ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 151 



secondary plates have two or three lobes and all plates touch and usually join by 

 these. Outside the papular areas the abactinal plates are roundish, anil far along 

 ray are spaced in the median radial areas. The "primary apical" plates are 

 prominent in small and modium-sizcd specimens. 



Marginal plates in form not diflerent from the two preceding species. Plates 

 of the two series are obliquely opposite, but not alternate, the lower plate being 

 slightly farther distad than the upper. The intervening suture is oblique. Supero- 

 marginals, about fort}' in number, with a prominent boss on the upper rounded 

 margin bearing a single, tapering, bluntly pointed, thomy (almost hispid) surfaced 

 spine, proximally .5 or 6 mm. long; exceptionally two are present on one or two 

 plates; seven or eight small thorny spinelets are irregularly distributed over the 

 surface of the otherwise naked plates. The odd interradial superomarginal is 

 prominent, is elevated half its height above the level of the other superomarginals, 

 and bears a single upright spine 7 ram. long. 



Inferomarginals bear two spines (or sometimes only one) similar, and the 

 longer subequal, to those of upper series, except at base of ray where both spines 

 are typically club-shaped, with a broader tip than base. Farther along rav, 

 however, the spines taper. The lower of the two is the shorter. Ten or twelve 

 spinelets are scattered on surface of plate. The unpaired inferomarginal bears 

 one or two short club-shaped spines with sometimes one or two accessory club- 

 shaped spinules. Typically the proximal first, second, and sometimes third, or 

 first and thinl, or first only, vertical inferomarginal sutures have a pectinate pedi- 

 cellaria with three to six robust sharp converging spinelets to each comb. The 

 aberrant specimen noted above as having numerous pedicellaritB on the abactinal 

 surface of rays has the inter-inferomarginal pedicellariie extending far along rays. 



Adambulacral plates wider than long; tiie furrow series of consecutive plates 

 well spaced. jVrmature (1) a furrow series of four to six subequal slighth' curved 

 spinelets, the median two or tlirce about as long as plate, or the laterals markedly 

 shorter. (2) On the actinal surface are two strongh* club-shaped spines in a 

 transverse series, with sometimes proximally a third much smaller one at outer 

 end of the line. Far along ray the spines are not so obviously club-shaped, or 

 they may taper a trifle, but are blunt and stout at tip. One or two additional 

 spinelets stand on the adoral side of the plate. The form of the proximal actinal 

 adambulacral spines seems to be characteristic and holils in specimens from widely 

 separated localities. 



Mouth plates with marginal graduated series of five or si.x spines, the inner 

 and sometimes the next much enlarged; parallel to median suture is a linear series 

 of about six actinal club-shaped spines, which become slenderer as they proceed 

 outward. 



Actinal interradial areas small; much smaller than in the B. muiabUu^: six 

 to eight j)lates in each area, these e.xteniling to the second inferomarginal. Each 

 plate has a few unequal clavate sjiinelets, one usually larger then the rest. In the 

 aberrant specimen already referred to, each area has one to five pectinate pedicel- 

 lariie with three or four pointed spinelets in each comb. Another specimen has 



