A MONOGRAPH OF THE EXISTING CRINOIDS 355 



flangelike border which persists as far as the fourth or fifth brachial; and the 10 arms 

 are 100-110 mm. long. 



Geographical range. — From Celebes to southwestern Japan. 



Bathymetrical range. — From 660 to 1,327 meters. 



Thermal range.— From 5.44° to 5.95° C. 



History. — The genus Poecilometra was established in 1907 to include Carpenter's 

 Antedon acoela, the type species, and another species that had been described a few 

 months earlier from southern Japan. The genus has since been maintained in its 

 original significance. 



KEY TO THE SPECIES IN THE GENUS POECILOMETRA 



a 1 . Centrodorsal large and broad, in large specimens about 5 mm. in diameter at the base; the profile 



of the IBr series and arm bases makes only a very slight angle with the dorsoventral axis; the 



IBr series are usually, though not always, somewhat constricted so that the arm bases broaden 



rather suddenly above them; the cirri are XXV-XXX, 15-18; the arms are about 100 mm. long 



(northern Celebes to Mindanao; 914-1,327 meters) acoela (p. 355) 



a J . Centrodorsal smaller, 4 mm. in diameter at the base; the profile of the IBr series and arm bases 

 makes an angle of about 60°, or about 30° with the dorsoventral axis; there is no constriction of 

 the IBr series; the cirri are about XX, 20; the arms are 110 mm. long (southwestern Japan; 

 660 meters) scalaris (p. 359) 



POECILOMETRA ACOELA (P. H. Carpenter) 



[See vol. 1, pt. 1, figs. 7, 8, p. 63, 277, p. 260, 493, p. 367; pt. 2, pi. 3, figs. 988, 989, pi. 14, figs. 1057, 

 1058, 1061, pi. 26, fig. 1161, pi. 27, fig. 1169.] 



Antedon sp. P. H. Carpenter, Pop. Sci. Rev., vol. 4, No. 15, 1880, pi. 6, fig. 10 (side and covering 

 plates of a pinnule). 



Antedon acoela P. H. Carpenter, Challenger Reports, Zoology, vol. 11, part 32, 1884, pp. 57, 83, 

 84, 93, 109, 110, 113, 128, pi. 54, figs. 1-4; pi. 55, fig. 5; Quart. Journ. Micr. Sci., vol. 27, 1887, 

 p. 391 (sacculi), pi. 30, fig. 3 (side and covering plates); Challenger Reports, Zoology, vol. 26, 

 pt. 60, 1888, p. 132 (description; Challenger station 214), pi. 2, figs. 3, a-d; pi. 16, figs. 1-5.— 

 Hartlatjb, Nova Acta Acad. German., vol. 58, No. 1, 1891, p. 113 (in Gottingen Mus.).— 

 Shipley and MacBride, Zoology, 1901, p. 269, fig.— Minckert, Arch. Naturg., Jahrg. 71, 1905, 

 vol. 1, Heft 1, p. 190 (syzygies and regeneration). — Hamann, Bronn's Klassen und Ordnungen 

 des Tier-Reichs, vol. 2, Abt. 3, 1907, p. 1578 (listed), pi. 12, fig. 1 (from Carpenter).— A. H. 

 Clark, Crinoids of the Indian Ocean, 1912, p. 33 (identity). 



Poecilometra acoela A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 302 (listed); Proc. 

 Biol. Soc. Washington, vol. 22, 1909, p. 18 (listed); Crinoids of the Indian Ocean, 1912, p. 33 

 (identity), p. 225 (synonymy; locality); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 50 

 (published references to specimens in the B. M.; Challenger station 214; comparison with P. scalaris) ; 

 Unstalked crinoids of the Si6offa-Exped., 1918, p. 190 (in key; range; references; notes; stations 

 122, 124), p. 273 (listed).— Gislen, Zool. Bidrag Uppsala, vol. 9, 1924, p. 280. 



Diagnostic features.— The lateral profiles of the IBr series are almost parallel, 

 those of the arm bases slightly diverging; the IBr series are constricted so that there 

 is a sudden broadening at the first brachial; in small individuals in which the constric- 

 tion of the IBr series has not developed the profiles of the proximal portion of the 

 animal diverges at an angle of about 45°; the centrodorsal is large and broad, up to 

 5 mm. across at the base; the cirri are XXV-XXX, 15-18; and the arms arc up to 

 100 mm. long. 



Description.— The centrodorsal is subcorneal or hemispherical. The cirrus sockets 

 are evenly distributed and are arranged roughly in 2 rows anil from 10 to 15 columns. 



