80 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



to slightly longer than pedicel, the whole about 1 mm. high. Each 

 paxilla has a broadly elliptical base and 5 to 8 spinelets, of which one 

 usually occupies the center, except on the distal half of the ray, where 

 the paxillae are smaller, and have 4 or 5 spinelets, or at tip as few 

 as 2. There is usually, but not always, a slight prominence at center 

 of disk. The papulae extend about half the length of ray. Scat- 

 tered over abactinal surface are fairly numerous pedicellariae borne 

 on special plates, and Avith usually 4 spiniform jaws nearly as thick 

 as the pedicel of a paxilla. 



Superomarginals (36 to 38) dorsal in position (the upper ends of 

 the inferomarginals forming the margin to ray) and forming a con- 

 spicuous, slightly rounded border to the paxillar area. The plates 

 are proximally wider than long but on outer portion become slightly 

 longer than wide. They bear no special spines but are covered with 

 slightly spaced lanceolate pulpy spinelets very sharp on central por- 

 tion of plate (where they are directed toward end of ray), but blunt 

 on the edge. Here they close over the deep fasciolar grooves, lined 

 with capillary spinelets. As in the case of the paxillae, the calcareous 

 spinelet is really very delicate and the various proportions and shapes 

 of the superomarginal papillae are due to the membranous invest- 

 ment. 



Terminal plate fairly large, notched at tip and with deeply con- 

 cave margin toward paxillar area. The surface is covered with 

 minute spinelets, and in addition 8 needlelike spines, 4 on either 

 side at the tip, the 2 central ones of each series being the longest, and 

 usually a little longer than the plate, as seen from side. 



Inferomarginals extending laterally beyond superomarginals about 

 half the width of the latter and forming a beveled border to actinal 

 surface. The width of the plates equals about the length of 2, in- 

 cluding the fasciolar groove. General surface covered with large 

 spaced pulpy lanceolote spinelets which abactinally become much 

 smaller and grade into the superomarginal spinelets. These spinelets 

 are directed outward and aborally, and are usually sharp, except at 

 inner end of plate. Lateral spines, usually 2, the outer and upper (on 

 the upper end of plate) the longer (equaling 2.5 plates in length) 

 tapering, flattened, and very sharp. The second, about two-thirds to 

 three-fourths the length of the first, is spaced from it slightly, and 

 is much slenderer and more nearly cylindrical, although flattened 

 obviously at the base. Rarely a smaller spine makes a third in this 

 series. Rather nearer the inner edge of plate than base of second 

 lateral spine, is a much shorter and more delicate spine, which is 

 well-developed only on the proximal half of the ray. It is analogous 

 to the inner inferomarginal spine of A. phragmorus. 



Ambulacral furrow wide; tube feet large, with sharp point. 

 Adambulacral plates with wide sutures and strongly convex furrow 



