PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 75 



In 1910 I examined the specimen from Tonga in the Hamburg Museum, and later 

 (1912) published a confirmation of Hartlaub's identification of it. In 1912 also nana 

 was recorded from the Andamans where it had been found by the Investigator. 



In 1915 Dr. H. L. Clark recorded it from Mer Island in Torres Straits and described 

 its swimming movements, publishing additional notes upon it in 1921. 



In 1918 it was recorded from two new localities where it had been found by the 

 Siboga, and in 1922 Dr. Torsten Gisldn recorded it from the Bonin Islands and gave 

 copious notes regarding the structure of the specimens. 



Antedon nana was removed to Iridometra at the time of the creation of that genus 

 in 1908, and was made the type of the genus Dorometra in 1917. 



In 1940 Dr. T. Gislen decided that Dorometra ijracilis A. H. Clark, of which only a 

 single specimen was known, came within the range of variation of D. nana. [NOTE 

 BY A.M.C.] In the absence of any directive from Mr. Clark on this point, I have 

 followed Gislen in regarding gracilis as a synonym. 



Remarks. -Dr. H. L. Clark (1915) stated that this is a very active species, in con- 

 trast to most of the other comatulids which he collected at Mer. The account quoted 

 from him of the swimming of 10-armed specimens (part 2, p. 603) refers to this species, 

 though he gave no indication of this in his original paper. 



While the Albatross was anchored off Sulu a young individual of this species about 

 half the adult size was captured at the surface while swimming about a submerged 

 electric light. It was said to have been swimming entirely by means of its cirri, with 

 the arms widely extended. 



This is probably a common species throughout the Indo-Malayan region; the 

 infrequency of the records may result from its being very generally overlooked because 

 of its small size. 



DOROMETBA I1RISKIS (A. H. Clark) 



Anledon briseis A. H. CLARK, Proc. U.S. Nat. Mus., vol. 33, 1907, p. 83 (Albatross Sta. 4876; descrip- 

 tion), p. 84 (compared with A. [Dorometra] nana); Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, 

 p. 341 (comparison with A. minula) p. 353 (listed); Bull. Mus. Comp. Zool., vol. 51, Xo. 8, 1908, 

 p. 241 (relation to A. psyche). SOWERBT, The Naturalist in Manchuria, Tientsin, vol. 5, 1930, 

 p. 79. 



Iridometra briseis A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 131 (listed); Proc. U.S. 

 Nat. Mus., vol. 34, 1908, p. 318 (Japan); Crinoids of the Indian Ocean, 1912, p. 231 (synonymy; 

 southern Japan, 59 fins.); Journ. Washington Acad. Sci., vol. 5, No. 6, 1915, p. 215 (southern 

 Japanese species; bathymetrical and thermal ranges and their significance). 



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

 Unstalked Crinoids of the Siboga-Exped., 1918, p. 215 (in key; range), p. 216 (references). 

 GISLEN, Nova Acta Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 5 (listed; depth; 

 Sagami Bay), p. 135 (localities; notes), p. 181 (listed), figs. 120-122, p. 134. 



Diagnostic features. P 3 is much less than twice as long as P, and P 2 , and P 2 is 

 slightly shorter than PI; the cirri have usually 11 to 14 segments of which the longest, 

 the third to fifth, are from three to three and a half times as long as broad with much 

 expanded ends. The arms are from 20 to 45 mm. and the cirri are from 7 to 11 mm. 

 (usually about 8 mm.) in length. 



Description. The centrodorsal is discoidal or low hemispherical, the dorsal pole 

 papillose; the cirrus sockets are arranged in two or three irregular marginal rows. 



The cirri are XX-XLVII, 9-17 (usually 11-14), the longest from 7 to 11 mm. 

 (usually about 8 mm.) in length. The first segment is about as long as broad, the 



