506 THE VOYAGE OF H.M.S. CHALLENGER. 
radiate from the tips of the spinelets and pass to those standing in close proximity around, 
the bands crossing at various angles, overlying and underlying one another, and forming 
an interlacing tissue rather than a truly reticulated structure. The spiracula, which are 
moderately large, are irregularly placed and not numerous. The paxillee seldom have 
more than three spinelets, which are usually aggregated close together and especially so 
along the median line of the ray and at the extremity, forming a crown of small expansion. 
Towards the disk the spinelets are more widely spaced; and the paxille, which form the 
pseudo-sides of the ray, are disposed in a perfectly straight line, no stragglers encroaching 
on the web or interradial area. 
The oscular aperture is large aud conspicuous; the valves are regular and formed of 
comparatively few spinelets, seldom more than a dozen in each. The outer margin of the 
oscular ring is very strikingly marked out by short, prominently protruding, pointed 
spinelets, excentrically directed, very regularly disposed, and from the tips of which the 
membrane hangs in graceful folds. 
The ambulacral furrows are moderately broad, sublanceolate in outline, fairly uniform 
in width except near the mouth where they are constricted, and along the outer fifth 
where they taper rapidly up to the extremity. The armature of the adambulacral plates 
consists of two short, acicular, pointed spinelets, covered with membrane which forms a 
moderately developed terminal sacculus. In some specimens this appears to be much 
more developed in the adoral spine of the pair than in the aboral, which seems frequently 
to be smaller than the other. The aboral spine is also placed higher in the furrow than 
the adoral. The aperture-papille are large, and with their investment, broadly lanceolate 
or acumino-spatulate in form. 
The mouth-plates are short and rather broad, the aboral prominence being blunt and 
well rounded. Hach plate bears two very short, robust, stumpy secondary or superficial 
spines, the adoral one (which is placed forward on the plate) being shorter even than the 
mouth-spines proper, but much more robust. The mouth-spines proper, which are four 
or five in number on each plate, are rather long, fine, and nearly equal in length. 
The actino-lateral spines are robust and well-spaced, the fourteenth or fifteenth from 
the mouth being longest. None meet in the interradial median line, not even the longest, 
the space being filled in with fleshy membrane. 
Colour in alcohol, dirty white in large specimens, greenish grey in those of smaller 
§1Ze. 
Locality.—Station 235. Off Japan, south of Omae saki. June 4, 1875. Lat. 
34° 7’ 0" N., long. 138° 0’ 0” E. Depth 565 fathoms. Green mud. Bottom temperature 
38°:1 Fahr.; surface temperature 73°°0 Fahr. 
Remarks.—Hymenaster glauwcus may be readily distinguished by the conspicuously 
defined radial areas raised in relief above the rest of the abactinal surface, by the paxill 
with three spinelets, and by the character of the supradorsal membrane. 
