint 

 interradial depression ; and the convexity extends along the abactinal area of the rays. 

 It is also to be remarked that in the younger example, the prominent conical spine in the 

 adambulacral armature is not yet conspicuously developed. 



