•JS BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Description. — The centrodorsal is low hemispherical or rounded discoidal with the 

 apical area spinous, bearing 10 columns of cirrus sockets, 2 to each column. 



The cirri are XX, 65-75, from 40 mm. to 45 mm. in length. The first 4 or 5 seg- 

 ments are very short, and those following are longer than broad, the seventh-ninth, 

 which are the longest, being somewhat less than twice as long as broad. The succeeding 

 segments gradually become shorter, about as long as broad just beyond the middle of 

 the cirrus and very short distally. Dorsal spines are developed in the distal third of 

 the cirri. 



The disk, and the brachial and pinnule ambulacra are well plated. 

 The ends of the basal rays are visible as small tubercles in the angles of the calyx. 

 The radials are veiy short, crescentic, and are furnished with a fringe of spines 

 along the superior border. The IBr! are very short, deeply incised by the axillaries, 

 and are furnished with a fringe of teeth about their entire edge. The IBr 2 (axillaries) 

 are rhombic, about twice as broad as long, with the sides slightly incurved and with a 

 strong rounded median keel in the proximal half which continues into a similar keel 

 on the first brachials. 



Arms 10-11 (in all but one case 10) in number, 60 mm. long. The first 8 brachials 

 are roughly oblong with irregular lateral dentate processes and a faintly marked median 

 keel which is most prominent on the. first and second. The following brachials are wedge- 

 shaped becoming gradually shorter and more compressed laterally and developing a 

 sharp median keel and long median overlapping spines. The terminal brachials become 

 longer again. The elements of the division series and the first 4 brachials are sharply 

 flattened laterally and are in close lateral apposition. 



P] is the longest, about 5 mm. in length, very stout, composed of 8-10 segments 

 of which the basal 5 are large, massive, and about as long as broad and the remainder 

 are small and rapidly diminish in size. This pinnule is very sharply prismatic and 

 strongly flattened exteriorly; its distal border is furnished with a strong lateral ridge 

 on either side Inning a more or less deep groove between. The following pinnules 

 decrease in length to P 6 which is 3.5 mm. long with the first segment large and about 

 as long as broad and the remainder tapering rapidly to a point, then gradually increase 

 distally becoming rather slender and reaching a length of about 8 mm. with 15-18 

 segments of which the first 2 are enlarged and the remainder are somewhat longer 

 than broad. All the pinholes are prismatic and strongly carinate. 



Locality. — Albatross station 4903; Eastern Sea, between 10 and 20 miles southwest 

 of the Goto Islands; Ose Saki Light bearing N. 22° E., 6 miles distant (lat. 32°31' 10"N., 

 long. 12S°33'20" E.); 196-254 meters; gray sand and broken shells; August 10, 1906 

 [A. H. Clark, 1907, 1908, 1909, 1912, 1915, 1918; Gislen, 1922] (5, U.S.N.M., 22632 

 [type], 35595). 



History. — This species was described under the name of Antcdon harm, in 1907 

 from five specimens that had been dredged by the Albatross at station 4903 in the pre- 

 ceding year. Later in 1907 it was transferred to the new genus Thalassometra, and in 

 1908 it was listed from Japan as Thalassometra harm. In 1909 it was transferred to the 

 new genus Stenometra, and in 1912 it was compared with the new species Stenometra 

 acuta (=Daidalometra arachnoides) . Later in 1912, in my memoir on the crinoids of 

 the Indian Ocean, it was listed and the synonymy and range were given. 



