ASTEKOIDEA OF NORTH PACIFIC AND ADJACENT WATERS FISHER. 43 



6'. InferomarginaU more transversely placed, and lesa numerous; specialized ridge of each plate about 

 as wide as adjacent furrow. Superomarginals, broader and not paxilliform; quadrate in shape. 



propinquus, p. 54. 

 a?. Superomanjinals larger, forming a conspicuous margin to abactinal area and wider and shorter in 

 intorradial angle than at middle of ray. 

 6'. Stellate with sharp rays; abactinal plates decidedly stellate or lobed on papular areas; R.=2.3 to 

 3.1 r; inferomarginals (with spinelets) more than twice as wide as long; marginal plates twenty- 

 two to thirty-five in adult specimens pacificus, p. 45. 



6-. Stellato-pentagonal, or stellate with short blunt rays; abactinal plates only ob.scurely lobed or stel- 

 late on papular areas; R. = l.() to 2 r; inferomarginals on ray twice or lesa than twice as wide a.s 

 long; marginal plates ten to oightcon in adults avomabis, p. 48. 



LEPTYCHASTER ARCTICUS (Sars). 

 PI. 8, fig. 1; pi. 9, fig. 4. 



Astropeclen arctinu M. Sars, Reise i Lofoten og Finmarken, Nyt Mag. f. Naturvidensk., vol. 6, 



1851, p. 161; Fauna I.itt. Norvegia;, 1856, Heft. 2, p. 61, pi. 9, figs. 16-18; Oversigt af 



Norges Echinodermer, 1861, p. 32. 

 Astropeclen liUkeni Barrett, Ann. and Mag. Nat. Hist., vol. 20, 1857, p. 45, pi. 4, figs. 3a, 6, c. 

 Astropeclen arcticus and liitkeni Dujardin and Hdte, Hist. nat. zoophjrtes Echinodermes, 1862, 



p. 428. 

 Archaster arcticus Verrill, Amer. Journ. Sci. and Arts, ser. 3, vol. 16, 1878, p. 214. — Storm, K. 



Vidensk. Selskabs Skrifter, Throndhjem, vol. 8, 1878, p. 252. — Pehrier, Nouv. archives 

 du mus. d'hist. nat., ser. 2, vol. 1, 1878, pp. 32, 88. 

 Leploplychasler arcticus Sladen, Challenger Asteroidea, 1889, p. 189. — LtJDWiG, Fauna Arctica, 



vol. 1, 1900, p. 452. 



Diagnosis." — Rays five. R = .3'2mm. ; r=10 mm.; R = .3.2 r. Breadth of ray 

 at base, 12 mm. (measured from interradial line). Disk medium-sized, rays taper- 

 ing gradually to a blunt extremity; interbrachial areas rounded but rather abrupt; 

 abactinal surface slightly inflated ; sides of ray rounded ; superomarginal plates small, 

 resembling enlarged paxilloe, not markedly wider at base of ray than at middle 

 or on outer third, forming a narrow margin to abactinal area; inferomarginals short, 

 but fairly wide, placed very obliquely and forming the rounded edge to ray, most of 

 the series being visible from above; no specialized spines on either series; adam- 

 bulacral plates with a furrow series of three or four spinelets, and on actinal surface 

 two or tliree longitudinal series (often irregular) of three to five spinelets eacli, with 

 sometimes two or three small spinelets out of line; abactinal paxillae very compactly 

 placed, longest on interradial area of disk and on either side of median radial area 

 along ray; actinal interradial areas fairly large, the intermediate })lates extending 

 far along the ray. 



Description. — The paxillas are closel}' placed and the difference in size between 

 those of the midradial region of ray and center of disk, and those along side of paxillar 

 area (i)articularly in the interradial region) is very marked — much more so tliaii in 

 Lepty chaster pacificus. A large paxilla of tlie interradial region of disk presents 

 a slightly convex crown of small terete, compactly placed spinelets, varying in 

 number according to the size of the paxilla, a fairly large one liaving twenty to 

 twenty-five peripheral and about the same number of central sj)inelets, a trifle 

 shorter than column of paxilla. Papula; absent from center of disk and along median 



" From specimen taken at station 4792, in the vicinity of the Commander Islands. 



