ASTEEOIDEA OF H.M.S. ' CHALLENGER ' EXPEDITIOlf. 265 



by the presence in the innermost portion of the ray of a minute 

 granule or rudimentary spinelet in a corresponding position on 

 the adoral side of the plate. This arrangement causes the broader 

 middle spinelet at first sight to appear as the aboral of two spines 

 which form a true outer series, directed outward towards the 

 margin of the ray. 



Mouth-plates elongate and narrow, with a single row of 8-10 

 papilliform spinelets on their surface, which are very small out- 

 wardly, but increase in length as they approach the mouth, the 

 innermost spine being longer than any of the others and directed 

 horizontally. The two series of spinelets on the companion plates 

 of a mouth-angle are generally apposed to one another. On the 

 free margin of the mouth-plate there is a lineal series of short, 

 rather robust spinelets directed horizontally, which increase in 

 length as they approach the inner extremity of the plate, the 

 innermost spinelet being very little shorter than the innermost 

 spinelet of the superior series just mentioned, and, standing at 

 the same level, forms together with it the horizontal fan of mouth- 

 spines which proceed from each mouth-angle and cover the mouth. 

 The adambulacral plate adjoining the mouth-plates is much 

 broader and shorter than the others, and bears a lineal series of 

 8 or 9 short papilliform spinelets on either side, the two series 

 being apposable. 



The paxillar area is wide, measuring more than three times 

 the width of the supero-marginal plates near the middle of a ray, 

 and is very regular in composition. The paxillae are large and 

 well spaced, and have one large granule -like spinelet in the centre 

 of the tabulum, and 7 to 10 very short clavate spinelets on the 

 circumference radiating out widely, almost horizontally. Occa- 

 sionally on the disk, paxillse have 2-4 central granules ; but the 

 single, large-sized, low granule is very characteristic. On the 

 sides of the rays the paxillse are arranged in transverse lines 

 about 3 or 4 in each ; the median dorsal band scarcely defined. 

 In the centre of the disk an anal peak is present, in the neigh- 

 bourhood of which the paxillse become very small and crowded. 

 In some cases the centre of the cone is invaginated. 



Madreporiform body entirely hidden by paxilla3. 



Colour, in alcohol, ashy grey. 



Station 203. Lat. 11° 7' N., long. 123° 7' E. Depth 12 to 

 20 fms. ; mud. 



