Verrill, JVbtes on Radiata. 373 



bearing a large, suu)oth sjtiiie. Tntcrninhiilacral ))lat('S ht'ai'iiig a row 

 of smaller, iniKH" spines, several on eacli plate, and an outer serii's of 

 larger ones, oni^ to eaeli j»late. 



This genus is nearly allied to Ori'<(Mei\ and still more so to JVido- 

 relUa. From the foi-mer it differs in its depressed form, tessellated, 

 })olygonal [)lates, the character of the spines, etc. ; from the latter, in 

 the larger and less numerous plates of the upper surface, consisting 

 mainly of the three median rows of the rays, with very few in the 

 interra<lial regions, while in N^idonllia they are much inor(> numerous 

 and the interradial regions of the u})per surface are well develoi)ed. 

 The marginal plates, also, in the single known s])ecies, are granulated 

 only around the mai-gin, 



Amphiaster insignis Verriii, sp. nov. 



Plate IV, figure 1 0. 



Proportion of the radii of rays to those of the disk, nearly as 2 : 1. 

 Rays broad at base, small, but not acute, at the tips, with the interra- 

 dial margin deeply and regularly incurved in young specimens, slightly 

 angular in larger ones. Along the upper side of the rays, there are 

 three rows of regular plates, which are rathei* large and somewhat 

 prominent, and each normally bears a large, sharp, conical spine, 

 smooth above, but surrounded by granules at the base. These s])ines 

 form, therefore, three regular rows on the rays, except near the tips, 

 where the lateral ones become obsolete. The spines increase in size 

 toward the center. The five inner ones of the median rows are often 

 absent, the corresponding plates presenting a smor)th, rounded sur- 

 face, as if the spines had been broken off and the scars had healed 

 over ; frequently, also, several of the other median s])ines are wanting 

 in the same way ; but the numljer and positions of the naked plates 

 differ on the different rays of the same individual, and on different 

 specimens. In each angle l^etween the inner ends of the median rows, 

 and terminating the lateral ones, there is a larger spine, forming the 

 angles of a pentagonal area, enclosing from three to five similar spines. 

 The lai'ge madreporic plate is outside tliis area, close to the base of one 

 of the spines. In the interradial regions, and surrounding the ovarial 

 openings, there are about five small plates, one or two of which often 

 bear spines in the larger spccamens. The margin is rounded, and 

 formed by both the upper and lower series of plates, those of each 

 row alternately approaching and receding from the margin. These 

 plates are variable in size, those of the upper series much the largest, 

 somewhat rounded, and in the intervals between those that are se]ia- 

 rated there are often small accessory plates, and at the angle there is 



