358 BULIvETIN 76, UiSITED STATES NATIONAL MUSEUM. 



PTERASTER PtTLVILLUS Sars. 



PI. 102. figs. 2. 4. 



Pteraster puhillus M. Sars, Oversigt af Norges Echinodermer, 1861, p. 62, pi. 6, fig. 14-18; pi. 7; 

 pi. 8; pi. 9, fig. 1-6. — LuDwio, Fauna Arctira, vol. 1, 1900, p. 470 (here in given an exten- 

 sive list of references, referring to Atlantic and Arctic localities, but not to the region of this 

 report, where the species has not heretofore been taken). — Fisher, Ann. and Mag. Nat. Hist., 

 ser. 8, vol. 5, Feb., 1910, p. 168. 



Two specimens from the vicinity of Bering Island are referred with some 

 hesitation to this species. They have the following characters: 



Diagnosis. — Rays five. R = 21 mm.; r=16.5 mm.; R = 1.27 r. Form nearly 

 pentagonal with breadth of ray at base about equalling minor radius; disk convex, 

 unil'orinly roughened by pronunent tips of paxillar spines; pseudopaxillae with 

 high pedicel and six, seven, or eight slightly shorter diverging spinelets, the tips of 

 which are connected in the supradorsal membrane by rather faint muscle bands, 

 about six radiating from central spine of each paxilla, the meshes thus formed con- 

 taining one to three papular pores. No spicides in membrane. Osculum small, 

 ambulacra narrow, feet in two rows. Adambulacral spines six proximally, then 

 five, then four distally, the innermost much the shortest, the next to outermost 

 longest; membrane emarginate between tips of spines, aperture papilla rather 

 narrow and free along aboral convex border. Marginal mouth spines seven (six 

 in a smaller specimen), slentler, tapering, the inner very short; all fourteen united 

 by a common web to tips; suboral spine a trifle longer than inner oral spine (which 

 is longer than interradial diameter of plates) slender, glassy, sharp, encased in a 

 pulpy sheath which makes it appear fairly robust. Actinolateral membrane 

 narrow, about the fourth spine longest whence the rest gradually decrease in length 

 to tip of ray, free edge of membrane narrow and slightly emarginate between tips 

 of spines. 



Color in alcohol dull yellowish gray or light yellowish brown. 



Type-locality. — Three miles north of Bergen, Norway, 50 to 60 fathoms. 



Distrihution. — Ludwig (Arktische Seesterne, p. 471) summarizes the distribution 

 as follows: Maine to Newfoundland (lat. 42° to 48° N.); on the Norwegian coast 

 from lat. 60° N. to Finmark; Barents Sea; Murman coast; Matotschkin Strait and 

 Kara Sea; Spitzbergen (to lat. 79° N.). To this must be added Bering Sea. 



Specimens examined. — Two, from station 4792, near Bering Island, 72 fathoms, 

 pebbles. 



Remarks. — These two specimens do not seem to be typical, although I have 

 had only the Latin diagnosis of Sars and a copy of figs. 2 and 9, pi. 7, and fig. 2, pi. 

 9, as a basis for comparison. According to Doctor Clark's key these examples 

 would be pulviUus. 



The differences seem to be as follows: fewer paxillar spinelets (eight to fifteen 

 in the type), a weaker reticulation (according to Sars' pi. 7, fig. 2 the bands are 

 cjuite heavy and the meshes contain one spiracle); more spiracula; the supradorsal 

 membrane has not a number of humps due to more prominent paxillte as shown by 

 Sars' figure, but instead the surface is roughened all over by the prominent spines; 

 the adambulacral spines are six only at the base of furrow near mouth plates; the 



