ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER 47 



are to be found on the abactinal surface. All the plates of the ray bear a prominent 

 central or subccntral, stout, tapered spine, about 2 to 2.5 mm. long on the carinal 

 plates, a little less on theadradial, 2 to 2.5 mm. on the superomarginal, about 3.5 mm. 

 on the inferomarginal, and 5 to 6.5 mm. on the actinolateral plates. The carinal spines 

 are generally blunt, and an accessory spinule is sometimes present. The adradial 

 and marginal spines are a little sharper, while the actinolateral spines are quite sharp 

 and acicular. The general surface of the abactinal plates is beset with scattered small 

 granules and granuliform spinelets (invisible until specimen is dried) but on the supero- 

 marginal plates spinelets begin to appear, which increase in number and in length 

 toward the furrow, attaining a length of 2 mm. on the actinolateral plates. They 

 are very slender, terete, and delicate. The whole surface of the plates, granules, 

 spines, and spinelets is covered and incased by a fleshy rather jellylike membrane 

 which is decidedly slimy in life. Especially on the spinelets is the sheath conspicuous. 

 Each spinelet has a thick clavate, saccular sheath with a rounded tip, entirely obscur- 

 ing the slender spinelet within. On account of the size of this pulpy sheath the 

 actinolateral spinelets appear to be closely crowded. The primary spines are also 

 similarly invested but the sheath is not proportionally so thick; they appear heavy, 

 and on the actinolateral plates, flattened. This membrane shrinks rapidly with 

 drying and in dried specimens almost disappears abactinally. 



Fair-sized pedicellariae (1.5 to 1.75 mm. long) are numerous on the abactinal 

 surface, but decrease greatly in numbers on the actinolateral plates. They are found 

 on the borders of the papular areas, usually at least one, sometimes two or three to 

 an area. 



Papulae numerous, vermiform, large, usually longer than the spines. There are 

 four or five, proximally in each of the abactinal areas (four series), finally diminishing 

 in number to one on outer part of ray. On the sides of the ray, in the four series, 

 there are one or two papulae. Distally there are but three lateral series of papulae, 

 then two, then one and finally at the tip, none. 



The terminal plate is very prominent, cordate, with a deep sulcus on the proxi- 

 mal side, and it is broader than the terminal, attenuate portion of the ray immedi- 

 ately adjacent to it. It measures 4.5 mm. to 5.5 mm. long by 3.5 mm. to 4 mm. 

 broad in fully grown specimens. 



The prominent adambulacral plates have a conspicuous furrow keel. Their 

 armature is as follows: (1) On the tip of the furrow projection is a short terete spine, 

 often curved a little furrowwards at the end, which bears a large pedicellaria (2 mm.), 

 with curved jaws, and two or three smaller companions. The latter are sometimes 

 absent. (2) Following this is a transverse series of three or four slightly curved, 

 tapered pointed spines, which diminish in size as they proceed outward. The inner 

 two are subequal, 2.5 to 3 mm. long, tapered and pointed; the outer two are about the 

 size of the spinelets of the adjacent plates. Adorad to them is a transverse series of 

 two similar spinelets. The alternating nonprominent plates have a small spinelet on 

 the margin bearing a pedicellaria or sometimes two or three, and on the actinal sur- 

 face four spines in two transverse series, about equal to the smaller spines of the prom- 

 inent plates. The actinal spines and spinelets are sheathed by the characteristic 

 pulpy membrane which, owing to pressure, may form a rather prominent flange along 

 either side of the spine which takes on a blunt, lanceolate, squamiform appearance. 



