438 THE VOYAGE OF H.MS. CHALLENGER. 
1. Neomorphaster eustichus, n. sp. (Pl. LXVL figs. 3and 4; Pl. LXVIII. figs. 9 and 10). 
Rays five R=49mm.; r=11mm. 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 abactinally ; plane actinally. Interbrachial ares 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 followmg 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 papulze. 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 age radials 
complete the outermost cycle of the depressed area. 
The rays are covered with large, subhexagonal, slightly convex plates which sibvieate 
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. he 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 pedicellariz are present on the lateral regions of the ray and also, 
but less frequently, on the abactinal area, in the neighbourhood of the papule. 
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 
