62 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Dorometra A. H. CLARK, Journ. Washington Acad. Sci., vol. 7, No. 5, 1917, p. 127 (referred to the 

 Antedoninae), p. 128 (type species Antedon nana Hartlaub, 1890; diagnosis; range; included 

 species); No. 16, p. 506 (in key; range); Unstalked crinoids of the Siboga-Exped., 1918, p. 198 

 (in key; range), p. 214 (key to the included species). GISLN, Nova Acta Reg. Soc. Sci. Upsali- 

 ensis, ser. 4, vol. 5, No. 6, 1922, p. 133. H. L. CLARK, Mem. Mus. Comp. Zool., vol. 55, 1938, 

 p. 47; Echinoderm fauna of Australia, 1946, p. 60 (in key), p. 62 (type species; range; key to 

 Australian species). 



Diagnosis. A genus of Antedoninae in which P 3 is much the longest and stoutest 

 pinnule on the arm; there are rarely over XL cirri, of which the segments, not over 17 in 

 number, have produced distal ends that overlap the proximal ends of those succeeding; 

 the outer cirrus segments, except sometimes the distalmost, are much longer than their 

 proximal width; the brachials have smooth, or only very finely spinous distal edges; 

 and the arms are not known to exceed 60 mm., and are rarely 50 mm. in length. 



Type species. -Antedon nana Hartlaub, 1890. 



Geographical range. From southern Japan and the Bonin Islands to the Tonga 

 Islands and northern Australia and westward to the eastern coast of Africa, from 

 Mauritius and Madagascar to Suez. 



Bathymetrical range. From the shore line down to 728 meters. 



Thermal range. From the temperature of the tropical littoral down to 16.72 C. 



History. The first known species of Dorometra (parvicirra) was described by 

 P. H. Carpenter in 1888 under the generic name Antedon, the second (nana) was 

 described by Hartlaub under the same generic name in 1890, and the third (briseis) 

 was also described as an Antedon by the present writer in 1907. In 1908 Chadwick 

 mentioned a fourth species which, however, he did not distinguish from Carpenter's 

 parvicirra. 



In my first revision of the comatulids (1907) the species parvicirra, nana and briseis 

 were left in the genus Antedon; but in the second revision (1908) they were removed, 

 together with [Argyrometra] crispa, [Andrometra] psyche and [Annametra] minuta to 

 Iridometra, of which Antedon adrestine A. H. Clark, 1907, was the type species. Here 

 they remained until 1917 when, in a revision of the Antedoniclae, the genus Dorometra 

 was proposed, with the species nana, mauritiana, gracilis, briseis, parvicirra, aegyptica 

 and clymene. In 1936 the species andromacha A. H. Clark was added and in 1940 

 gracilis was reduced to the synonymy of nana by Dr. T. Gislen. 



[NOTE BY A.M.C.] As explained on p. 77, I believe that Eumetra aphrodite will 

 prove to be congeneric with Dorometra nana rather than with E. chamberlaini. If that 

 is so, then its position within the genus Dorometra is close to aegyptica and parvicirra. 



KEY TO THE SPECIES OF DOROMETRA 

 [Modified by A.M.C.] 



a 1 . P 2 intermediate in size and in number of segments between PI and Pj. 



6 1 . Cirri not especially slender, with up to 16 segments of which the longest are not more than about 



twice as long as the diameter of the expanded ends; P 3 with more numerous segments than P 2 . 

 c 1 . Cirri up to 10 mm. long when the arms are 40 mm. long (Bonin and Philippine Islands to Singa- 

 pore and Queensland; 0-164 meters) parvicirra (p. 63) 



c 2 . Cirri up to 13 rnm. long when the arms are 40 mm. long (Suez Bay; 18 meters). 



aegyptica (p. 67) 



6 2 . Cirri with 11-12 excessively slender and delicate segments, the earlier ones about four times a 



long as the diameter of their expanded ends, the penultimate twice as long as broad; P 3 with 



few, if any, more segments than P 2 (Moluccas; 95 meters) clymene (p. 68) 



a 2 . P 2 Resembling P, in size, or smaller. 



