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 

 thomlets 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 pedicellarise are also present. There is no trace of any cal- 

 careous ridges or transverse sacculi with crowded pedicellarife 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 175 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 1"5 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 

 decree. 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 

 pedicellarise. 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 25 

 mm. in length. It is covered with a delicate membranous sheath, on which are borne a 

 considerable number of pedicellarise, 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 pedicellarise 

 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 



