REPORT ON THE ASTEROIDEA, 609 
Rays very long and attenuate, but of a comparatively robust habit in proportion to the 
small size of the disk, when compared with other species of the genus, narrow and cylindrical 
at the base, but gradually swelling into an elongate fusiform ovarial inflation, which 
contracts gradually and terminates at 45 to 48 mm. from the disk, thus occupying about 
the proximal fifth of the length. Beyond the ovarial inflation the ray is subtriangular, 
with a broad median carination, and tapers gradually to the extremity. 
The disk is small and subdepressed, with the abactinal surface subplane and on the 
same level as the base of the rays or even slightly lower. The abactinal surface is covered 
with an exceedingly delicate semitransparent membrane, beset with very minute micro- 
scopic spinelets, each borne on a small subcircular spicule-like plate buried in the membrane 
and widely spaced. No definite order of arrangement is distinguishable amongst these 
spiniferous spicules, and the delicacy of the abactinal membrane is so great that traces 
of the internal organs may be seen through the interspaces. The membrane which covers 
the abactinal surface of the rays is even more delicate than that of the disk. The inner 
portion of the ray, as far as the ovarial region extends, is furnished with transverse 
aunular ridges, similar to those in Brisinga endecacnemos. These are very narrow, often 
irregular, and more or less flexuous, and their normal position appears to be opposite 
alternate adambulacral plates, but this is not invariable. A few isolated spicules may 
be found in the intermediate spaces, and saccular bands crowded with small pedicellariz 
are present, but from the condition in which the specimen now is, I am unable to remark 
on their character or dimensions, but where preserved they appear to be broad continuous 
bands extending from margin to margin. The transverse keels or ridges are formed of a 
number of small ossicles imbricating on one another and bearing minute, isolated, short, 
thorn-like spinelets. Beyond the ovarial region the abactinal membrane was of great 
delicacy, and where present may be seen to form transverse folds or plications, but owing 
to its delicacy it is wanting on the greater portion of the ray. 
The ambulacral furrow is wide and measures 2°75 mm. at a part where the ray is 
4°5 mm. (about 70 mm. from the disk). The adambulacral plates are longer than broad, 
measuring 2 mm. at 70 mm. from the disk, and the furrow-margin of the plate is deeply 
concave. The adambulacral armature consists of :—(1.) two small inner spinelets, directed 
horizontally over the furrow ; (2.) a longer and more robust spine standing perpendicularly 
on the actinal surface of the plate; and (3.) a still longer lateral spine, usually borne on 
every third plate, z.e., with two unarmed plates between, but sometimes there is only 
one. The two small inner spines are attached, one near the adoral and the other near 
the aboral end of the furrow-margin of the plate, and are directed horizontally over the 
furrow at aright angle to the margin. It thus follows that there are two small spinelets 
between each consecutive ambulacral tube-foot. These spines are of equal size, less than 
1 mm. in length, cylindrical, and covered with extremely delicate membrane, on which 
are borne a few comparatively large pedicellariz. The actinal spine is articulated on a 
(ZOOL. CHALL. EXP.—PART LI.—1888.) 77 
