Sladen — Echinodermata from the S. W. Coast of Ireland. 689 
The supero-marginal plates, which are eight in numher, counting 
from the median interradial line to the extremity, form a broad and 
conspicuous border to the abactinal area, the breadth of which at the 
median interradial line is about 3-75 mm. ; and it diminishes very 
•slightly towards the extremity of the rays. The plates near the inter- 
radial line have their breadth fully twice their length. The length of 
the plates is equal up to the fifth and then diminishes, the breadth 
being greatly in excess throughout. The ultimate plate is very small 
and wedge-shaped, with the apex directed towards the median radial 
line. The surface of the plates, which is slightly convex in the trans- 
verse direction, is entirely covered with rather large, low, uniform, 
flatly hemispherical granules which, though closely placed, are not so 
crowded as to modify the form of the granules. The odd terminal 
plate, though very small, is larger than the ultimate supero-marginal 
plate ; it is shield-shaped or subcordiform, with the apex adcentral, 
and thickened and turned abactinally towards the outer margin. 
The infero-marginal plates, which are nine in number, counting 
from the median interradial line to the extremity, correspond to the 
superior series for two or three plntes on each side of the median inter- 
radial line, but alternate with them along the outer part of the ray. 
The breadth is about twice the length at the median interradial line, 
but diminishes gradually up to the antepenultimate plate, where the 
proportions are subequal. The infero-marginal plates are covered with 
granules similar to those on the superior series. I have not detected 
the presence of pedicellariae on either series of marginal plates. 
The adambulacral plates are rather broader than long. Their arma- 
ture consists of a marginal series of six, rather short, obtusely pointed 
or rounded spinelets, which are flattened transversely, and with a 
tendency to become prismatic ; the adoral spinelet being much shorter 
than the others, and placed further back on the plate. The marginal 
series is followed by a second regular series of three short, robust, 
prismatic, pointed papilliform spinelets ; and the outer part of the plate 
is occupied by three series of three uniform papilliform granules. 
These granules are usually regularly placed as above described, but 
occasionally a little irregularity occurs. They are intermediate in size 
between the very short papilliform spinelets of the second series, which 
are little more than elongated granules, and the true granules of the 
{ictinal intermediate plates. I^ear the outer extremity of the furrow 
one of the papilliform spinelets of the second series becomes very large 
and robust. I have found no pedicellariae on the adambulacral 
plates. 
