518 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



PSATHYROMETBA ERYTHRIZON (A. H. Clark) 



[See vol. 1, pt. 1, figs. 212-213 (p. 241); pt. 2, figs. 117 (p. 79), 295 (p. 221)] 



Antedon erythrizon A. H. Clark, Proc. U.S. Nat. Mus., vol. 33, 1907, p. 79 (description; Alhatrnss 

 sta. 4981).— SowERBY, The naturalist in Manchuria, Tientsin, vol. 5, 1930, p. 79. 



Psalhyrometra erythrizon A. li. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 353 (listed); 

 Crinoids of tlie Indian Ocean, 1912, p. 234 (synonymy; locality); Journ. Washington Acad. Sci., 

 vol. 5, 1915, No. 3, p. 81 (in the arctic fauna of the Okhotsk and Japan Seas; probably an intrusion 

 here under present conditions); No. 6, p. 213 (antarctic; entry into Okhotsk and Japan Seas), 

 p. 215 (member of the Japanese arctic fauna; range and its significance); Die Crinoiden der 

 Antarktis, 1915, p. 115 (range); Unstalkcd crinoids of the -Si6o?o-Exped., 1918, p. 224 (in key; 

 range), p. 226 (references).— Gisl£n, Ark. Zool., vol. 15, No. 23, 1923, p. 15.— A. H. Clark, 

 Explorations des mers de I'U.R.S.S., vol. 23, 1937, p. 218 (in key; locality and range), pp. 221, 222 

 (in Russian), p. 224 (in key; synonymy; range), pp. 229, 230. 



Diagnostic features. — The centrodorsal is broadly truncated, about as high as it is 

 broad at the base; the cirrus sockets are arranged in 3 columns in each radial area, 

 which are separated by bare interradial bands; the cii-ri are about LXV, 35-40 and 

 about 50 mm. long when the arm length is 140 mm. ; Pi with 16 segments is about 20 mm. 

 long; P2 is shorter, 15 mm., with 12 segments, and the following pinnules become at first 

 still shorter and then more elongate. 



Description. — The centrodorsal is truncated conical, 6 mm. broad at the base and 

 6 mm. high, with nearly straight sides and a concave dorsal pole 2 mm. in diameter. 

 The cirrus sockets, which are oblong \\-ith broadly rounded corners, longer dorsoventrally 

 than transversely, are arranged in 3 regular columns in each radial area, there being 4 

 or 5 sockets in each column which decrease gradually in size from the periphery to the 

 dorsal pole. The sockets in each column are usually in touch with tliose above and 

 below. The columns may be in contact or separated by very narrow Imes. The 

 radial areas are delimited by bare interradial bands that run from the periphery to the 

 dorsal pole and gradually decrease in width and which are nearly or quite as broad as 

 the sockets of the adjacent columns. 



The cirri are about LXV, 35-40, about 50 mm. long, strongly compressed laterally. 

 The first segment is short, the second and third are about as long as broad, the fourth 

 is half again as long as broad, the fifth is twice as long as broad, and the following are 

 about 3 times as long as broad, after the twenty-second slowly decreasing in length to 

 the antepenultimate, which is twice as long as broad, and the penultimate, which is 

 about as long as broad. The terminal claw is very small. 



The ends of the basal rays are visible as small tubercles continuuig the interradial 

 lines of the centrodorsal to the interradial angles of the caly.x and bridging over the 

 narrow subradial clefts. 



The radials are very short in the median line, but extend well upward in the 

 angles of the calyx where the truncate tip of the triangle formed by two adjacent 

 radials separates the bases of the IBr,. The IBri are short and very deeply incised 

 by the proximal projection from the axillary. The IBr2 (axillaries) are as long as 

 broad, 4 mm. long by 4 mm. broad, with all the sides, especially the two distal, con- 

 cave and the proxinuxl angle as well as the distal sharp; the lateral angles do not touch 

 those of their neighbors. The dorsal surface of the IBr scries is high and well-rounded. 

 On the line of union between the IBri and IBr.2 there is a strong articular tubercle 

 which in profile makes an angle of about 120° and shows a slightly blunted apex. 



