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 example 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 line. 
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. 
