298 BULLETIN OF THE BUREAU OF FISHERIES. 



series; near center of each plate a robust tapering spine (or occasionally 2) much longer than the 

 plate (7 or 8 mm. I and directly obliquely upward and outward, these spines longest at about middle 

 third of ray and decreasing in length very gradually toward its extremity, most of them very curiously 

 bifid for half or two-thirds their length, as if composed of 2 fused spines, and possessing, consequently, 



2 closely appressed points; abactinal margin of plate hearing 1 or 2 upright, much shorter spinules ( 2 

 to 3.5 mm.), robust, tapering and pointed, 1 often shorter than the other; general surface of the plate 

 bristling with small, spaced, capillary thornlets, very much smaller than the paxillar spinelets. 



Inferomarginal plates corresponding in number to superoniarginals, to which they are opposite, 

 forming a steep, slightly arched level to actinal area; they are also tumid, especially along the trans- 

 verse axis the tumidity passing into the upper plate without any conspicuous break at the suture 

 between the two. A few of the proximal plates with a transverse series of 3 stout, tapering, pointed 

 spines, frequently a trifle flattened and bifid like those of upper series; the rest of the plates, including 

 the ti est 2, bearing 2 such spines, the upper the longer (8 to 9 mm. ); toward distal part of ray the 

 lower occasionally much reduced in size, and on some of the plates the upper split to the base, being 

 in reality 2 spines with a common articulating boss; these spines are all commonly appressed to the 

 ray, as in Psila&ter. General surface of plates bristling with delicate spaced spinelets, which increase 

 in size toward lower end of plate. 



Adambulacral plates set obliquely; as a rule broader than long, with a curved furrow margin; 

 armature consisting of ( 1 ) a furrow series of 5 or, less commonly, 6 (in smaller specimens, 3 or 4), 

 compressed, rather delicate, slightly curved, blunt spinelets (4 mm.) often capped with a knobbj 

 membraneous tip, arranged palmately, and usually graduated in length from the adoral to the aboral 

 end of the series, these spinelets usually radiating stiffly apart; (2) on actinal surface an enlarged, 

 flattened, blunt spinule, frequently with a shallow groove running from tip halfway to base, this 

 surrounded by a variable number of smaller, flattened, blunt, membrane-invested spinelets frequently 

 arranged in 2 longitudinal rows, 3 or 4 in each, the spinule standing on the inner series or between 

 the 2, in which case the spinelets appear to form a wide circle around it; outer spinelets usually much 

 flattened at tip and furrowed lengthwise as if incipiently bifid; in smaller specimens there are but 2 or 



3 actinal spinelets and 1 spinule. 



Mouth plates elongate, narrow, prominent actinally; interradial length 13 mm.; width of combined 

 plates 5 mm. ; at inner angle of the 2 combined plates 2 stout, enlarged, somewhat curved blunt spines, 

 and the whole surface of the plate covered with thick, blunt, short, very robust spinelets which are 

 largest near the inner angle and decrease in size and thickness toward the margin adjacent to first 

 adambulacral; furrow series very angular and consisting of a group of spinelets, about 5 in number, 

 situated at a higher level than the tooth, and continued to the lirst adambulacral along the excavated, 

 short, free margin in 4 more short pointed spinelets. In a smaller specimen there is a regular and 

 prominent scries along the margin of the median suture, with a few slenderer spinelets along the 

 sides, lower down, the actinal surface being very prominent. The lirst adambulacral forms a short 

 and very wide companion plate. 



Actinal interradial areas small; intermediate plates small, extending in a single series to within a 

 short distance of tip; in interradial areas plates arranged in short irregular series extending fr adam- 

 bulacral to marginal plates; irregularly roundish, armed with a group of appressed, rather delicate, 

 often flattened, obtuse, grooved, occasionally bifid spinelets. similar near the adambulacral plates to 

 their outer actinal spinelets and forming thence all the transition between these and the lower spinelets 

 of the infcromarginals; these spinelets all sheathed in membrane, which is frequently swollen at the 

 tip. They frequently stand upright; spinulation by no means dense. 



Madreporic body large (7 nun. in diameter), circular to irregularly oval, free, situated nearer 

 margin than midway to center; striations rather fine; ridges narrow, branched, centrifugal. 



Color in life, madder brown. 



Locality: Station 43S0, off Los Coronados Islands, southwest of San Diego, Cal., 530 to 638 fins., 

 gray sand and rocks. 



