246 ASTEEOIDEA OE H.M.S. ' CHALLENGES,' EXPEDITION. 



The papulae are simple round sacs, as broad as long, and im- 

 mensely large in proportion to the pedicels by whicb tliey stand. 



Dorso-marginal plates are present at the extremit}^ of the ray, 

 and form a terminal arch or ocular guard ; but they are not half 

 the length of the similar pieces in the preceding species, 



Ambulacral furrows wide, not petaloid ; margins of the furrow 

 very narrow. Ambulacral spines 2 or 3, placed very obliquely, 

 the inner or aboral spine the smallest; whilst the outermost 

 spine is probably the representative of the aperture-papilla, 

 of which it occupies the place, although it differs in no way 

 from the other two spinelets ; sometimes a small additional 

 spinelet is present. The spines are long, delicate, and needle- 

 shaped ; and there are traces of a fine investing membrane. 



The mouth-plates are of the Symenaster type, and present a 

 prominent peak aborally, sloping adorally, and little promi- 

 nent in front. Each plate bears two, long, clavate, thorny, 

 somewhat curved secondary surface-spines, nearly equidistant 

 from one another and from the extremities, and rather wide away 

 from the keel or median suture, the posterior spinelets being 

 longest. Two mouth-spines proper are situated on the horizontal 

 margin of each plate, the innermost one being slightly smaller 

 than the anterior secondary (surface) spine, which it resembles 

 exactly both in form and character; whilst the outer spinelet is 

 very much smaller, and slightly tapering and smooth, instead of 

 being clavate and thorny. 



Actino-lateral spines delicate, rather widely spaced, about 15 

 on either side of a furrow, the 4th or 5th from the mouth being 

 longest. The spines diminish slowly in size as they proceed out" 

 ward, and maintain a fair length even at the extremity of the ray. 

 The actinal membrane is perfectly transparent, and composed of 

 very fine and widely spaced fibres, reticulated ather rectangu- 

 larly. No marginal fringe is formed; and the actinal tissue 

 appears to pass over the margin continuous with the dorsal tissue. 

 The actino-lateral spines project considerably beyond the margin, 

 and are naked. 



Colour, in alcohol, greyish white. 



Station 218. Lat. 2° 33' S., long. 144° 4' E. Depth 1070 fms. j 

 bottom temperature 2°'l C. ; Glohiget^ina-ooze. 



