200 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



segment. The cirri in dorsal view are much compressed basally, increasing in width 

 to the third or fourth segments, which are about twice as broad as the first segment, 

 then tapering gradually for about three segments, after which they remain of prac- 

 tically uniform width. The first three segments are sharply flattened laterally. 

 PI is 7.5 mm. long with 18 segments of which the first is more than twice as broad 

 as long, the second is somewhat longer than broad, the third is about as long as 

 broad, and the remainder are slightly longer than broad. The pinnule is perfectly 

 smooth. P 2 is 7.8 mm. long with 18 or 19 segments, resembling Pj but slightly stouter 

 and stiff er. P 3 is 6 mm. long with 16-19 segments, resembling P, but slightly stouter 

 in the outer portion. The pinnules following are small and weak. P tt is absent. 

 Except for being much larger, this specimen very closely resembles the type. 



One of the three specimens from Sipankot has the arms 50 mm. long; the cirri 

 are X, 18-20, 8 mm. long; Pj has 14 segments P 2 has 18 segments. The other two 

 are smaller. These very closely resemble D. informis, but are distinguished by the 

 smooth P 2 , which has more numerous segments. 



The specimen from the Boo Islands is small. 



Localities. Siboga station 213; Island of Salayer, south of Celebes; reef; October 

 26, 1899 [A. H. Clark, 1912, 1915, 1918] (1, Amsterdam Mus.). 



?Hong Kong; United States North Pacific Exploring Expedition; according to 

 Hartlaub this specimen is M. C. Z., 2698; in addition to this number he found No. 25 

 on a bit of paper in the jar with it, and No. 90 on the jar itself. 



Obi latoe; shore and reef; Willebrord Snellius, April 23-27, 1930 [A. H. Clark, 

 1936] (1, L. M.). 



Sipankot, near Sibutu, Sulu (Jolo) Archipelago; 3-6 meters; Willebrord Snellius, 

 September 10-14, 1929 [A. H. Clark, 1936] (3, L. M.). 



Boo Islands; Willebrord Snellius, October 5, 1930 [A. H. Clark, 1936] (1, L. M.). 



Geographical range. From Salayer, south of Celebes, and Obi latoe, south of 

 Halmahera (Gilolo), northward to the Sulu (Jolo) Archipelago and ?Hong Kong. 



Bathymetrical range. From the shore line down to 3 (?6) meters. 



History.- Hartlaub's Antedon sinensis, described in April 1912 from a specimen 

 from Hong Kong, is probably this species. The species was described by me as 

 Prometra laevipinna in July 1912 from a single specimen that had been collected by 

 the Siboga at Salayer. In my report on the unstalked crinoids of the Siboga expedi- 

 tion published in 1918 it was redescribed in detail and figured. In my report on the 

 unstalked crinoids of the Willebrord Snellius expedition published in 1936 I recorded 

 and gave notes on one specimen from Obi latoe and three from Sipankot, and recorded 

 a fifth from the Boo Islands. 



DECAMETRA STUDERI (A. H. Clark) 



PLATE 24, FIGURE 121 



Oligometra studeri A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 41 (description; 



Dirk Hartog Island, 7 fms.), p. 88 (should have been referred to Cyllometra) ; Die Fauna Siid- 



west-Australiens, vol. 3, Lief. 13, 1911, p. 437 (history; belongs in Decametra), p. 443 (range); 



Proc. U. S. Nat. Mus., vol. 43, 1912, p. 384 (belongs in Decametra). HARTMEYER, Mitt. 



Zool. Mus. Berlin, vol. 8, No. 2, 1916, p. 237 (No. 6381). 

 Cyllometra studeri A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 88 (sluderi correctly 



placed); Zool. Anz., vol. 34, No. 11/12, 1909, p. 368 (Dirk Hartog Island, 7 fms.); Proc. U. S. 



Nat. Mus., vol. 40, 1911, p. 31 (arms compared with those of Decametra mobiusi). 



