ASTEROIDEA OF NORTH PACIFIC AND .VDJACENX WATERS FISHER. 97 



extends very slightly fartlicr along ray than in cither of the two preceding forms. 

 Actinal jtlatos bear a low carination (of narrow ellij)ti(al fomi) crowned with small 

 pa]iillif()rm spinelets, those in center being clavately thickened and fifteen to thirty 

 in nuinbcr, the peripheral, about twenty or less according to size of ])late, being 

 slenderer. 



Madreporic body about midway between extreme margin and center of disk, 

 11 mm. in diameter, and hidden by about twenty-five large pa.xilhr. 



Anal aperture of conspicuous size, though hidden by jjaxilhc; tube feet large, 

 pointed, without calcareous grains or rods in walls. 



Type.— Cut. No. 24672, U.S.N.M. 



Type-locality. — Albatross station 3340, south of Alaska Peninsula, between 

 Unalaska and Kadiak (lat. 5.5° 26' N.; long. 155° 2G' W.), 695 fathoms, mud; one 

 specimen. 



Distribution. — Known only from the type-locality. 



RemarJcs. — This species differs from both of the foregoing forms in the following 

 characters: Form of abactinal plates; width, covering, and special armature of 

 marginals; armature of adambulacrals. From D. eximius it further differs in the 

 size and character of abactinal paxillfr; shape of rays; in distribution of papulas 

 along mid-radial line; in having narrower superomarginals; form of outer end of 

 inferomarginals due to different armature; in having narrower actinal intermediate 

 areas on rays; and a different armature, as well as less prominent carinations to 

 actinal intermediate plates. From D. borealls the present sjiecies further differs 

 in having slightly narrower rays (probably not constant); larger paxilhv in center 

 of disk; in armature of actinal intermediate plates wliich have less prominent cari- 

 nations; in armature of mouth plates. D. Isetmopfiilus differs from nesiotes, of the 

 Hawaiian Islands, in having much broader rays; longer paxillse pedicels in pro- 

 portion to width of crown of spinelets; more distantly spaced abactinal plates; 

 marginals wliich correspon<l plate for plate and do not alternate on outer part of 

 ray; wider superomarginals and inferomarginals, especiallv the latter; a less plane 

 actinal surface to inferomarginals; less thick specialized ridge; broader fasciolar 

 grooves; more prominently carinated actinal intermediate plates; larger actinal 

 intermediate areas on rays. The armature of adambulacrals and mouth plates is 

 very similar in the two forms, as well as the finer spinulation of marginals and 

 absence of special superomarginui spines or tubercles. 



DIPSACASTER ANOPLUS Fisher. 

 PI. 16, figs. 1, 2; pi. 52, figa. 4, 4a, 

 Dipsacaster anoplus Fisher, ZooI. Anz., vol. 35, March 29, 1910, p. 547. 



Diagnosis. — Rays five. R=25mm.; r = 12.5 mm.; R = 2 r. Breadth of ray 

 at base, 13 mm. General appearance greatly resembUng a species of Leptijchaster" 

 (as L. pacificus or L. anomalus). Rays tapering more or less gradually to a 

 bluntly pointed extremity; sometimes slightly swollen on outer part; interbra- 

 chial angles wide. Abactinal paxillar area fairly compact; paxilla? arrau'^ed in 



" See Remarks oa p. 100. 

 57444°— Bull. 76—11 7 



