438 THE VOYAGE OF H.M.S. CHALLENGER. 



1. Neomorphaster eustichus, n. sp. (PL LXVI. figs. 3 and 4 ; PI. LXVIII. figs. 9 and 10). 



Rays five. R = 49 mm. ; ?•= 11 mm. R<4'5 r. Breadth of a ray at the base, 10 mm. 



Rays high and broad at the base, tapering gradually to the extremity ; roundly 

 arched abactiually ; plane actinally. Interbrachial arcs subacute, with a tendency to be 

 rounded. Actinal surface plane, but deeply depressed round the mouth. 



The disk is high and a central area occupying more than half the abactinal surface is 

 distinctly depressed, the plates round its margin being on a higher level. This area 

 contains the primary apical plates, which are disposed in the following manner. The 

 centre is occupied by the dorso-central plate, external to this are five small under-basals, 

 which are succeeded by five large basal plates, slightly larger than the dorso-central ; and 

 between these and the under-basals are large isolated papulae. Outside the cycle of basal 

 plates are five large primary radial plates, nearly as large as the basals, each of which is 

 separated from its accompanying under-basal by a large papula. On the outer side of 

 the basal plates are two small plates side by side, and these with the primary radials 

 complete the outermost cycle of the depressed area. 



The rays are covered with large, subhexagonal, slightly convex plates which imbricate 

 on one another and are arranged in perfectly regular longitudinal lines, the plates dimi- 

 nishing regularly as they proceed outward. The adjacent plates of the different series are 

 equal in length and consequently form transverse series. The plates of the median radial 

 series are the largest. The plates of the next series are smaller ; and the succeeding 

 ones, which represent the supero-marginal plates, are nearly as large as the median series. 

 The infero-marginal plates, which stand vertical in the lateral wall of the ray, are nearly 

 equal to the superior series. 



All the plates of the seven longitudinal series above-mentioned and the abactinal 

 plates of the disk bear a few, large, widely spaced, semicircular, translucent granules. 



Along the rays a large papula stands opposite the suture between each plate, and 

 these form regular longitudinal lines separating the rows of plates. 



Small forcipiform pedicellarise are present on the lateral regions of the ray and also, 

 but less frequently, on the abactinal area, in the neighbourhood of the papulse. 



The adambulacral plates are small, and their armature consists of two short, thick, 

 robust, obtuse, equal spines, which radiate apart, one directed toward the furrow, the 

 other outward, and form two regular longitudinal series. 



Between the adambulacral and the infero-marginal plates is a series of elongate actinal 

 intermediate plates which bear two or rarely three short, robust, obtuse, papilliform 

 spinelets, placed side by side and forming a longitudinal series along the ray. This series 

 of spinelets coincides with the more or less angular junction of the lateral and actinal 

 surfaces of the ray, and leads at first sight to the inference that these are the representatives 

 of lateral spines and that the series of plates are the infero-marginal plates. From their 

 form and character, however, I do not consider that this is the true interpretation. At 



