ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 95 



surrounding them; in covering of marginal plates; in having thicker specialized 

 ridges to inferomarginals, \vith correspondingly narrow fasciolar furrows; in the 

 special spines on both scries of marginals; in having differently shaped adambu- 

 lacral furrow spines; and in having mudi smaller actinal intermediate areas on rays, 

 as well as a different armature to the intermediate ])lates. Still other differences 

 have been alluded to in the course of the description. 



A fairly well-marked variety, or perhaps representative species, is found in Japan- 

 ese waters. The principal external differences are the following: The Jaj)anese 

 form has the paxillse still smaller on middle of disk, a larger madreporic body (pos- 

 sibly not constant), smaller and less compact granules on superomarginal plates; 

 tliinner specialized ridges to inferomarginals (more as in eximius) with, wider 

 fasciolar grooves. The furrow spines arc nearly as in horealis, but there is frequently 

 an additional s{)ine. Thus the number is usually sLx or seven, and occasionally 

 eight. The most important difference is in the abactinal plates, so far as my 

 limited examination can determine. In the Japanese form the plates of ray are 

 also lobed, but the median radials or carinals are not so closely placed as in horealis. 

 They are also frequently decidedly lobed. The plates along the course of the 

 muscle bands are not modified. The lobing is apparently more distinct in medium- 

 sized than in very large specimens of Dipsacaster. 



DIPSACASTER LiETMOPHILUS Fisher. 



PI. 12, fig. 3; pi. 15, figs. 1, 2; pi. 52, figs.'S, 3a, 36; pi. 53, fig. 2. 

 Dipsacaster lalmophilus Fisher, Zool. Anz., vol. 35, March 29, 1910, p. 547. 



Diagnosis. — Rays five.* R=118mm. ; r = 45mm.; R = 2.6r. Breadth of ray at 

 base 47 to 52 mm. Rays tapering gradually to a bluntly pointed extermity ; general 

 form flattened; interbrachial arcs wide; paxillaj regularly arranged as in preceding 

 species, and similar; slightly larger ui center of disk than elsewhere. Abactinal 

 plate not lobed, except rarely on median radial area; papuliE generally distributed, in 

 sixes about each plate. Marginal plates massive; superomarginals nearh' quadrate 

 beyond proximal fourth of ray, covered ^\^tll close-set delicate spinelets like those 

 of paxilUe and without specialized spines or tubercles; inferomarginals narrower 

 than in preceding two species, covered with delicate imbricating narrow squamiform 

 spinelets which become enlarged into five to seven small tapering spines on outer 

 aboral end of plate, causing a decidedly serrate appearance to edge of ray; fasciolar 

 furrows rather wide. Adambulacral furrow spines seven very strongly compressed 

 and blade like, their edges to furrow; tip much broader than base, rounded and 

 thm like a knife; on actinal surface ten to eighteen slender tapering or davate 

 spinelets, decreasing in size outward. Actinal intermediate plates extending far 

 along raj'; intermediate areas about as extensive as in horealis, but a single row of 

 plates extending 0.9 length of ray measured from interradial angle. 



Description. — Rays are narrower than in either of the two preceding species, 

 but broader than in D. nesiotes Fisher. Paxilla; regularly arranged along sides of 

 area, slightly larger in middle of disk than elsewhere (except on mailreporic plate); 

 along mid-radial area not markedly larger than along either side contiguous to this 

 area. Paxillse very similar to those of D. horealis, the numerous spinelets (eighty 



