700 Proceedings of the Royal Society 
spinelets, — 5 or 6 in the midst of each crown more robust than the 
rest. 
Marginal plates large and conspicuous. Supero-marginal series 
about as broad as high, 33 in number from the interbrachial angle to 
the extremity, covered with granules which become subconical in 
form on the lateral half of the plate. Each supero-marginal plate 
bears a single, moderately long, conical, pointed spinelet standing on 
the rounded angle of the plate and directed outward almost 
horizontally. Sometimes this spinelet may be reduplified on two or 
three plates near the middle of the ray. Infero-marginal plates cor- 
respondent with the superior series and similar in every respect, 
covered with similar sub-conical granules, and each with a similar 
and equal sized spinelet directed horizontally. The supero-marginal 
spines diminish in size towards the interbrachial angle and towards 
the extremity ; and also the infero-marginal spines, but in a less 
degree. The largest spines are consequently about midway on the 
ray. Adambulacral plates form a straight or very faintly festooned 
margin to the furrow. Ambulacral spines rather elongate, 10 in a 
lineal series on the furrow-margin of the plate, slightly compressed, 
not tapering, extremities rounded, the middle spines largest; the 
others diminishing by gradation to either end of the series, the outer- 
most spine being small and setiform. External to this inner row 
stands a single large, conical, sharply pointed spinelet, nearly as 
large and robust as the marginal spines. A few minute setiform 
spinelets stand at the base on the outer portion of the plate. 
Interbrachial areas large. The ventral plates are small, numerous, 
regularly quadrate, and are divided into lineal series or columns by 
furrows which extend from the adambulacral plates to the marginal 
plates, — the breadth of the columns at their inner extremity corres- 
ponding with that of the adambulacral plates, but contracting as they 
proceed outward, in consequence of the diminution of the size of the 
plates. The ventral plates are covered with papilliform granules or 
spinelets, and each of those in the angle bears a single, moderately 
robust, conical pointed spinelet springing from the midst. 
Anus distinct. Madreporiform body obscure, hidden by paxillse ; 
probably situated in the midst of a circular area of more widely 
spaced paxillse which occurs in one of the interradia, rather nearer 
the margin than midway. 
