ASTEUOIDEA OF NORTH PACIIIC AND .ADJACENT WATERS — FISHER. 235 



marginals, twelve to seventeen in number from interradial lino to extremity of ray, 

 confined entirely to side of body, and rather inconspicuous; very irregular as to 

 shape; successive plates frequently separated l)y small intermediato encroaclung 

 abactinal plates, each plate with a tapering blunt spine artictdated rigidly to a cen- 

 tral boss and a marginal series of rugose granules, there being also one or two 

 smooth subconical granules on the general surface, occasionally, also, a pedicel- 

 laria just beneath the spine. Inferomarginals very similar to superomarginals, of 

 the same number, but not opposite to them; similarly armed; but the pedicellariie 

 very rare, actinal uitcrmediate plates encroaclung anil separating most of the 

 proximal inferomarginals. The marguial plates are very characteristic, in this spe- 

 cies, being remarkably small m most specimens and usually more or less irregular 

 in shape and disposition. In many cases the actinal and abactinal plate's are inter- 

 calated between a few or many of the marginals. In one extreme case (station 

 3344) several superomarginals are separated by two abactinal plates hi longitudmal 

 series, so that normal superomarginals seem to alternate with two verj' much 

 smaller ones. In young specimens this encroachment does not take place. A 

 curious variation is prcsentetl by a specimen (wliich is other\vise not typical) from 

 station 4530, where there are several mtermarginal jdates on each ray. These are 

 simply abactmal plates, around wliich the marginal plates have grown, inclosing 

 and segregatmg them, as it were. Exceptionally, the marginal plates bear two or 

 even three spines. One spine is more usual, however, and in a specimen with 

 R = 113 mm., is 4 to 5 mm. long, measured from the general level of the plate. In 

 lai^e specimens pedicellaria^ are rare on the marginals. 



Adambulacral armature, consisting of (1) a smgle blunt spme, usually consid- 

 erably compressed and somewhat tapering, situated on the angular furrow margin, 

 with occasionally a shorter similar adoral companion; or, one or two very short 

 spinelets or compressed granules on either side of the single spine; (2) on the actinal 

 surface a more robust, upright, tapering, blunt spme, situated just external to the 

 furrow spine, and just adoral to tliis there is frequently a medium-sized petiicellaria, 

 one jaw of which is broad serrate and rather deeply scoop-shaped, closing over the 

 other, wluch is smaller, thicker, and not hollowed out; margins of plates bordered 

 by numerous peculiar rugose granules, the general surface of the plate bemg covered 

 with the same. There is some variation m the thickness of the spines. In a large 

 specimen from station 3344 these are swollen anil blunt, and between the furrow 

 and actmal spine there is usually a large bivalvod pedicellaria considerably lower 

 and broader than in the type. 



Actinal intermediate areas large, paved witii unequal irregularly roundish, 

 polygonal, or elliptical plates, two series of which extend three-fourths the length 

 of ray, and a single series nearly to tip. Most of the plates bear a central high 

 pedicellaria of a peculiar shape, so far as this genus is concerned; jaws rather tluu 

 and wide at base, abruptly narrowing into the distal portion, which bends toward 

 the other jaw, and has a truncate serrated edge. This base varies in width, but is 

 commoidy one-half to three-fourtlis as wide as the plate. The pedicellariai are 

 wider than high to sliglitly higher than wide. Plates are bordered with a series of 

 rugose or denticulate granules, with several of the same size on general surface, 

 where there are, besides these, a number of considerably larger, smoother, subcon- 



