196 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Siboga station 315; anchorage east of Sail us Besar, Paternoster Islands; down to 

 36 meters; January 17-18, 1900 [A. H. Clark, 1912, 1918] (1, Amsterdam Mus.). 



Danish Expedition to the Kei Islands; Dr. Th. Mortensen; station 101; Java Sea; ' 

 49 meters; sand, stones, and sponges; August 5, 1922 (7). 



Oeographical range. From southwestern Japan southward to the Kei Islands, 

 and westward to the Java Sea. 



Bathymetrical range. From 9 to 90 meters. 



History. This species was first described under the name Prometra parva by 

 me in 1912 from a single specimen dredged by the Siboga at station 315. In 1918 

 it was redescribed and figured under the name Decametra parva, and additional speci- 

 mens were recorded from Siboga station 260 and from Albatross station 5557. 



DECAMETRA MINIMA (A. H. Clark) 



PLATE 25, FIGURE 131 



Prometra minima A. H. CLARK, Ann. Mag. Nat. Hist., ser. 8, vol. 10, 1912, p. 38 (description; Siboga 

 station 117). 



Decametra minima A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. viii (discovery 

 by the Siboga and its significance), p. 118 (in key; range), p. 121 (detailed description; stations 

 79a, 117, 144, 260; also Albatross station 5248), pp. 272, 273, 275 (listed), pi. 20, fig. 45. 



Diagnostic features. The cirri are X, 10-12, 3-4 mm. long, with the fifth or sixth 

 and following segments about as long as broad; P 2 is 3 mm. long with 8 or 9 segments, 

 stiff and spinelike, though slender; PI is 2 mm. long with 8 or 9 segments; P 3 is small 

 and slender, with 8 segments; the arms are 35-40 mm. long and very slender. 



Description. The centrodorsal is thin discoidal with the dorsal pole flat and 

 finely papillose, 1 mm. in diameter. 



The cirri are X (rarely any other number), 10-12, from 3 to 4 mm. long. The 

 first segment is short and those following increase in length to the fifth or sixth which, 

 with the succeeding, is about as long as broad. The second and following have a 

 finely serrate transverse ridge which becomes median in position after the fourth or 

 fifth, low and very narrow, appearing as a very minute sharp spine in lateral view. 

 On the second-fourth segments the lateral angles of this ridge project beyond the 

 borders of the cirrus segments as viewed dorsally, but from that point onward it be- 

 comes narrower, beyond the sixth dividing more or less completely into two trans- 

 versely oblong sharp ridges or small sharp spines. The antepenultimate segment 

 bears a single spine. The opposing spine is much larger than the spine on the seg- 

 ment preceding. 



The radials are just visible beyond the rim of the centrodorsal. The IBrj are very 

 short, about four times as broad as long, with the proximal and distal edges straight 

 and parallel and the lateral edges converging slightly; there are slight rounded ventro- 

 lateral projections. The IBr 2 (axillaries) are broadly pentagonal, half again as broad 

 as long. Synarthrial tubercles are moderately developed. Like the IBr 1; the IBr 2 

 and first brachials have slight rounded ventrolateral processes. 



The 10 arms are from 35 to 40 mm. long and very slender, resembling those of the 

 other species of the genus. On the lower oblong brachials there is a faintly indicated 

 rounded median carination. 



P! is 2 mm. long, nearly as stout basally as P 2 , but tapering more rapidly and 

 becoming slender and delicate distally, composed of 8 or 9 segments of which the first 



