SEA LILIES, STAHFISHES, ETC. — CLAEK. 45 



and 3 mm. thick), to within 15-20 mm. of the centre of the 

 disk ; distally these plates are much like the other abactinal 

 plates and are about 2 mm. in diameter ; near the middle of 

 the arm and proximal to it they become compressed and 

 are much wider than long (3-4 mm. wide by 1.5-2 mm. long), 

 but the 4-6 most proximal are again more or less nearly circular ; 

 these circular proximal plates are the largest of the disk and 

 are very much swollen ; the most proximal, which is largest, 

 is 5-6 mm. in diameter and 3 mm. or more high ; on these big 

 proximal plates, the central granule becomes developed into 

 a huge spine, 2 mm. in diameter ; only one of these persists 

 in the specimen at hand ; that is on the fourth plate of one of 

 the radial series and measures 3 mm. in height. The median 

 radial plates are accompanied nearly, and sometimes quite, 

 to the terminal plate, by a series of similar, but smaller and 

 less conspicuous plates, without spines. At the centre of the 

 disk, and in each interrachus, in line \\'ith the most proximal 

 of the big radial plates, are enlarged plates, which apparently 

 bore spines. The circular madreporite, 4 mm. across, lies 

 just distal to one of these large interradial plates. 



Superomarginal plates 25-26 on each side of each ray, more 

 or less bare and smooth, and distinctly swollen ; each plate is 

 surrounded by a series of flattened granules : the plates in the 

 interbrachial arc bear a vertically elongated cluster of spherical 

 granules, among the lower ones a stout spine ; on the first supero- 

 marginal (adjoining the interradial hne), this spine is about 

 6 mm. long and a milhmeter thick at base ; each succeeding 

 plate has fewer granules, and the spine becomes stouter and 

 stands nearer to the centre of the plate ; at the middle of the 

 arm, the spine may be 2 mm. in diameter and there are 

 virtually no granules on the plate ; distally the spines become 

 steadily smaller ; in the present specimen none are left distal 

 to middle of arm ; occasionally one, or even two, of the 

 granules on the plate are replaced by the big, characteristic 

 pedicellarise. Inferomarginal plates one more in number than 

 the superomarginals and hence not corresponding exactly in 

 position, except at each end of the series ; very similar in 

 appearance but with more granules (especially at oral end, in 

 interradial arc) and (to judge from the single one remaining) 

 with more slender spines. 



Actinolateral plates wanting on distal half of ray ; the first 

 series (adjoining adambulacrals) begins at about the ninths 

 or eighth, inferomarginal (counting from interradial hne) ; 

 the second series begins at the third inferomarginal and a 

 third series at the second ; the rest of the large actinal area is 



