REPORT ON THE ASTEROIDEA. 59 



the length slightly greater than the height. They are tumid along their breadth, with a 

 distinct but shallow channel between each, the course of which is slightly oblique from 

 within outwards. Each supero-marginal plate bears a single robust, dumpy, obtusely 

 rounded, and very short spinelet, little more than an elongate tubercle, which is situated 

 just over the rounded angle of the plate, and quite on the lateral side. These tubercles 

 are present on every plate up to the extremity, excepting only the innermost plate on 

 one side of the median interradial line in each interbrachial arc, viz., the left-hand plate 

 (regarded from the centre) in the odd posterior and the left postero-lateral interradia, 

 and the right-hand plate in the other interradia. The general surface of the supero- 

 marginal plates is covered with very minute and widely-spaced conical granules. 



The infero-marginal plates are similar in size and character to the superior series ; 

 each bears a short, robust, and rather bluntly pointed lateral spine, the longest not more 

 than 15 mm. Behind this, in the median line of the plate, are two or three much smaller 

 and sharply pointed spinelets, that nearest to the lateral spine being the only one worthy 

 of the name — the others, when present, for they are not traceable on the outer part of the 

 ray, being merely thornlets slightly larger than the small widely spaced thornlets which 

 cover the general surface of the infero-marginal plates. 



The adambulacral plates are large and broad, with a semicircular margin projecting 

 into the furrow. Their armature consists of : — (1.) A furrow series of six short, slightly 

 tapering, delicate spinelets, the outermost on each side the shortest, arranged on 

 the furrow margin, radiating slightly apart, and forming a fan when directed over the 

 furrow. (2.) A short, robust, conical spinelet, not much longer than the largest furrow 

 spinelet, but much more robust, placed on the actinal surface of the plate, usually with a 

 small thorn -like spinelet on each side near the margin ; and there are no other spinelets 

 on the plate. 



The mouth-plates are rather small, convex actinally, and with an open median suture. 

 The free margin of the united pair has an almost semicircular contour, and its armature 

 consists of seven or eight small, short, slightly tapering spinelets on each plate, which 

 increase slightly in length as they proceed inward, the innermost pair being conspicu- 

 ously the most robust, but only a little longer than the adjacent spines. There are 

 three or four small spinelets on the actinal surface of the plates arranged parallel to 

 the median suture, and two or three on the outer portion. Very few of the actinal 

 spinelets now remain on the plates, but their former existence is indicated by the small 

 tubercles on which they were articulated ; all appear to have been very small, and I 

 am unable to distinguish any as large as the outer or actinal spine on the adambulacral 

 plates. 



The actinal intermediate plates occupy a very limited area, and do not extend beyond 

 the fifth adambulacral plate in the largest specimen, about sixteen being present in the whole 

 area. In a smaller example the number is much less, and their extent still more limited. 



