REPORT ON THE ASTEROID KA. 9 



The mouth-plates are large, prominent, and convex actiually, presenting a broad and 

 rounded, but centrally rather flattened, margin towards the actinostome ; and the median 

 suture of the pair is imperfectly closed. Their armature consists of a marginal series of 

 five mouth-spines on each plate, the innermost one being twice or three times as long and 

 robust as the others, which are subequal and rather widely spaced. On the actinal surface 

 of each plate are three (or sometimes only two) robust tapering spinelets, standing wide 

 apart and forming a Une parallel to the median suture ; these do not appear to attain 

 the size of the superficial actinal spinelets on the adambulacral plates. The surface of 

 the plates is covered with membrane, and no other spinelets are present. 



The actinal interradial areas are of very small extent, and do not reach beyond the 

 fifth adambulacral plate. The size and number of the intermediate or ventral plates is 

 undeterminable in spirit specimens on account of the membrane with which they are 

 overlaid. So far as can be judged, they appear to be comparatively large, and are 

 certainly few in number. A few of these bear one, or occasionally two, small spinelets 

 1*5-2 mm. in length. 



The anal aperture is subcentral but indistinct, surrounded by large spinelets. 



The madreporiform body, which is large and oval, is situated midway between the 

 centre of the disk and the odd interradial supero-marginal plate. Its surface is slightly 

 convex, finely grooved with numerous highly convoluted striation furrows, and has on 

 that account a remarkable resemblance to the " brain " coral. Several large spinelets 

 surround its margin, the largest being at its adcentral end. 



The papulae are very small and numerous, but confined to an area at the base of the 

 rays, which does not extend beyond the fourth supero-marginal plate. The area occupies 

 nearly the whole breadth between the supero-marginal plates, and extends well upon 

 the disk, but no papulse are present along a broad band which traverses the median 

 interradial line. 



No pedicellariae of any kind are found upon this species. 



Colour in alcohol, a dirty bleached ashy grey. 



Individual Variation. — There is a fragmentary specimen from Station 235, in a very 

 bad condition, of a much smaller example than the type above described, in which the 

 spines of the actinal surface generally are proportionately much more delicate. From 

 their length and character, I am disposed to consider this a feature of individual or even 

 locational variation, rather than a phase of growth ; a remark, however, which is merely 

 conjectural, for its validity could only be proved by the examination of a large series of 

 specimens. 



Localities. — Station 237. Off the coast of Japan, south of Kawatsu. June 17, 1875. 

 Lat. 34° 37' 0" N., long. 140° 32' 0" E. Depth 1875 fathoms. Blue mud. Bottom 

 temperature 35°*3 Fahr. ; surface temperature 73°'0 Fahr. 



(ZOOL. CHALL. EXP. — PART LI. 1887.) 2 



