REPORT ON THE ASTEROIDEA. 15 
Rays elongate, delicate and attenuate, at first diminishing rather rapidly in width 
from the base, and then tapering gradually to the extremity. Their flexibility is great, 
the outer portion being usually recurved abactinally and curled up. The lateral walls are 
vertical, and the rays nearly rectangular in section. Disk small. Abactinal surface flat, 
highest over the disk and sloping thence along the rays. Actinal surface level, slightly 
rounded at the margins. Interbrachial arcs wide and well rounded. 
The abactinal surface of the disk and rays is covered with small spicules overlaid with 
a delicate membranous tissue, and the majority bear a small but rather elongate, delicate, 
tapering, hair-like spinelet, with several minute cilia-like miliaries at the base. The 
central spines, as indeed the spinulation generally, diminish in size as they recede from 
the disk. Their delicacy on the disk is very remarkable. To a certain extent these 
spine-groups simulate paxillee, but only very superficially ; their structure and character 
being altogether different. 
The supero-marginal plates, fifty-three in number from the median interradial line to 
the extremity, are elongate and confined to the lateral wall of the ray, their upper surface, 
which is bevelled and arched, forming a very narrow border to the abactinal area. Ina 
few of the plates on the inner part of the ray the height is slightly greater than the 
length, but this proportion is soon reversed, and the length is the greater dimension along 
the rest of the ray. Each plate bears a convex elevation or low tubercule, upon which is 
articulated an elongate, delicate, tapering, and sharply pointed spine, the fourth or fifth 
from the median interradial line being the longest, measuring about 5 mm. in length ; 
and they decrease gradually in length as they proceed along the ray. There are generally 
a few short, hair-like spinelets at the base of this spine, and a few widely spaced conical 
pointed granules on the surface of the plate, in the lateral or vertical wall of the ray. 
Midway on the ray and towards the extremity the supero-marginal plates have quite the 
appearance of tubercles on rounded bases, when viewed abactinally and slightly obliquely. 
The general surface of the plate is covered with a thin membrane. 
In the median interradial line is a high odd supero-marginal plate prominently 
tubercular abactinally, upon which is borne an elongate, tolerably robust, tapering and 
sharply pointed spine, about 8 mm. in length, directed vertically. At the base of this 
spine are a few short, hair-like spines, and a few conical thornlets traverse the median 
area of the surface of the plate which falls in the vertical wall. 
The infero-marginal plates have a tendency to alternate with the superior series. Each 
plate bears a row of three, or sometimes four, very delicate, hair-like, tapering spinelets, 
along its median transverse line ; the uppermost or lateral spine is much more delicate and 
slightly shorter than the long spine on the supero-marginal plates, and the other spinelets 
decrease in size as they recede from the lateral; in addition to these there are several very . 
delicate small hair-like spinelets upon the plates, and it is frequently difficult to distinguish 
between them and the main series just mentioned. A few miliary thornlets are also 
