PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 269 



onl}^ a slight angle with it, while the distal arm is smaller and narrower, making with 

 the main stem a considerabl}^ greater angle. Occasionally there is onl_v a spatulate 

 expansion of the outer end of the band. 



In Coccomctra hageni minute spicules have on occasion been detected in the tenta- 

 cles; none have been found in the other species. 



[Notes by A.M.C] In his John Murray Expedition report of 19.37 Mr. Austin 

 Clark described a new species and genus, Repomctra arabica, which he placed in the 

 Thysanometrinae. In trying to match this genus to the diagnosis of this subfamily 

 so many differences appeared, particular^ with regard to the cirri, that a possible 

 relationship with the other subfamilies of Antedonidae was sought. The low hemi- 

 spherical centrodorsal with irregularly alternating cirrus sockets ruled out relationship 

 with the Zenometrinae. The short, rather heavy cirri with no dorsal processes elimi- 

 nated the Perometrinae and BathjTnetrinae but suggested affinity with the Antcdoninae. 

 The Key to the genera of Antedoninae unfortunately relies largely on the characters 

 of the pinnules which are in very poor condition in the unique specimen of Repometra 

 arabica. However, this species appears to run dowaa to the genus Antedon and further 

 to A. iris, known from off Malaya to northwest Australia. No species of Antedon 

 has been recorded from the western Indian Ocean. A. serrata from China and Japan 

 has the segments of Pj rather short, approaching those of arabica and A. incommoda 

 has cirri which are practically identical in form and proportions. I am therefore 

 transferring arabica to the subfamily Antedoninae and considering Repometra as a 

 synonjTn of Antedon. 



KEY TO THE GENERA OF THYSANOMETRINAE 



a'. Distal pinnules longer than the proximal ones; P2 with the third segment as long as, or longer 

 than, broad, and the following segments markedly longer than broad; radial facets oblong, 

 broader than long (Admiralty and Philippine Islands northward to southern Japan; 128-548 

 meters) Thysanometra (p. 269) 



a'. Distal pinnules shorter than the proximal ones; P2 with the third segment Vjroader than long and 

 the fourth broader than long or about as long as broad; radial faces wedge-shaped, elongate 

 (Caribbean Sea northward to North Carolina; 14-1046 meters) Coccometra (p. 275) 



Genus THYSANOMETRA A. H. Clark 



Antedon (part) P. H. Carpenter, Proc. Roy. Soc, vol. 28, 1879, p. 384, and foUowing authors. 



Thysanometra A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 351 (diagnosis; type 

 species Antedon tenelloides A. H. Clark, 1907); Bull. Mus. Comp. Zool., vol. 51, No. 8, 1908, 

 p. 246 (same); Proc. U.S. Nat. Mus., vol. 34, 1908, p. 211 (referred to Antedonidae, restricted), 

 p. 212 (occurs in Japan); Amer. Nat., vol. 42, No. 500, 1908, p. 541 (only known from Indo- 

 Pacific-Japanese area) ; No. 503, p. 725 (color) ; Geogr. Journ., vol. 32, No. 6, 1908, p. 602 (charac- 

 teristic of the Indo-Japanesc region); Proc. Biol. Soc. Washington, vol. 21, 1908, p. 136 (referred 

 to Antedonidae); vol. 22, 1909, p. 177 (referred to Thysanometrinae); Proc. U.S. Nat. Mus., vol. 

 40, 1911, p. 10 (represented in West Indies by Coccometra); Crinoids of the Indian Ocean, 1912, 

 p. 11 (absent from the west coast of the Malay peninsula, the Andamans, and from farther west), 

 p. 14 (corresponds to the West Indian Coccometra), p. 26 (range; rehition to Coccometra), p. 62 

 (in kej'), p. 244 (original reference; type); Internat. Rev. gesamt. Hydrobiol. und Hydrogr., 

 1914, pp. 6 and following (represents Coccometra in the Indo-Pacific; range); Die crinoiden der 

 Antarktis, 1915, p. 182 (range; represented in the Atlantic by Coccometra); Journ. Washington 

 Acad. Sci., vol. 7, 1917, No. 5, p. 127 (referred to the Thysanometrinae) ; No. 16, p. 506 (in key; 

 range); Unstalked crinoids of the Sihoga-TL-K-pcA., 1918, p. 217 (in key; range), p. 218 (key to the 

 included species) ; John Murray E.xpcd. 1933-34, Sci. Reports, vol. 4, No. 4, 1937, p. 94. — H. L. 

 Clark, Mem. Mus. Comp. Zool., vol. 55, 1938, p. 47. 



