622 THE VOYAGE OF H.M.S. CHALLENGER. 
is extremely delicate, and I do not detect in the fragments preserved any trace of an 
ovarial inflation. All the fragments appear to give a part, if not the whole, of the basal 
portion. This membrane is smooth and stretched, and a few widely spaced microscopic 
thornlets are present, grouped in more or less definite, rather broad, transverse bands. 
Examination under the microscope with suitable illumination reveals the presence of under- 
lying plates upon which the thornlets are borne, and I have on these grounds ranked the form 
as a Freyella. A few small pedicellariz are also present. There is no trace of any cal- 
careous ridges or transverse sacculi with crowded pedicellariz as in Brisinga. Beyond the 
basal part of the ray the abactinal membrane is extremely delicate and perfectly transparent. 
The ambulacral furrow is wide, and measures about 1 mm. at a part where the ray 
measures 1°75 mm., at 11 mm. from what I believe to be the base of the ray. The adam- 
bulacral plates are much longer than broad, and the ninth measures nearly 15 mm. at 12 
mm. from the base. ‘The shape of the plate seen actinally greatly resembles that of a long 
caudal vertebra, its furrow margin being deeply concave, and the outer margin to a less 
degree. The breadth of the plate at the adoral extremity is rather greater than at the 
aboral extremity. The adambulacral armature consists of :—(1.) A minute, delicate, inner 
spine, directed over the furrow, about 0°5 mm. in length, placed at the aboral extremity 
of the plate, directed horizontally and at a slight angle adorally. This spinelet is covered 
with very thin membrane, on which are borne near the tip two or three or more small 
pedicellarize. On the inner part of the ray a second spinelet is placed at the adoral end of 
the plate, but not more than half the size of that above described; it is also directed hori- 
zontally, but at a slight angle aborally. This small adoral spinelet does not appear to 
extend further than the eighth plate. (2.) On the actinal surface of the plate is an exceed- 
ingly delicate, tapering, needle-like actinal spine, the ninth from the base measuring 2:5 
mm. in length. It is covered with a delicate membranous sheath, on which are borne a 
considerable number of pedicellariz, and is articulated on a small tubercular eminence 
rather nearer the aboral end than midway on the plate. (3.) A single elongate, extremely 
delicate lateral spine is articulated on a small plate—a rudimentary infero-marginal plate— 
so intimately united to the adambulacral plate as to appear like a tubercular eminence on 
its surface. One appears to be present on each alternate plate. The twenty-second or 
twenty-third spine (which appears to be the longest on the fragments preserved) is about 
5 mm. in length, and is invested with a thin membranous sheath, having a small saccular 
extension at the distal extremity, and bearing a great number of minute pedicellariz 
usually on peduncles. The ambulacral ossicles or segments are remarkable for their length, 
and when seen from above have the appearance of two thin cylindrical rods placed side 
by side. 
The actinostome is wide, and measures 7°5 mm. in diameter in a disk 11°5 mm. in 
diameter. The mouth-plates are small and rather elongate, slightly expanded and rounded 
anteriorly, and the median suture-line is not closed. Their armature consists of three 
