Yerrill, JVbtes on Radiata. 283 



rays are without spines or tubercles. Foui- of the interradial regions 

 of the upper surface have each a single large spine near the margin, 

 and one of them also a small one inside the madreporic plate ; the fifth 

 has no spine. 



4th. Greater radius 3 inches. Lower surface with very few large 

 pedicellariae, eight lower and seven upper marginal plates, the outer- 

 most two the most swollen ; all the lower plates bearing a spine ; two 

 or three of the upper ones near the ends of the rays bearing small 

 spines, and many of them with a few scattered pedicellariae. Central 

 dorsal spine surrounded by ten spines, and only one of the interradial 

 regions having a spine near the margin. Five or six spines along the 

 middle of the rays. 



5th. A specimen of the same size as the last. Lower and upper mar- 

 ginal plates without tubercles or spines, except two or three of each 

 at the end of each ray, which bear small spines ; most of them bearing 

 scattered, large, oblong, sessile pedicellariae. Interradial regions with 

 from four to seven large, sharp spines. 



6th. The largest specimen, with the greater radius 3"75 inches. 

 Lower surface nearly destitute of pedicellariae, a few very small ones 

 on most of the upper marginal plates. The latter are more uniform 

 in size and shape than usual, from three to five of the outermost 

 bearing small spines, the rest without spines or tubercles, except that 

 one of the middle ones, on three of the interradial margins, bears 

 a spine. Central dorsal spine surrounded by ten spines, with two 

 other spines irregularly placed within the ring. The median row of 

 spines along the rays has from seven to ten spines. The interradial 

 regions bear from nine to thirteen spines in unequal, but somewhat 

 regular, groups. 



7th. A specimen, having the greater radius 3-3 inches, has groups 

 of from six to eight interambulacral spines in the iinier row. Each 

 of the interradial spaces beneath bears from two to six stout, unequal, 

 irregularly placed pedicellariae. There are eighteen lower and sixteen 

 upper marginal plates along each interradial margin, all of which are 

 destitute of pedicellariae. Each of the lower ones bears a short, blunt 

 spine, largest near the end of the rays. The three upper plates near- 

 est the ends of the rays alone bear spines, the rest are evenly granu- 

 lated. There are from seven to nine spines along the median ridge of 

 the rays and from four to six, regularly placed, in the interradial 

 regions. Besides the usual ten spines around the central one, there 

 are four others, forming an imperfect inner circle around it and corres- 

 ponding to four of the radial rows. 



