i8o DISCOVERY REPORTS 



abactinal paxillar spinelets are shorter and stouter, somewhat clavate in general contour, 

 with the rather numerous thornlets at the tip, and usually only a slight distance below 

 the tip. In regiilaris the spinelets are usually slender, somewhat tapered in general 

 contour with far fewer terminal spinelets and other prominent thorns occurring irregu- 

 larly on the side of shaft half-way to the base (but not in all spinelets). These are not 

 invariable characters but rather the habit of the two forms. 



I think it will be convenient to maintain subarcuatus as the antarctic representative of 

 regiilaris; but as I have indicated in the synonymy there seems to be no place for O. 

 octoradiatns. 



Type locality. Challenger St. 150. Between Kerguelen and Heard Islands, 

 52° 4' S, 71° 22' E, 150 fathoms, coarse gravel, bottom temperature 35-2° F. 



Distribution. Probably circumpolar. Between 80° and 88° W, yo^-yi" 18' S, 

 450-500 m. (' Belgica ') ; Coulman Island, 73° 30' S, 170° E, 100 fathoms; South 

 Shetland Islands, 242 m. ('Discovery'). 



Genus Crossaster Miiller & Troschel 

 Crossaster Muller and Troschel, Monatsber. preuss. Akad. Wiss., 1840, p. 103. Type Asterias papposa 

 Linnaeus. 



Crossaster penicillatus Sladen 

 Crossaster penicillatus Sladen, 1889, p. 446, pi. 60, fig. 5; pi. 62, figs. 9, 10.— Koehler, 1908, p. 560 

 (Gough I.).— Bell, 1905, p. 249.— Clark, 1923, p. 295.— Mortensen, 1933, p. 272. 

 St. H. Cape Trawler, 34° 4' S, 17° 36' E, 272-402 m., i specimen. 



The specimen has 10 rays; R 65 mm., r 20 mm., br 11-14 mm. Clark's specimens 

 had from 8 to 10 rays— the young 8 or 9, and the adults (R 55-60 mm.) 9 or 10 rays. 

 The furrow spines are long and slender, basally webbed, 5 at the base of ray, then 4, 3, 

 2, and finally i near the end. This single spine is co-ordinated with the curved transverse 

 comb so that the adambulacral armature consists of essentially a single transverse series, 

 which, so far as the 3 innermost spines are concerned, descends somewhat upon the 

 furrow face of the plate. The subambulacral spines are long, slender, tapered and 

 pointed. The combs are transverse or obliquely transverse, curved, with the convexity 

 adoral. The first few combs consist of about 5 basally webbed spines, rapidly increasing 

 to 7 and 8 ; then to 7, 6, 5 on outer fourth of ray. The spines stand on a curved con- 

 vexity or crest of the plate, which becomes more prominent on the outer part of ray. 

 Each mouth-plate has 10 furrow spines, the inner 3 or 4 conspicuously longer than the 

 others, and about 10 long subambulacral spines. Abactinal spinelets are numerous, 

 long, very delicate. It will be seen from the above that the spines are not much more 

 numerous than in Sladen's type, in which R is 34-36 mm. 



Type locality. Challenger St. 135c, off Nightingale Island, Tristan da Cunha, 

 no fathoms. 



Distribution. Tristan da Cunha and Gough Islands, South Africa; Marion Island; 

 80-800 m., sand, mud. The range is therefore in the sector between 40^ £-15° W and 

 33°-47° S. 



