ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 133 



Remarks. — This genus agrees with Benihopecten in liaving long rays and odd 

 interradial marginal ])lates. It difFers in possessing usually more extensive papular 

 areas, in ha\nng niueh more spiny marginals, and abactinal plates, which instead 

 of being flat and often immersed, are tabulate and paxiiliform, bearing numerous 

 spines of conspicuous length. 



Superficially the most striking feature of Nearcliasiei- is this dense armament 

 of abactinal s{)ines, sjiringing from low tabulate plates which in their essentials are 

 like those of Luidiaster dawsoni. The species show more outward resemblance 

 to Luidiaster than to Benihopecten in spite of the presence of one or more odd 

 interradial marginal plates. 



KEY TO THE SPECIES OF NEARCHASTER. 



a'. Abactinal acceii,sory epiiiules long and slender, forming with the primary spines a dense armament; 

 eecondary plates with long Bpinule.s; furrow spinules one to three; papulse extending to middle 



of ray aciculnsus, p. 133. 



a'. Abactinal ac<-es.«ory spinules not greatly developed in length or number; if developed at all only 



two or three around each spine; secondary plates with short spinelets; abactinal integument 



firmer and plates closer together; furrow spinules four to seven. 



(/'. Numerous abactinal pectinate pedicellariae together with inferomarginal and actinal intermediate 



pedicellaria;. Disk larger. Twenty adambulacral plates to ten inferomarginal.'^; papulae 



extending as far a.s twenty-eighth to thirty-fifth superomarginal pediccllaris, p. 138. 



6'. Very few abactinal pectinate pedicellaria; and only e.xceptionally actinal or inferomarginal ones. 

 Disk smaller. Twenty-two adambulacral plates to ten inferomarginals; papulae extending aa 

 far a^ ninth to twenty-third superomarginal variabilis, p. 137. 



NEARCHASTER ACICtJLOSUS (Fisher). 



PI. 24, fig. 1; pi. 26, figs. 1-3; pi. 55, figs. 1, la, 16; pi. .56, fig. 3; pi. 118, fig. 3. 



AcantharchasUr acimlosus Fisher, Zool. Anz., vol. 35, March 29, 1910, p. 550. 



Nearchaster aciculosus Fisher, Ann. and Mag. Nat. Hist., ser. 8, vol. 7, Jan., 1911, p. 92, figs. 1, 3, 5. 



Diagnosis. — Rays five (very rarely six). R = 146 mxn.; r=16 mm.; R = 9 r; 

 width of ray at base, 19 mm. Cotype: R = 217 mm.; r==16 mm.; R = 13.5 r; 

 width of ray at base, 19 mm. This is the longest-raj'ed specimen, station 48S1. 

 Rays very long, slender, flexible, and tapering gradually from narrow base to 

 attenuate extremity. Abactinal surface covered with stellate plates of two general 

 sizes, large primary plates bearing a raised tabuluni with a central, long, slender, 

 movable needle-like spine surrounded by a circle of eight to fifteen divergent, very 

 slender, seta-like spinules one-third to over one-half the length of spine; inter- 

 spersed among these, smaller plates with spinules only, or perhaps an incipient cen- 

 tral spme; beyond middle of ray, plates with a uniform covering of minute spinelets, 

 three or four to a plate; a few abactinal pectinate pedicellaria;. Papula? mmierous, 

 large, distributed all over disk and on ray to about two-thirds K from center. 

 Superomarginals with two or three long, slender, movable spines, surroiuuled by 

 seven to twelve auxiliary spinules; inferomarginals sunilarly armed; about three 

 or four (as few as one, or sometimes all five) interradii with an odd marginal plate, 

 bearing one or two spines, in both series, but not always correspondmg; an odd 

 superomarginal sometimes opposite paircil interradial inferomarginals. Ailambula- 

 cra! plates with two to four furrow s])inules, ami two or three long, slender actinal 

 ones in oblique series. Mouth plates broadly spade-shaped with nine to fifteen 

 marginal spinules, subequal except for the inner one or two, which are enlarged to 



