Of THE AIElUiUI ARCHIPELAGO. 



90 



the iuterbrachial areas and on the mouth-shields. Lower arm- 

 plates white, with a small patch or line of purple on either side 

 of the median line. Every four or five plates with more colour 

 than the others, giving a banded appearance to the naked eye. 

 Locality. Elphinstone Island. 



Ophiothrix variabilis, sp. nov. (Plate IX. figs. 18, 19 ; 

 Plate XI. figs. 32-36.) 



The disk is either circular or slightly pentagonal in outline, 

 large, tumid above, covered with a skin (sometimes crumpling 

 when dry) with very small scales, each bearing a short, stout, 

 cylindrical, but slightly tapering stump having a crown of very 

 small thorns, three to six (usually four) in number. About six 

 rows of these scales with stumps in the interradial areas, and a 

 crowd in the centre of the disk and at the margin in the interradia. 

 Between the radial shields three rows of stumped scales. E-adial 

 shields large, longer than broad, projecting much over the arm, 

 naked, granular, and with a few very low rounded knobs, especially 

 towards the outer end. 



Below, the disk has a skin in the iuterbrachial spaces extending 

 to the adoral genital plates, which are attached to the mouth - 

 shields aborally, covered with minute scales and rather crowded 

 with slenderer stumps than above, and with one thorn only ; they 

 diminish in numbers towards the mouth-shield. 



Genital plate in contact with the underpart of the radial 

 shield aborally, and also articulating with a large, broad, wavy- 

 edged genital scale. Mouth-shields small, broader than long, 

 somewhat angular adorally or trilobed there. Side mouth-shields 

 small, largest at the outer sides, narrow, and separated adorally 

 to the mouth-shield, and not extending beyond the level of the 

 long diameter of the mouth-shield aborally, Jaw-angles short, 

 broad, separated by a considerable space, with a large tentacular 

 area. Jaw-plate large, projecting slightly downwards, with 2b* 

 or more tooth-papillae, the two highest being like a divided tooth, 

 the rest large and long, except those placed near the lower 

 margin of the plate, which is rather truncated. Teeth four. 



Lower arm-plates narrow and grooved within the disk, square a 

 little further out, then longer than broad, the length gradually 

 increasing towards the tip of the arm. At a short distance from 

 the disk they are slightly incurved at the aboral edge and curved, 

 convexity adorally; the sides nearly straight or slightly incurved, 



