REPORT ON THE ASTEROIDEA. 425 
subequal on the outer part. This series forms the margin of the ray, and is probably the 
supero-marginal series of plates. The plates of the next series (the infero-marginal), which 
also extend to the extremity, are rather smaller, and all are longer than broad. Between 
these and the adambulacral plates are two series of actinal intermediate plates all much 
longer than broad. The abactinal and the two series of marginal plates were covered with 
a very thin skin, and do not appear to have borne any spines, excepting the innermost two 
or three plates of the infero-marginal series, whose armature resembles that of the adjacent 
intermediate plates. The actinal intermediate plates bear short, equal, broad, compressed, 
lanceolate, pointed spinelets, all in thin membranous sacs, appressed to the ray and 
arranged in a line upon the plate, forming longitudinal series along the ray. 
The adambulacral plates are broader than long, definitely spaced, with a prominent 
angle towards the furrow, and a slight convexity or keel along the median transverse line 
of the actinal surface at right angles to the furrow. All the plates are equally prominent 
into the furrow. Their armature consists of a transverse lineal series of five short spinelets 
equidistantly placed on the keel, the innermost or furrow spine being the smallest, tapering 
and pointed, the other four subequal or diminishing in size as they recede from the furrow, 
much broader, compressed, and more or less sublanceolate in form, radiating slightly apart, 
and usually appressed to the ray, the direction being aboral and slightly outward. 
The mouth-plates trend upward into the buccal cavity. The actinostome is large and 
its margin declivous. 
The madreporiform body, which is small, circular, and convex, is situated external to the 
adjacent primary basal plate. Its surface is grooved with very few, coarse, convoluted striz. 
The anal aperture is distinct and excentric, situated between the dorso-central and the 
right postero-lateral basal plate, the margin of the latter being lunated for its reception. 
The ambulacral furrow is wide. The tube-feet, which are arranged in two simple 
and regular rows, have fleshy terminal knobs or disks. 
The terminal plate, which is large and elongate, is deeply indented posteriorly on the 
abactinal surface for the insertion of the last three or four median radial plates. It bears 
at the extremity two pairs of comparatively large, conical, pointed spinelets, and several 
smaller ones. 
Colour in alcohol, bleached white on the abactinal surface, where the membrane has 
been abraded from the plates. Traces, however, of the membrane, which are of a dark 
purplish brown, are present at the angles and in the sutures between the plates; and in 
the present condition of the specimen preserved in spirit give a remarkably ornate char- 
acter to this species. The actinal surface is light brown. The colour of the ambulacral 
tube-feet is very dark brown, the terminal knob, which is much lighter, being almost white. 
Locality.—Station 191. In the Arafura Sea, north-west of the Arrou Islands. Sep- 
tember 23, 1874. Lat. 5° 41’ 0” S,, long. 134° 4’ 30” E. Depth 800 fathoms. Green 
mud. Bottom temperature 39°'5 Fahr. ; surface temperature 82°°2 Fahr. 
(ZOOL, CHALL. EXP.—PART LI.—18838.) 54 
