332 BULLETIN "76, UNITED STATES NATIONAL MUSEUM. 



Mart^inal plates conspicuous; about fourteen to twenty prominent, compressed, 

 rather widely space<l, transversely oriented, paxilliform plates represent the infero- 

 marginal series, and between any two of these in the same linear series are one to 

 three, usually two, long:itudinally oriented, much lower and slightly smaller plates 

 representing the superomarginal series, although now forming a single series with 

 inferomarginals. The prominent marginals become more conspicuous toward tip 

 of ray, acquiring a heavy, compressed pedicel often higher than its width at top 

 and very paxilliform in appearance, bearing two transverse rows of about eight to 

 sixteen tapering needle-like spines one and a half to twice as long as the pedicel, 

 wliich increase in length but decrease in number toward extremity of ray. Beyond 

 proximal fourth of ray there are two well-defined series of these spines, of which 

 the adoral are the shorter, and in the other series about three skin-covered spines 

 become much larger than the rest and have very sharp points. Distally the spines 

 form two palmate series, but there is more or less variation in their numbers. The 

 nonprominent longitudinally oriented plates vary considerably in size and decrease 

 markedly in size distad, whereas the others become more prominent. Except at 

 base of ray they are not nearly so high as transveree plates and are rounded to 

 elliptical-oblong, bearing upward to twenty-five very short spinelets in about three 

 or four longitudinal series. At tip of ray these plates are very small, bearing a 

 group of five or more delicate spinelets. 



Actinal interradial areas small, with small, closely placed, paxilliform plates 

 bearing four to ten spinelets, which are more delicate than those of abactinal paxillae, 

 although the latter are of about the same size. Interradial paxilliE about ten to 

 twenty in number. Proceeding along ray almost to its tip is an inconspicuous 

 series of very small actinal intermediate plates, often rather widely separated, a 

 plate usually opposite each adambulacral plate, and distally bearing only a single 

 small spinelet, or none at all, proximally with two to five spinelets. 



Adambulacral plates mth a palmate furrow series proximally of six to eight, 

 distally of four or five, very delicate, tapering sharp skin-covered spinules united 

 for about a third their length by a web. ilesial spinules longest (about one-third 

 width of plate in length), thence decreasing in length toward either end of series. 

 On actinal surface of plate is a transverse comb of four or five slender, needle-like 

 sharp spines, the two or three mesial the longest, the inner usually sUghtly longer 

 than furrow spinules though often nearly twice as long; outermost spine usually 

 nearly equal to the longest, which exceeds in length width of plate. These spines, 

 like those of furrow series, are invested in membrane, wliich forms vane-like lateral 

 expansions (causing the spinule to appear broad and fiat near base) and unites them 

 in a common web by their bases. On distal part of ray the largo adambulacral 

 spines are similar in size and appearance to the larger inferomarginal spines already 

 described. 



Mouth plates of the usual shape, rather prominent actinally. Each plate has 

 three long sUgbtly-tapering pointed spines at inner end, these decreasing in size out- 

 ward, so that tliird spine is about one-half length of iimermost; thence the series 

 is continued to end of plate in seven or eight much shorter spines resembling those 

 of first adambulacral plate. All spines are skin-covered and united basally by a 



