132 NATURAL HISTORY BULLETIN 



ing only a little smaller. The first plate usually has the spine 

 rudimentary or lacking. Below the base of these spines there 

 are proximally usually two or three small, acute, secondary spines. 

 The surface of the plate is covered rather thickly with short, 

 acute, erect spinules; those below the spine are longer. The 

 sutures between the plates are wide, but only feebly fasciolated. 



The inferomarginal plates are thick and form a strong raised 

 border to the under side of the disk and rays, which appear 

 sunken below the border. These are more strongly spinulose 

 than the upper ones, especially on the outer part, where the 

 spinules become large and sharp. Each of the plates bears one 

 large marginal spine, similar to the dorsals, but rather longer. 

 Below this, on the proximal plates there is a double group of five 

 or six secondary spines, one or two of them about half as long 

 as the large one. More distally these become reduced to two or 

 three. These and the coarse spinules between them give the 

 under surface a very spinose appearance. 



The adambulacral plates have a very prominent inner angle 

 which bears a row of eight to ten slender graded spines, contin- 

 ued around the actinal edges by more slender spinules. On the 

 actinal face are borne proximally either a single large tapered 

 spine, or else two unequal spines; in the latter case the smaller 

 spine may be on the aboral or on the adoral side of the larger 

 one. The plates with two spines may alternate irregularly with 

 those with only one. Beyond the middle of the ray most of the 

 plates bear two nearly equal spines. 



The interactinal plates form, on each area, one row of about 

 eight plates, and a shorter row of four or five small plates. 



Pectinate pedicellarije, broad ovate in form, with raised bor- 

 ders, are present over the sutures between part of the larger in- 

 teractinals. There may be from one to four on each area; most 

 often two; sometimes none. These plates also bear a central 

 spine, with basal spinules around it. Peroral spines are rather 

 large and stout. 



These specimens are considerably larger than those seen by 

 Perrier, but they differ little except in those features naturally 

 due to increased age. In my specimens the character of the 

 papular areas is that of typical Cheiraster, and not at all like 

 Pectinaster, in which Lud^^ag placed the species. 



