414 THE VOYAGE OF H.M.S. CHALLENGER. 
species are a few entrenched pedicellariz, isolated, and at wide intervals apart. I am not 
aware that the presence of these organs has been noticed previously in this form. 
2. Nareissia trigonaria, n. sp. (Pl. LXV. figs. 5-8). 
Rays five. R= 62mm.;7=13mm. R= 4757. Breadth of a ray between the 
third and fourth infero-marginal plates, 12°5 mm. 
Rays elongate, but much shorter than in Narcissia canariensis, rather broad, distinctly 
triangular in section, with a strongly-marked median keel, in which there is a con- 
spicuous break at the base of the ray, separating the keel of the ray from the elevated 
part of the disk. The sides of the keel slope regularly to the margin. The actinal area 
is plane, rounded at the margin. ‘The interbrachial arcs are subacute. 
The abactinal plates are large along the keel on the inner half of the ray, somewhat 
irregular, and with a tendency to become tubercular. All the plates are covered with a 
minute, uniform granulation. The papule are single and isolated. 
The marginal plates are well-defined and slightly convex. There are about thirty- 
seven infero-marginal plates between the median interradial line and the extremity. 
Papulz are present, either singly or in pairs, between the infero-marginal and supero- 
marginal plates along the inner half of the ray, but do not occur on the outer half. Well- 
defined narrow channels are present between neighbouring plates. 
The armature of the adambulacral plates is disposed in three series, each normally with 
four short papilliform spinelets. The spinelets of the inner or furrow series, which are the 
longest, are subequal, slightly flattened, broader at the tip than at the base, and obtusely 
rounded : they form a slightly radiating comb on the furrow margin. The second series, 
which is likewise composed of four or occasionally five spinelets, forms an obliquely 
disposed line, the adoral extremity being more remote from the furrow. Three of the 
spinelets are broader and more robust than the furrow series, are broad, flaring, and obtuse 
at the tip, with a tendency to assume more or less of a subprismatic shape ; the adoral 
spine is much smaller than the others, and might often be counted with the outer series. 
The outer series are small, irregular, subprismatic papillee, which may be pointed or chisel 
edges at the tip; they are little more than granules, and very slightly larger than the 
granules on the adjacent intermediate plates. 
One longitudinal series of actinal intermediate plates extends nearly to the extremity 
of the ray. The actinal interradial regions of the disk are small, and, although there are 
four intermediate plates on each side of the median interradial line, the series they repre- 
sent do not extend beyond the base of the rays, the fifth infero-marginal plate being con- 
tingent on the first series of intermediate plates above-mentioned. The plates of the first 
series of intermediate plates are well defined by intervening channels. The granules on 
the intermediate plates are rather larger than those on the marginal plates and are 
distinctly spaced. There do not appear to be any papule on the actinal surface. 
