OF THE MERGUI ARCHIPELAGO. 



95 



The variability is remarked by Mr. Lyman in his Report on 

 the 1 Challenger ' Ophiuroidea, p. 170. 

 Locality. Owen Island. 



Genus Ophiotheix, Mull. Sf Trosck. 



Ophiothrix Andersoni, sp. nov. (Plate IX. figs. 12, 13 ; 

 Plate XI. figs. 28-30.) 



The disk is circular in outline, large and tumid. The radial 

 shields are large and naked. Minute scales with slender 2- to 

 4-thorned stumps in the centre of the disk, between the radial 

 shields and the pairs of shields. A single series between the radial 

 shields of a pair and four close rows in the interradial spaces. 

 Scales overlap the radial shields somewhat. Similar small scales 

 and stumps at the margin of the disk. Below, the disk is covered 

 with minute scales bearing stouter stumps than those above and 

 with five to eight long thorns to a stump. 



Mouth-shields small, much broader than long, more or less 

 elliptical, but angular within and rounded without. Side mouth- 

 shields small, largest at their sides, and meeting in front of the 

 mouth-shields by a narrow edge. Jaw-angles short, very broad 

 close to the side mouth-shields, with a small opening at the 

 median line and large tentacular orifices. Tooth-papillae and 

 teeth, the former in an ovoid space, small and crowded inferiorlv ; 

 lower ends of the ovoids very wide apart from those opposite, so 

 as to produce a funnel-shaped mouth. 



Arms broad, arched, high and long, ten times the diameter of 

 the disk in length. Lower arm-plates broad and flat; some, 

 within the disk, are longer than broad, but the breadth gradually 

 increases over the length ; they are broadest aborally. The 

 plates near the disk have the outer edge much curved, convexity 

 towards the tip of the arm, and the edge within is slightly incurved. 

 Further out in the arm the plates become longer than broad, and 

 are slightly convex at both of the edges as well as curved out at 

 the sides. A broad purple baud passes down the under arm, 

 which has a white colour. 



The upper arm -plates are convex from side to side, much 

 broader than long, short, broadest and curved at the aboral edge 

 and narrower and incurved adorally ; sometimes the aboral edge 

 has a slight incurve at the median line. The breadth diminishes 

 in relation to the length towards the tip of the arm. The colour 

 of the plates is a smalt-purple, and a narrow white band crosses 

 each plate. The first plate has a few thorned stumps on it. 



S* 



