ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 135 



spinulcs, a few of whicli are often considerably longer than the rest, especially near 

 the base of raJ^ There may be no odd interradial inferomarcrinals, or from one to 

 four. In the cotype there are two, and one in the process of becoming "odd;" 

 in the type only one. An odd interradial superomarginal may have paired infero- 

 marginals, corresponding to it, and vice versa. The otld or interradial unpaired 

 marginal is a verj- variable character in this species, specimens from the same station 

 differing widely. Age seems to have something to do with its presence, and northern 

 specimens are more constant in having the maximum number. Typical examples 

 of this species lack marginal pedicellariae. 



Adambulacral plates wider than long, with slightly angular furrow margin. 

 Armature a pahnate furrow series of two, three, or four slender, unequal, spinulcs, 

 of variable length, and on the actinal sui-face of plate near the inner edge, an oblique 

 series of two, varying to three, long, slender spines. The figures will give a better 

 idea than description. The inner actinal spine (especially when tliree are present) 

 sometunes stands on the furrow margin and seems to form part of the furrow series, 

 the spine being then very disproportionate in size. In northern examples (Wash- 

 ington coast) only one furrow spinule is frequently present. A few minute thornlets 

 stand here and there about the large spines ; otherwise the surface of the plates is bare. 



Combined mouth plates broatily spade-shaped with a semicircular iimer naargin, 

 and a convex actinal surface. Each plate bears a furrow comb of nine to thirteen, 

 rarely fifteen, untapered, blunt spinelets of nearly equal length, except the inner- 

 most one or two, which are considerably enlarged. On the exposed surface of each 

 plate three to six spaced, long, slender, sometimes flat-ti])ped, spines form an angu- 

 lar scries. 



Actinal intermediate plates few, confined to interradial region, and armed 

 with one or two slender spines Oike those of adambulacral plates), with a few 

 accompanying spinules, or with only a very few spinulcs, or witli minute spinelets 

 simply. Northern spe<'imens may occasionally have a small pectinate pedicellaria 

 in one or two of the interradii. This is t_y]iically absent. 



Madreporic body convex, subcircular, situated less than half its own diameter 

 from nuirgin. Ridges irregularly radiating, branched; stria? interrupted. 



Color in alcohol, wliitish. 



Anatomical nofes.— No superambulacral plates. Gonads confined to inter- 

 radial regions and opening close to first superomarginal plate. Anus small; intes- 

 tinal coecum similar to that of Luidiaster dawsoni, a sac with four radiating 

 obtuse lobes, opening into stomacli, inconspicuous, though fair-sized; no distinc- 

 tion between dorsal and ventral stomachs; hepatic cceca extending into rays about 

 two or three r. Double ampulhe; tube feet large, in two rows, with sucking disk; 

 one Polian vesicle in each interradius except that of madreporic canal. No calca- 

 reous particles in tube feet, ampullsr, walls of stomach, or gonad. Dorsolateral 

 muscles weak, forming two inconspicuous bands on outer part of ray. 



Variations. — The principal variations have already been noted in the foregoing 

 description. The rays increase considerably in lengtli with age. Generally speak- 

 ing, the spinulation is more developed in southern than in iiorthem specimens, 

 especially the secondary abactinal spinules. Northern specimens have, as a rule, 

 more of the interradii, with an odd upper and under marginal plate, the full com- 

 plement being common; southern examples have usually two to four, .seldom five. 



