ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 177 



the plates decrease very g^radually toward margin and distally. Papuisc appear 

 to be all over disk, barring the narrow line of insertion of interradial septum. The}- 

 are absent from the terminal fifth of ray. Here the plates are less markedly stellate. 

 The arrangement of papula; is described in preceding paragraph. 



Marginal plates conspicuous, but partaking of the nature of large paxillse, 

 entirely without enlarged spines; a well-defined, narrow, naked groove between 

 superomarginals and abactinal paxillse. Both series with special raised ridges 

 crowned with coarse granules which increase in size toward center of ridge, where 

 they are quite heavy and similar to very much enlarged spinelets of the paxilla?, 

 though more tubercular and pointed. On inferomarginals tlie spinelets are still 

 tliicker and heavier, and increase in size toward actinal end of plate. Supero- 

 marginals, forty to forty-three in number from interradial line to extremitv of ray, 

 are much wider than long at base of ray; less so on outer part; with curved upper 

 and lower margins; the raised ridges strongly tumid, and when denuded are about 

 as thick as the adjacent intervening furrows, which are wider in the type than in 

 the other two specimens. A conspicuous longitudinal channel separates the plates 

 of the two series These furrows are not lined \vith fine spinelets as is usually the 

 case with typical fasciolar channels. The superomarginals encroach upon the 

 abactinal area, forming usually a well-defined border. The spinelets vary more 

 or less but are usually clavate and much larger on lower half of plate, where two 

 to four series on the median line have abrupt conical ti|xs. Terminal plates small 

 in largest specimen, but relatively larger in smallest; about as wide as long, broadest 

 distall}-; sometimes ovoid, at otiiers roundish; granulose; wedged between last two 

 or three superomarginals. 



At base of ray the inferomarginal plates do not correspond always exactly 

 with superomarginals, but in some cases may even alternate. The plates are tumid 

 and form a very even rounded border to actinal area, but are narrower than the 

 corresponding superomarginals (beyond interbrachial arc), hence are nearly to 

 quite quadrate beyond middle of ray; (quadrate in largest specimen, wider than long 

 in other two incluiling type). The granules as a whole are more robust than those 

 of superomarginals, but are similar in character and increase in size toward lower 

 part of plate, being mucli larger along the median transverse region than on periphery 

 of ridge. The marginal plates are, in appearance, what they are morphologically — 

 verj' much enlarged paxillje. 



Adambulacral plates, wider tlian long and rather closely placed, so that the 

 peculiarly characteristic armature forms a dense mass of spines along margins 

 of furrows. On each plate are ten to twelve robust, subcylindrical, untapered, 

 occasionally slightly compressed, truncate or round-tipped spines which decrease 

 in size as they recede from the furrow and are arranged either in five hmgitudinal 

 series of two, four series of three, or may be without regular order on outer half 

 of plate. Furrow series is commonly oblique and composed of three instead of 

 two spines; or one may stand on center of margin and two just behind it. On 

 outer end of plate five or six robust much smaller spinelets (even granules some- 

 times) form a group about the spines along the border of plate. These outermost 

 spinelets are sometimes hard to distinguish from those on adjacent actinal inter- 

 57444°— Bull. 76—11 12 



