ASTEROIDEA OF H.M.S. ' CHALLENGEE ' ErPEDITIOK. 221 



often to a lengtli equal to that of tlie spinelet itself. Aper- 

 ture-papillai moderately large, elongate and suboval. A fleshy- 

 thickening or pad is developed on the surface that fits over the 

 aperture, upon which it closes like a valve. 



The mouth-plates are of moderate size, widely expanded 

 laterally, the keel along the juuetiou being well developed, 

 prominent aborally, and with a rather produced peak adorally. 

 Two secondary surface-spines on each, plate — one near the adoral 

 extremity, the other, shorter and more robust, midway on the 

 plate and with wide-flaring investment. It is a question whether 

 the anterior pair ought not, from their position, to be ranked 

 with the true mouth-spines. Mouth-spines proper 3 to 4 in 

 number, acicular, and placed on the margin of the lateral 

 flange. 



Actino-lateral spines closely placed, and entirely hidden in the 

 thick fleshy membrane with which the yentral interbrachial areaa 

 are uniformly covered. 50 to 60 spinelets on each side of a ray. 



Colour, in alcohol — dorsal surface purplish grey, actinal surface 

 pinkish purple. 



Station 295. Lat. 38° 7' S., long. 94° 4' W. Depth 1500 

 fms. ; bottom temperature 1°'4 C. ; red clay. 



Htmenaster GLAtrcus, n. sp. 



Marginal contour stellato-pentagonal ; interradial angles well 

 indented, forming a distinct angle, except in very large specimens, 

 where the web has become somewhat overgrown and abnormally 

 thickened. Minor radial proportion from 68 to 76 per cent. ; 

 jK=46 millim., r=35 millim. The rays taper to a fine extremity ; 

 and the web is rather full on the margins, and somewhat irregular 

 in consequence. General form very depressed. On the dorsal 

 surface the radial areas are well marked out, distinct from the 

 fringe and interbrachial membrane, by a regular linear arrange- 

 ment of paxillse-spinelets, the radial areas being elevated above 

 the general surface. The pseudo-sides of the rays are short and 

 perpendicular; the rays themselves having the appearance of 

 standing in relief above the superficies of the marginal and inter- 

 brachial web, tapering to a fine point, and maintaining their dis- 

 tinctness up to the very extremity. The lateral web or fringe is 

 largely developed, and, being rather full, is in consequence some- 

 what irregular. 



Supradorsal membrane with very numerous muscular fibres, 



