ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 103 



Marginal plates thin. Superomarginals, fifty in number from median inter- 

 radial line to extremity of ray, nearly quadrate except in interbrachial arc, where 

 they are higher than long; plates confined to side wall, except that the upper end 

 (representing the thickness of j^late) forms a very narrow border to the paxillar 

 area. At the base of the ray the plates are vertically oriented, but bej'ond the 

 basal 0.4 they slope upward and mesially (together with the inferomarginals), thus 

 forming a steep bevel. At the end of ray the inferomarginal plates with their 

 spines define the contour of ray. Each plate is slightly tumid and bears a rigid, 

 erect, robust, tapering spine, at about the middle of the abactinal end, and approxi- 

 mately as long as the height of plate. These spines decrease in size distad, and 

 are apparently lacking on the last few plates. General surface of plates covered 

 with very small papilliform spinelets, which are spaced and slenderer at edges of 

 plate than in center. No fasciolar channels. Terminal plate longer than \vide, 

 notched toward paxillar area, and aj)parently covered with fine spinelets, although 

 these are rubbed off. 



The inferomarginals correspond plate for plate with superomarginals (except 

 at extreme tip of ray, where there is one additional plate) and the slight tumidity 

 of the latter merges into that of the former without a break at intermarginal 

 suture, and the spinelets are also the same, but increase m size toward inner and 

 lower edge of plate, being more widely spaced on the actinal surface. The plates 

 encroach slightly onto actinal surface, forming an abruptly rounded border, about 

 as much of a ])late belonging to lateral as actinal surface. In center of each stands 

 a tapering rigid spine, forming a series all along ventro-lateral margin, and extend- 

 ing outward at right angles. These are a trifle longer than corresponding supero- 

 marginal spine. On first two inferomarginals (by a slip of the pen, erroneously 

 stated superomarginal in original description) is an additional spine between the 

 regidar sjjine and actinal margin of plate. The superomarginal and inferomarginal 

 series of spines are very regular. 



Adambulacral plates much longer than wide, with a slightly curved furrow 

 margin. Armature consists of (1) a furrow series of ten (eight or nine sometimes) 

 fragile, slightly tapering, round-tipped, faintly compressed spinelets, which are 

 slightly bent at the base and graduated toward either end of the series. (2) On the 

 actinal surface just behmd the furrow series is a longitudinal row of about nine 

 much .shorter, thick, clavate spinelets, and on the outer edge of the plate is a series 

 of delicate, slender tapering, papilliform spinelets wloich follow the contour of the 

 plate and are smaller than the other series. On the outer i)art of ray the plates 

 become very narrow, and although the spinelets are mostly rubbed ofi", two or 

 tliree plates near the tip still retain an enlarged actinal spine. Only the distal 

 most plates seem to have this. 



Mouth plates large, prominent actinally, and the united j)air broadest at 

 middle, but only slightly narrower at outer end; lateral margms toward furrow 

 slightly excavated, and the end toward actinostome truncate. (Unfortunately the 

 armature in the specimens exanuned has been largely rubbed off.) Marginal series 

 much like that of adambulacral plates, and consisting of about fourteen spines, 

 compressed and curiously expanded above the slender base, from this expansion 

 tapering to the extremity. These spines seem to increase in size toward the inner 



