ASTEEOIDEA OF H.M.S. ' CHALLENGEE ' EXPEDITIOIf. 227 



Mouth-plates large and prominent, the mouth-angle presenting 

 a broad well-rounded keel. At the aboral extremity there is a 

 graceful slope ; the margins of the plates are united, and do not 

 expose the odontophore. In the median line of the keel, how- 

 ever, midway between the extremities, a hollow elliptical space 

 occurs where the margins of the plates do not meet. The adoral 

 extremity is somewhat rounded, and a single short conical spine- 

 let is borne at the union of the two plates, occasionally with a 

 small secondary companion standing above it. No other mouth- 

 spines are present on the plates. On the side of each mouth- 

 plate two of the segmental pits and their papillae are present : 

 the aboral one is the larger of the two, and is placed rather 

 nearer the aboral extremity than midway on the plate, the 

 smaller pit and papilla being about equidistant between the adoral 

 extremity of the mouth-plate and its larger companion. Actinal 

 interradial areas very small and subtriangular, covered with a 

 leathery skin through which the plating is scarcely discernible. 



Colour, in alcohol, yellowish grey, with a brownish shade near 

 the disk, darkest near the borders of the area adjoiuing the 

 marginal plates. 



Station 286. Lat. B3° 29 'S., long. 133° 22' W. Depth 2335 

 fms. ; bottom temperature 0°"8 C. ; red c\a,j. 



POECELLANASTEE (lEACILIS, U. Sp. 



Rays five, rather long and slender, slightly tapering, somewhat 

 flattened. Tnterbrachial angles wide, the immediate arm-angle 

 being more or less straight. Minor radial proportion 45 per 

 cent.; i2=10 millim., r=4'5 millim. Disk modei^ately high 

 and inflated. Dorsal area covered with a thin membrane. 

 Spinelets, borne on spicule-like plates, confined to bands along 

 the interradial lines, and a few surrounding the epiproctal tube, 

 the radial area being entirely without spinelets. The spinelets 

 are very minute, little more than microscopic spicules, elongate, 

 cylindrical, not tapering, covered with a thin membrane through 

 which the calcareous base and shaft are distinctly visible. The 

 tubular epiproctal prolongation is moderately well developed, 

 broad at the base and tapers rather rapidly. 



Marginal plates not high, forming an almost perpendicular wall 

 which bends inward very slightly ; they do not arch over on the 

 sides of the rays and their curvature produces only a slight 

 rounding of the margin. The dorsal area of the ray is flat, and 



