ASTEBOIDEA OF NORTH PACIFIC AXD ADJACENT WATERS — FISHER. 155 



a central and five radial areas. Adambulacral plates with eight or nine spinelets 

 terete, tapering and bhintly pointed, arranged with two on furrow margin, and on 

 actinal surface in about tluce longitudinal series, two s])inelets to eacii. Mouth 

 plates with a movable, recurved, conspicuous lanceolate spine common to the pair, 

 and a marginal series of five to eight spinelets graduated from center of series toward 

 either end. Actmal interradial areas large, with squarish plates in regular series 

 parallel to furrow, each plate bearuig a group of five to twelve radiating stout, short, 

 pointed spinelets. Superambulacral plates absent. Tube feet with well-developed 

 sucking disks. No pedicellaria;. 



Description. — Abactinal plates paxilliform on paj)ular areas (r[.v.); elsewhere 

 simply strongly convex or only slightly elevated and with flattisii top. Plates are 

 arranged in regular series parallel with the median radial which contains largest 

 plates with tiie exception of the conspicuous primary basals ami central plate. 

 Plates are also in regular rows parallel to interradial line, but inside of the pentagon 

 defined b}' the five basals the plates are not regularly arranged. Opposite first two 

 marginals are five rows of paxillfe. Tabulum of paxilla is so formed that summit 

 is narrower than base, the side sloping upward gradually. Tabulum on papular 

 areas, surmounted by a radiating group of fifteen to twenty-three (on radial row) 

 slender tapering spinelets which are longer than height of tabulum. The paxillae 

 decrease in size toward margin of area. Right in center of disk is a small isolated 

 papular area with pa.xilliform plates. The central j)late has twenty-seven spinelets. 

 About two rows of plates along interradial line and one or two rows connecting the 

 basal plates (thus forming a pentagon inclosing the central papular area) have 

 shorter spinelets than tiie rest. Tiie primary basal has thirty-five to forty spinelets 

 or elongate granules. 



There are five radial papular areas, separated by two or three rows of plates 

 along each interradius, and a central area isolated by or inclosed within a pentagon 

 the corners of which are the five basal plates. The sides of this jientagon are about 

 three plates thick, althougli there is no regular arrangement of plates. Papulte, six 

 about each plate, extend nearly to tip of ray, and are absent from margin opposite 

 first two or tliree marginals. Plates of papular areas slightly lobed, tlie lobes of 

 adjacent plates fitting togetlier end to end, but overlapping slightly upon radial 

 series, and always in central j)apular area where the plates are smaller and more 

 crowded. Elsewhere tlie plates are subcircular or very irregular, tiiree to five 

 sided. Here and there adjacent to papular areas are very small plates, probably 

 large plates in course of development. 



Marginal plates massive, the superomarginals forming a broad, raised, arched 

 border to abactinal area; last two or three plates in contact medially, though the 

 last pair of plates is usually separated by wedge-siiaped terminal plate. In type, 

 seventeen plates to side, or eiglit to ray; interradial slightly larger tlian others, 

 subtriangular superomarginals transversely oblong, wider tluin liigh, tumid, covered 

 with spaceil granuliform sjjinelets, which are thimble-shaped on rounded margin of 

 rav, and decrease in size and thickness toward inner edge of plate. A narniw bare 

 cliaiinel between consecutive plates, and a longitu<linal diannel on side of ray. 

 separat ing the two series. 



Inferomarginals correspond in number and position to superomarginals, but 

 are not so tumid. Granuliform si>inulation is coarser than on superomarginals, 



