I20 DISCOVERY REPORTS 



and I or 2 tubercular granules on outer end of plate. R 35 mm., r ig mm., br at inter- 

 radius 21-22 mm., at middle of ray 10 mm. 



Description. Abactinal plates not tabulate, though the radial and adradial have a 

 convex surface, which gradually flattens on interradial region, where surface of plates is 

 flush with integument — if not distorted by drying. The midradial plates are superficially 

 wider than long, not very regular, nor particularly neat and uniform in size. This series 

 reaches terminal plate. The plates of either adradial series are even less regular, are 

 irregularly oblong or squarish and the series ceases 1-3 superomarginals distant from 

 end of ray. The other plates are quite irregular and do not form well-defined series. 

 Midradial plates with 5-8 coarse, subspherical granules (the larger 0-4-0-5 mm. 

 diameter) those of distal plates often in 2 transverse series; other plates with 3-6 

 granules, according to distance from margin ; primary interradials and central with about 

 15 or 16 granules. Madreporic plate 2-5 mm. in diameter, its inner margin ^ r from 

 centre of disk. 



The abactinal plates are irregular in outline and imbricate as indicated in the figure of 

 the coelomic surface of proximal radial area. The carinal plates are slightly smaller than 

 the adradials of the 2 series at either side. Beyond these 2 series the plates become very 

 rapidly smaller and more closely imbricated as there are no papulae. On the narrow 

 part of the ray the carinals are larger than the adradials and are accompanied at either side 

 by a single series of small papulae. Proximally there are 4 irregular series of small papulae. 



The granulation of abactinal surface decreases gradually in size from the radial line to 

 margin of area. Superomarginal and inferomarginal granules successively slightly 

 larger than the peripheral abactinal, while the actinal granules are still larger and more 

 distinctly spaced. A thin skin envelops the granules. 



Superomarginal plates 17, generally a little wider than long, forming a slightly rounded 

 bevelled border to abactinal area, as do the inferomarginals to the actinal. These plates 

 are not tabulate but are individually slightly convex. Distally there is no trace of central 

 tubercles on either series. 



Adambulacral plates about as wide as length of furrow margin. Furrow spines 2, 

 coarse, compressed, prismatic, 1-5 plates long measured on furrow margin. Back of these 

 is a single, subequal, broad, round-tipped spine often occupying entire length of plate 

 and with its broad side to furrow. Outer margin with i or 2 compressed or prismatic 

 tubercles intermediate in size between the large tubercle and actinal granules. The distal 

 plates usually have a transverse series of 3 coarse spines, the median the thickest. The 

 first 2 plates sometimes have 3 furrow spines. 



Mouth-plates not convex ; with long furrow margin carrying 5 spines like the adam- 

 bulacral ; a curved series of 4 suborals rather like the outermost adambulacral tubercle. 



Two 3-valved pedicellariae are present, one on outer part of a first adambulacral 

 plate, the other adjacent to outer end of a second plate (Fig. D, le). As the jaws are 

 only slightly modified granules, flattened and somewhat excavated on the innerface, the 

 pedicellariae are very primitive. 



Type LOCALITY. St. 170. Off Cape Bowles, Clarence Island, 342 m., rock, i specimen. 



