Sladen — Echmodermata from the S.W. Coast of Ireland. 697 
tissue. The spiracula, which are small, are moderately numerous, and 
usually isolated, that is to say, one only in a mesh. The paxillse 
appear to have norm.ally three spinelets, which are aggregated close 
together, so as to form a crown of small expansion. The paxill^e are 
widely and equidistantly spaced, and a more or less distinctly longi- 
tudinal arrangement may be observed. The tips of the spinelets 
protrude prominently, and the muscular fibres are not tightly stretched, 
but hang like slackened ropes round a tent-pole, the tips of the spine- 
lets appearing in consequence like conical prickles upon the abactinal 
surface, those on the central half of the disk being especially long and 
prominent. 
The oscular orifice is very large and conspicuous ; the valves are 
formed of large robust spinelets, the longest measuring about? 16 mm. ; 
and all are united by a thick fleshy web, which gives a tubular charac- 
ter to the structure when the spinelets of the valves are erect. 
The ambulacral furrows are very wide throughout, and are only 
slightly constricted until quite near the extremity. The armature of 
the adambulacral plates consists of two rather short, conical, tapering 
spinelets, about 3- 5 mm. in length, and robust at the base, covered with 
membrane which forms a full, wide, terminal sacculus, extending for a 
distance greater than the length of the spine beyond the tip. Both 
spines are placed on the furrow margin of the plate, and radiate slightly 
apart. The aperture-papillae are large, and have a wide and elongate 
sacculus, which gives them the appearance of an elongate, uniformly 
broad flap with obtusely -rounded extremities. 
The mouth-plates are large and conspicuous; widely expanded 
laterally, the keel along the junction being high and abrupt and 
prominently produced aborally, and with a small abrupt peak adorally. 
Each plate bears a robust secondary or superficial spine on the side of 
the keel about one-third of the distance from the adoral to the aboral 
extremity of the plate, and a second similar spine stands near the 
adoral margin. The mouth-spines proper are three in number, short, 
robust, and conical, placed on the margin of the lateral flange of the 
plate. 
The actino-lateral spines are long, robust, and widely-spaced, tending 
to meet the corresponding spines of the adjacent ray in the median 
interradial line, where there is much thickening and excrescent growth 
near the margin. 
Colour in alcohol a dirty, yellowish, ashy-grey, with purplish traces 
on the actinal surface. 
Mr. W. P. de Y. Kane, who made a number of admirable drawings 
3 D 2 
