364 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



thirk, without reticulation superficially, without spicules, and with very numerous 

 spiracula; sides of rays rounded; paxillae stout with six to eight peripheral spines, 

 one being considerably enlarged, and from four to eight slenderer central ones; 

 peripheral spines give supradorsal membrane a bristling appearance; pedicel slightly 

 higher than shorter spines; adambulacral spines four to seven, the innermost short- 

 est, the others subcqual, flattened, truncate, bound together by a very thick skin 

 which is continued across actinolateral membrane as a low fold; actinolateral 

 membrane thick, wide; lateral fringe narrow, usually defining ambitus; oral spines 

 five or six, the two series webbed into a single scoop-shaped group at each mouth 

 angle; suboral spine pointed, hyaline, shorter than inner flattened mouth spine. 



Notes on North Pacific specimens. — Supplementing the description given by 

 Verrill of a specimen from Albatross station 2433, off Newfoundland Bank (No. 

 12004, U.S.N.M.), 57 fathoms, the following notes based on specimens from Bering 

 Sea and vicinity may be of value in showing the range of variation: 



Perrier's type measured R = 20 mm.; Verrill's, R = 32 to 35 mm., r = 22 mm., 

 R = about 1.5 mm. The largest specimen from station 3285, with seven rays, has 

 the following dimensions: R=82 mm., r = 50 mm.±, R = about 1.6 r. The largest 

 sLVrayed specimen, station 3282, measures R = 71 mm., r = 43 mm., R = 1.65 r; a 

 small specimen, R = 24 mm., r=17 mm., R = 1.4 r. Twenty-one have six rays, 

 two have seven, four have eight, and one young extracted from the nidamental 

 cavity of an eight-rayed specimen has nine rays. The abactinal surface is well 

 arched, the rays usually swollen and the actinal surface slightly sunken. The general 

 appearance is shown by the figure. 



The supradorsal membrane is very tough and opaque, with muscle fibers (when 

 viewed from the inner surface), but not regularly reticulated. From the outside 

 no muscle bands show at all. The surface is either uniformly papillated with the 

 stout peripheral pseudopaxillar spines, or a few paxillee cause the surface to be 

 raised in warty humps (as shown by Perrier's figure), these latter in addition to the 

 usual spiny appearance. Spiracula very numerous; and usually in large specimens 

 groups or lines of two or more lie in furrows or dark creases of the skin. The smooth 

 interradial grooves vary in width and length, but there are no slits such as Verrill 

 found; these are formed periodically as he suggests. (See " Toung," on p. 365.) 

 Usually the area without spiracula extends about halfway from margin to osculum, 

 and is very narrow. (See also Doderlein, 1889, 1900.) 



Pseudopapillse stout, shorter abactinally than laterally, with robust cruciform 

 bases. Pedicel stout, abactinally a little higher than the spines. A specimen from 

 . 3251 has six to eight stout, often clavate, rough-tipped, blunt, slightly radiating, 

 peripheral spines and often a stout central spine to each pedicel. Surrounding the 

 central spine (between it and the peripheral six to eight) are from four to eight 

 very much slenderer spinules, which do not, as a rule, push up the supradorsal mem- 

 brane to an appreciable extent. One of the peripheral spines is usually much 

 enlarged with a blunt clavate tip which shows more prominently from the outside, 

 being thicker, heavier, and usually longer than the rest. The large seven-rayed 

 specimen has the same structure. The enlarged peripheral spine being well marked 

 and on some paxilla? greatly enlarged, especially on the dorsolateral surface of the 

 rays. Tips of spines minutely roughened. 



