88 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Genus LISSOMETRA A. H. Clark 



Anledon (part) A. H. CLARK, Proc. U. S. Nat. Mus., vol. 33, 1907, p. 145. 

 Thalassometra (part) A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 360. 

 Parametra (part) A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 214. 



Lissometra A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. 147 (in key; range), p. 

 160. GISLN, Kungl. Fysiograf. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, p. 20. 



Diagnosis. A genus of Tkalassometridae in which there is no appreciable expansion 

 of the earlier segments of the genital pinnules; the middle and distal brachials are some- 

 what compressed laterally and have an ill-defined median keel, but the division series 

 and arm bases are rounded dorsally with a strong median crest; the IIBr series are 2; 

 and the cirri are about one-third of the arm length with 30-34 segments. In the only 

 known species the 13-15 arms are 65 mm. long, and the cirri are 20 mm. long. 



Geographical range. Known only from the Eastern Sea off Kagoshima Gulf, 

 southwestern Japan. 



Bathymetrical range. Known only from 188 meters. 



History. The single species in this genus was described under the name Antedon 

 alboflava in 1907. Later in the same year, upon the establishment of the genus Thalas- 

 sometra, it was transferred to it. In 1912 it was listed as a species of Parametra. In 

 my memoir on the unstalked crinoids of the Siboga expedition published in 1918 

 Lissometra alboflava was listed under the genus Lissometra without any explanation; 

 the characters of the new genus were given in a key to the genera of the subfamily 

 Thalassometrinae. 



LISSOMETRA ALBOFLAVA (A. H. Clark) 



PLATE 11, FIGURE 34 

 [See also vol. 1, pt. 1, figs. 199, 200, p. 239; pt. 2, fig. 216, p. 161.] 



Antedon alboflava A. H. CLARK, Proc. TJ. S. Nat. Mus., vol. 33, 1907, p. 145 (description; Albatross 



station 4936). 

 Thaiassometra alboflava A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 360 (listed); 



Proc. U. S. Nat. Mus., vol. 34, 1908, p. 318 (Japan). 

 Parametra alboflava A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 214 (synonymy; locality); 



Journ. Washington Acad. Sci., vol. 5, No. 6, 1915, p. 215 (southern Japanese species; range and 



its significance). 

 Lissometra alboflava A. H. CLARK, Unstalked crinoids of the <Si6oga-Exped., 1918, p. 160 (references). 



Description. The centrodorsal is roughly hemispherical or bluntly conical, about 

 as broad at the base as high. The cirrus sockets are arranged in 15 crowded columns, 

 1 or 2 in each column. 



The cirri are X-XV, 30-34, 20 mm. long. Only the fifth, or fifth and sixth, seg- 

 ments are longer than broad. The sixth and following segments bear sharp dorsal 

 spines. The first 5 segments are dark in color with a dull surface and the remainder 

 are nearly white with a polished surface, the transition taking place on the distal end 

 of the fifth segment. The cirri are stout basally, but taper somewhat rapidly to the 

 distal end of the third segment after which point they remain slender. 



The disk is scantily plated. The brachial ambulacra are nearly naked. The 

 covering plates on the pinnules are small. The sacculi are numerous. 



The ends of the basal rays are just visible as minute tubercles in the interradial 

 angles of the calyx. 



