72 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



A. H. CLARK, Proc. U.S. Nat. Mus., vol. 33, 1907, p. 84 (compared with A. briseis); Smithsonian 

 Misc. Coll., vol. 50, 1907, pt. 3, p. 337 (representative of a small group characteristic of the East 

 Indian region), p. 353 (listed). HAMANN, Bronn's Klassen und Ordnungen des Tier-Reichs, vol. 

 2, Abt. 3, 1907, p. 1579 (listed). A. H. CLARK, Bull. Mus. Comp. Zool., vol. 51, No. 8, 1908, p. 241 

 (relation to A. psyche); Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 2 (of Hartlaub, 1890, 

 189l = Iridometra nana); Crinoids of the Indian Ocean, 1912, p. 37 (same). 



Antedon macropygus (Ltitken, MS.) HARTLAUB, Nova Acta Acad. German., vol. 58, No. 1, 1891, p. 89 

 (name identified). A. H. CLARK, Vid. Medd. Nat. Foren. K0benhavn, 1909, p. 117 (same). 



Iridometra nana A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 131 (listed) ; vol. 22, 1909, 

 p. 87 (record of a specimen swimming about a submerged electric light) ; Vid. Medd. Nat. Foren. 

 K0benhavn, 1909, p. 192 (Nicobar Is.; Singapore); Proc. U.S. Nat. Mus., vol. 36, 1909, p. 362 

 (resemblance to Comatilia iridomelriformis); vol. 40, 1911, p. 41 (compared with I. mauritiana) ; 

 vol. 43, 1912, p. 405 (compared with I. mauritiana) ; Notes Leyden Mus., vol. 34, 1912, p. 138 

 (compared with I. gracilis) ; Crinoids of the Indian Ocean, 1912, p. 25 (range of this and related 

 types), p. 37 ( = A. nana Hartlaub, 1890), p. 231 (synonymy; Andaman Is.; Male, Maldives); 

 Smithsonian Misc. Coll., vol. 60, No. 10, 1912, p. 2 ( = A. nana Hartlaub, 1890, 1891), p. 32 

 (Tonga Is.); vol. 61, No. 15, 1913, p. 53 (arms compared with those of /. aegyptica); (non I. nana, 

 p. 54= D. mauritiana, A.M.C.). H. L. CLARK, Carnegie Inst. Washington, Publ. 212, 1915, p. 106 

 (Mae'r; notes). 



Iridomelra gracilis A. H. CLARK, Notes Leyden Mus., vol. 34, 1912, p. 138 (description; Siboga Sta. 

 220). 



Ten-armed specimens, H. L. CLARK, Carnegie Inst. Washington, Publ. 212, 1915, p. 110 (mechanism 

 of swimming). 



Dorometra nana A. H. CLARK, Journ. Washington Acad. Sci., vol. 7, 1917, No. 5, p. 128; Unstalked 

 crinoids of the Siboga-~Exped., 1918, p. 215 (in key; range), p. 216 (synonymy; Stas. 144, 250), 

 pp. 273, 274 (listed); Smithsonian Misc. Coll., vol. 72, 1921, No. 7, p. 24 (swimming). H. L. 

 CLARK, The echinoderm fauna of Torres Strait, 1921, p. 25 (Mer; notes). GISLN, Nova Acta 

 Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 5, p. 133 (locality; notes), p. 182 (listed); 

 figs. 123, 124, p. 134; Ark. Zool., vol. 19A, No. 32, 1928, p. 10 (notes); Kungl. Fysiogr. Sallsk. 

 Lund Forh., vol. 7, No. 1, 1936, p. 5. A. H. CLARK, Temminckia, vol. 1, 1936, p. 317 (Kera, near 

 Timor and Beo, Talaud Islands) ; John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1937, 

 p. 102 (range), p. 103. GISLN, Kungl. Svenska Vet.-Akad. Handl., ser. 3, vol. 18, No. 10, 1940, 

 p. 15 (Marshall Is.; gracilis a synonym), pi. 2, figs. 9-11. H. L. CLARK, Echinoderm fauna of 

 Australia, 1946, p. 62 (in key; references; distribution). 



Dorometra gracilis A. H. CLARK, Journ. Washington Acad. Sci., vol. 7, 1917, No. 5, p. 128 (listed); 

 Unstalked crinoids of the Szboj/o-Exped., 1918, p. 215 (in key; range; references; description; Sta. 

 220), p. 274. GiSLfiN, Kungl. Svenska Vet.-Akad. Handl., ser. 3, vol. 18, No. 10, 1940, p. 15 (a 

 synonym of D. nana). 



Diagnostic features. PI and P 3 are similar, with usually 8 to 10 segments, only 

 half as long as P 3 , which has 13 to 16 segments; the cirri have 10 to 14 (usually 10 to 

 12) segments of which the longest, the fourth to seventh, are from two to three times 

 as long as broad with much expanded ends, and the antepenultimate is half as long 

 again as broad. The arms are from 25 to 60 mm. (usually between 30 and 45 mm.) 

 and the cirri are from 4 to 9 mm. in length. 



Description. The centrodorsal is moderately large, low hemispherical to almost 

 discoidal, with the cirrus sockets arranged in three irregular rows. The dorsal pole is 

 flat, 0.5 mm. in diameter. 



The cirri are XXX-LI, 10-14 (usually 10-12), from 4 to 9 mm. (usually from 6 

 to 8 mm.) in length, and very delicate. The first segment is short, the second is about 

 as long as broad, the third is from half again to twice as long as broad, and the fourth 

 to seventh, which are the longest, are from two to three tunes as long as broad; the 

 following segments become shorter, so that the antepenultimate is half again as long 

 as broad, and the penultimate is a third again as long as broad. The last bears a sharp 



