406 THE VOYAGE OF H.M.S. CHALLENGER. 
in outline and form eight regular longitudinal series, the abactinal series on each side being 
much smaller than the others, gradually diminishing as they proceed along the ray and 
dying out altogether between the outer fourth and fifth of the ray. They are covered with 
small papilliform, almost spiniform or scutiform, granules, which are so arranged round the 
papular orifices that they trend over the apertures and appear to protect them almost in 
a valve-like manner. This produces the appearance of the area being occupied by a 
number of rosette-like bodies not very unlike the valvate pedicellariz found in some 
forms of Archasteride. The papulze are numerous, varying in number from ten to 
twenty. 
The actinal intermediate plates are covered with large, rather irregular, rounded 
granules, which are larger than those on the marginal plates. At least three series of 
plates may be counted between the marginal and adambulacral plates at the base of the 
ray, a slight convexity of the plate and a depression at the angles assisting in the discern- 
ment of the plates. : 
The armature of the adambulacral plates is disposed in two series, in conformity with 
the usual arrangement in Ophidiaster. Of the inner or furrow series there are two 
spinelets to each plate, one much larger than the other, and these form a continuous 
uniserial series along the furrow, large and small spinelets alternating. The larger spinelet 
is very short, broad, expanding towards the tip, and obtusely rounded. It has the appear- 
ance at first sight of being compressed laterally, but when examined carefully with a 
magnifying-glass a median keel is seen on the outer surface which gives the papilla a 
subprismatic form, more or less subtriangular in section. The small alternating spinelets 
are much smaller, and little more than scutiform granules. The outer series of spinelets are 
placed close behind the furrow series, one standing opposite each of the small spinelets of 
the furrow series. They are small for the genus in comparison to the size of the starfish, 
but are robust, fusiform, compressed and almond-shaped ; becoming on the outer part of 
the ray more conical and wider apart, appearing only to occur there on alternate plates. 
The interspaces between the spinelets of this series are occupied by small papilliform 
granules rather smaller than those on the actinal intermediate plates generally. Small 
entrenched pedicellarize are occasionally present on the actinal intermediate plates im- 
mediately external to the outer spinelet of the adambulacral plates, and also, but apparently 
more rarely, on the other intermediate plates. A number of the pedicellarice adjacent to 
the adambulacral spines are remarkable for the very large bosses present on each side of 
the constricted part of the figure-of-eight, much larger than any of the adjacent granules. 
The similarly-placed bosses on the pedicellarize in the abactinal area are very small. 
The madreporiform body is large and circular, and marked with very fine striations. 
It is situated external to a primary basal plate, and its lower margin masks the union 
of the two innermost plates of the lateral series of abactinal plates next the median 
radial series of the two adjacent rays. The granules on the plates which touch the lower 
