ASTEBOIDEA Of NOKXU PACIFIC AND ADJACENT WATEBS — FlrillElt. 321 



two isolated ossicles in many of the meslies. Anus surrounded by four or live large 

 paxill^. As in preceding species a verj- narrow bare sulcus extends from inter- 

 radial angle about half way to center of disk. Papula- prominent, but usually not 

 quite so large as in preceding species, about three to ten to a mesli on disk, one to 

 three in distal half of ray where skeleton is closer. 



Marginal plates very prominent, spaced, in a single series, about twenty to 

 thirty on each side of a ray and confined to the margin. Superomarginals not 

 different from abactinal pa.xilla^ and indistinguishable from them as a rule. Infero- 

 marginals with fairly high pedicels (relatively about as m popposus), bearing two 

 vertical or transverse palmate series of six to nine stout tapering pointed skin- 

 covered spines, the mesial of which are the longest. Sometimes there Ls one main 

 series, ami two or three smaller spines stand adorally out of the series, or there may 

 be a second adoral series of less conspicuous spinules, but few m number. Spines 

 of proximal plates shorter than rest, except near tip of ray. The spines varv' in 

 length but arc about as long or a third longer than the extreme width of the to|) of 

 the pedicel and often twice as long as its height. The tlistance between the top of 

 two adjacent margmal plates is slightly less to one-tliird greater than the extreme 

 height of pedicel and longest spine. The prominent bristling spaced marginal 

 paxillae form one of the characteristic features of this species. 



Actinal intcrradial areas rather small, about thirty-five to forty plates to 

 each area. Plates obscureil by integument which has fine furrows or wrinkles 

 leading from interadambulacral sulcuses to marginal plates. Plates appear spaced, 

 each bearing one to four short stubby papilliform spinelets, very delicate when 

 dried. Plates arranged irregularly in rows, between the wrinkles. A series of 

 very small widely spaced actinal intermediate plates extenils over three-fourths 

 length of ray. They bear usually one or two stumpy spmelets, or are spineless. 



Adambulacral plates with (1) a palmate furrow scries of five or sLx (distally 

 three or four) slender tapering skin-covered spinelets (united for about half their 

 length by a web) of which the second or third mesial arc subequal, the laterals 

 much shorter. These spinelets are of about same length as in Ileterozonias alter- 

 natus and about as long as the base line of comb. On the jiroxiinal part of ray 

 in some specimens there are seven or eight spinelets to a furrow comb. (2) On 

 actinal surface is a transverse series of four (three on smaller examples, varying 

 to two and five) much longer, slender, terete, blunt, skin-covered spines, the second 

 or tliird usually longest (exceeding in length the width of plate), the outer about 

 one-half length of inner (where there are tliree spines); when two spuies only arc 

 present they are subequal and long. The longest spines are about twice tvs long 

 as the longest furrow spinelet. 



Mouth plates just a trifle narrower than in 77. alternatus. Free margin with 

 a webbed series of about eleven spinelets increasmg in length toward mner end of 

 each plate to two or three much enlarged spines, the mnermost stoutest. On 

 actinal surface of plate near inner end of each is a stout, though slender, spine. 

 Sometimes instead of this a small one stands on outer end of plates, or there may 

 be two or three small spines, or the surface may be entirely unarmed. The furrow 

 spinelets are usually eleven, but vary to nine or twelve even in otherwise tyi)ical 

 57444°— Bull. 7ti— 11 21 



