520 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Psathyrometra major A. H. CLARK, Rec. Indian Mus., vol. 7, pt. 3, No. 26, 1912, p. 270 (Investigator 

 sta. 115; nomen nudurri); Notes Leyden Mus., vol. 34, 1912, p. 140 (description; Siboga sta. J45); 

 Die Crinoiden der Antarktis, 1915, p. 116 (range), p. 117 (characters of the centrodorsal ; com- 

 parison with Ps. antarctica) ; Unstalked crinoids of the Sibopa-Exped., 1918, p. 224 (in key; 

 range), p. 226 (references; notes; sta. 45; Investigator sta. 115), fig. 12, p. 227, p. 271 (listed), pi. 

 26, fig. 87. 



Psalhyrometra inusitata A. H. CLARK, Rec. Indian Mus., vol. 7, pt. 3, No. 26, 1912, p. 270 (nomen 

 nudum; 7 miles SE. by S. from Ross I., 265 fms.); Notes Leyden Mus., vol. 34, 1912, p. 141 

 (description; Siboga sta. 45); Die Crinoiden der Antarktis, 1915, p. 116 (range); Unstalked cri- 

 noids of the Siboga-Exped., 1918, p. viii (discovery by the Siboga and its significance), p. 225 

 (in key; range), p. 229 (detailed description; stas. 38, 45, 178, 314, 316; 7 miles SE. from Ross 

 I., 265 fms.), fig. 13, p. 229, pp. 271, 274, 276 (listed), pi. 26, figs. 88, 89. GISLN, Nova Acta 

 Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 140. 



Psathyrometra, sp. A. H. CLARK, Unstalked crinoids of the Siboga-'Exped., 1918, p. 231 (sta. 38), p. 

 271 (listed). 



Psathyrometra wireni GISLN, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 

 138, figs. 128-132, p. 134, pi. 2, fig. 12 (description; Sixten Bock's sta. 6); Ark. Zool., vol. 15, 

 No. 23, 1923, p. 15; Zool. Bidrag Uppsala, vol. 9, 1924, p. 82; Vid. Medd. Nat. Foren. K0benhavn, 

 vol. 83, 1927, p. 3 (stas. 6, 18; 360-450 meters), p. 47 (stations; notes), pp. 68, 69 (listed). 



Diagnostic features. The centrodorsal is almost as high as it is wide at the base 

 in large specimens but relatively lower in small ones; five interradial furrows separate 

 the crowded cirrus sockets into radial groups of usually 2 converging lateral columns 

 and a shorter median one (the latter absent in small specimens); the cirri are about 

 XLV, with up to 29 segments and 55 mm. long; P! has 20 to 30 segments and is very 

 slender; P 2 may be similar or stouter and shorter with fewer segments. 



Description. The centrodorsal is nearly conical with straight sides and the tip 

 slightly blunted, usually nearly as high as broad at the base, in large individuals such 

 as the type specimen of Ps. major about 5.5 mm. in basal diameter and 5.0 mm. high. 

 [NOTE BY A.M.C. : This is the length from the apex to the interradial border; the vertical 

 height would probably be a little less, about 4.2 mm.] The sides are divided into five 

 radial areas by five interradial furrows, from shallow and U-shaped to deep and V-shaped, 

 which are nearly or quite as broad as the adjacent cirrus sockets. The sockets in 

 each radial area are closely crowded and are arranged in two marginal converging 

 columns of three or four each with a short median column of from one to three (usually 

 two) sockets between the proximal ends of the converging lateral columns which meet 

 beyond it. 



Very few fully developed cirri have been observed; the type of Ps. major has one 

 entire cirrus and another with a broken tip. These are 55 mm. long and consist 

 of 29 segments, of which the first is very short, the second is about twice as broad as 

 long, the third is slightly longer than broad, the fourth is about twice as long as the 

 diameter of the expanded distal end, the fifth is nearly or quite three times as long as 

 the distal width, the sixth to ninth or tenth are slightly longer than the fifth, and the 

 following ones decrease almost imperceptibly in length so that the nineteenth and 

 following are about twice as long as broad. From the twenty-third segment onward 

 the cirri taper to a very slender tip, and the segments increase in relative length so that 

 the distalmost are five or six times as long as broad. From the third onwards in lateral 

 view the segments are gently concave both dorsally and ventrally so that the articu- 

 lations are prominent; but this feature decreases and disappears in the relatively 

 short distal segments. The cirri are moderately compressed laterally throughout 

 their entire length. 



