282 Verrill, Notes on Madiata. 



center of the upper surface there is a stout conical spine upon a tuber- 

 cular prominence, and around it are ten similar spines, five of which 

 correspond to the interradial spaces and five to the rays, and from the 

 latter a row of five or six similar spines extends along the median line 

 of each ray. In the interradial regions of the upper side there are 

 from three to five similar spines placed irregularly. The spines of the 

 upper surface and margin are smooth and naked, except at the base, 

 which is surrounded by a ring of crowded, polygonal, flat-topped gran- 

 ules, like those that cover the general surface. More than half of the 

 upper surface is covered by large groups and clusters of pores, which 

 occupy all the intervals between the plates and often blend together 

 into large patches on the rays. Among the pores are scattered very 

 numerous, small, short and stout, oblong pedicellariae. A few similar, 

 but somewhat larger pedicellarise occur upon the lower marginal plates, 

 either singly or in small groups. The madrepoiic plate is large ('3 of 

 an inch in diameter), slightly convex, of fine texture, placed about an 

 inch from the center, just outside of one of the ten spines that sur- 

 round the central area. 



The largest spines in this specimen are '28 long and '\b in diameter 

 at base ; they are united to the plates by a suture, which readily sep- 

 arates, when the specimens are not well preserved, leaving a smooth 

 depression, but they do not appear to have been movable. 



Color, in alcohol, deep reddish brown above, yellowish brown below. 

 When living, bright scarlet, (F. H. Bradley). 



Some of the more prominent variations from the preceding condi- 

 tion are as follows : 



2d. A specimen with the greater radius 2*3 inches. Pedicellarige of 

 lower surface smaller and less numerous ; marginal plates seven above 

 and below on each side of the rays, less unequal in size and form, with 

 small pedicellariae, very numerous on many of the upper plates, less 

 so on the lower ; lower plates mostly bearing conical spines, but some 

 having a gi'oup of three or four small rounded tubercles instead; 

 iipper plates mostly without spines or tubercles, one ray having two 

 spine-bearing plates near the end on one side, another having two on 

 each side, but not on corresponding plates, the rest without any ; a few 

 plates with groups of small tubercles, apparently where spines have 

 been broken off. Upper side with a central large spine and a row of 

 three or four spines along each ray, no spines in the interradial region. 



3d. Greater rndius 2*5 inches. Similar to the last, but the marginal 

 plates are nearly destitute of pedicellarige, and the lower ones all bear 

 a spine, while the upper ones, except one or two near the ends of the 



