96 THE VOYAGE OF H.M.S. CHALLENGES. 



series of six or seven delicate, tapering, sharply-pointed spinelets, arranged on the margin 

 of the plate, and radiating apart horizontally over the furrow ; the two or three median 

 spinelets being the longest, and the outermost on each side less than one-third their 

 length. (2.) On the surface of the plate is a lineal series of three or four small spinelets, 

 running parallel to the median line of the ray and close behind the furrow series ; one 

 of these is comparatively elongate, tapering, and robust, whilst the others are mere papilli- 

 form granules, irregularly spaced. On the outer margin of the plate a lineal series of 

 miliary thornlets may be present. 



The mouth-plates are very elongate and narrow, the united pair being slightly convex. 

 The median suture is imperfectly closed ; the inner margin at the outer extremity of 

 each plate is rounded, and a spiniferous plate is visible in the space thus formed. The 

 free margin of each plate bears an armature of seven or eight very short, robust, obtuse 

 and slightly flattened mouth-spines, the innermost of which is the largest. On the surface 

 of the plate five or six papilliform spinelets form a short, closely-placed series, parallel 

 to the median suture, which does not extend along more than half the length of the 

 plate, and the spinelets diminish in length as they recede from the mouth. The rest of 

 the surface of the plate bears small papilliform granules widely spaced. 



The actinal interradial areas are extensive as compared with the small size of the star- 

 fish, and are occupied by a large number of regularly disposed intermediate plates. The 

 plates are arranged in regular transverse series, which proceed from the adambulacral 

 plates to the marginal plates ; those adjacent to the adambulacral plate are subequal in 

 their major dimension to its length, but succeeding plates in a column diminish in length 

 as they proceed outward, and each plate imbricates slightly upon its predecessor. Five 

 or six plates may be counted in the column or series adjacent to the median interradial 

 line, and the number in a series decreases gradually as they proceed along the ray, the 

 innermost plate (that adjacent to the adambulacral) alone being present at last ; these 

 extend as far as the seventh marginal plate, which is thus separated from the tenth 

 adambulacral plate ; beyond this the adambulacral and marginal plates are contingent. 

 The surface of the plates is covered with numerous short, uniform, papilliform, spinelets, 

 rather widely spaced ; and their arrangement does not in any way simulate a paxilla. 

 The individuality of the plates is clearly defined, and the regularity of their disposition is 

 conspicuous. 



An anal aperture appears to be present in a subcentral position, but is very 

 indistinct. 



The madreporiform body is little more than its own diameter distant from the margin, 

 is hidden by paxillse, and superficially invisible. 



Colour in alcohol, a dirty ashy grey-white, with traces of a light brown shade on the 

 paxillar area. 



Locality. — Station 164. East of Sydney, New South Wales. June 12, 1874. Lat. 



