ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHElt. 267 



KEY TO NORTH PACIFIC FOHMS OK UENRICIA." 



a'. One furrow spinelet, except sometimes on the ilLstal portion of ray, whorf two may bi- prtwonl on the 

 furrow face of the adambulacrals. 

 6'. All the psemlopaxilloe or groups of ppinelels small, rather close set, the aboctinal skeleton not funn- 

 ing an open mesh work; pseudopaxillie with comparatively few (one to fifteen) short spinclets; 

 papuliE few (one to three, less often four or five) to an area. 6 

 f'. Raya moderately long and slender; marginal plates typically inconspicuous, and not normally 

 forming regular series as in cschrichtii (but in some varieliea marginal plateti are present, when 



R is considerably greater than 3r and size is frequently larger) sanguinolenla, p. 271. 



c'. Rays short, stout, and often very tumid; marginal plates with few spinelet^, forming regular 



series achrichlii, p. 276. 



6-'. Abactinal pseudopaxilla moderately to very large, close-set, with numerous small delicate, some- 

 times granuliform spinclets; papular areas small, typically smaller than the pscudopaxillte; 

 marginal and actinal intermediate plates forming three very regular, conspicuous, usually 

 juxtaposed series, 

 f'. Abactinal pseudopaxillae typically with small granuliform or clavate spinelets; adambulacral 

 spineleta few in about two transverse series. Typically one spinelet in furrow except at very 

 tip of ray where two may be present . 

 (/'. Papular areas smaller than adjacent pseudopaxillae which have usually more than twenty 

 spinelets; marginal plates squarish, large, not much wider than long, not separated by 

 prominent transverse grooves (as wide as the elevated ridge of plate); actinal intermediate 



series reaching quite or nearly to ti]) of ray leviuscula, p. 280. 



d-. Papular areas usually larger than pseudopaxillse, much sunken, the latter elongated with 

 fewer than twenty spinelets arranged on the tabulate elevation in two or three rows; 

 marginal plates much compressed, the thin spine-bearing tabula separated by fairly 

 deep grooves; actinal intermediate plates not distinguishable much beyond middle of 



ray anTuctens, p. 291. 



f-. Abactinal pseudopaxUlae with numerous slender often glassy spinelets ending in three to several 

 long sharp awns or points; adainbulacral spinelets numerous (twenty-five to fifty); typically 

 with two spinelets in furrow beyond middle of ray but only one proximally; actinal inter- 

 mediate plates extending one-half to three-fourths length of ray mullispina, p. 286. 



b^. Abactinal skeleton more open, with large often sunken papular areas containing numerous papuUe. 



c'. Spinelets scattered along the ridges surrounding papular areas, often quite small; not in 



definite clusters or pseudopaxillas; adambulaeral spinelets in a single, sometimes zigzqg, 



transverse series. 



<p. Rays slender, long, and rigid, the skeleton forming an open mesh work with large sunken 



papular areas; abactinal spinelets minute, generally immersed in the integument and 



arranged along the trabecular ridges in one to three irregular series; adambulaeral spinelets 



in zigzag transverse series, few, thick, stubby, and immersed in membrane; marginals 



regular with large intermarginal papular spaces asfxra, p. 293. 



cP. Ruys weak; spinelets comparatively largo (as long as theheightof ridge bearing them) well 

 spaced, in a single scries along the skeletal ridges. Adambulaeral spinelets slender, 

 long, in a transverse series, webbed basally, but not impeded by a thick investment. 

 Marginals not always regular aathenactit, p. 297. 



aOwing to the variability of the species of this genua identification by a key is unreliable. The 

 accompanying "attempt " will serve to place a specimen near its proper place in the system when recoureo 

 must be had to the figures and descriptions. There is a small percentiige of specimens that are very 

 ditficult to classify even with ample material for comparison; surh are usually inlergrados, " friiits, " or 

 hybrids. 



^Kor California speiiiueus which seem lo belong here, see al*i //. Ifiiiiaeiilii tiimcriln and yoimg or 

 dwarfed leviuscula. 



