176 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



more completely to the ventral side of the segments and finally crowded out alto- 

 gether. The brachial articulations are rich reddish purple, in sharp and handsome 

 contrast to the brachials themselves. The oral surface of the pinnules is very dark, 

 almost black. 



Locality. Australian Fisheries Investigation steamer Endeavour; 11 miles east- 

 southeast of Clarence River mouth, New South Wales; 64-66 meters [H. L. Clark, 

 1916] (1, Austr. M.). 



History. This species was originally described in 1916 by Dr. Hubert Lyman 

 Clark under the name Oligometra zebra from a single specimen dredged off the mouth 

 of the Clarence River, New South Wales, in 35-36 fathoms by the Australian Fish- 

 eries Investigation steamer Endeavour. 



DECAMETRA CHADWICKI A. H. Clark 



PLATE 26, FIGURES 139, 140 



Antedon serripinna CHADWICK, Journ. Linn. Soc. (Zool.), vol. 31, 1908, p. 44 (Suez Bay, 10 fms.; 

 notes). BOULENGER, Proc. Zool. Soc. London, 1913, p. 88 (Suez Bay, 10 fms.; myzostomes) , 

 p. 102 (same). A. H. CLARK, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 5 (identity); Crinoids 

 of the Indian Ocean, 1912, p. 41 (same). 



Oligometra serripinna A. H. CLARK, Amer. Nat., vol. 43, 1909, p. 254 (Red Sea; possibly the species 

 of which Moseley analyzed the coloring matter), p. 255 (reported from the Red Sea by Chad- 

 wick); Vid. Medd. Naturh. Foren. K0benhavn, 1909, p. 179 (in part; record from the Red 

 Sea). 



Colobometra chadwicki A. H. CLARK, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 5 (=Antedon serripinna 

 Chadwick, 1908), p. 9 (occurs on the northeast coast of Africa), p. 30 (synonymy; description; 

 Suez Bay, 10 fms.); Crinoids of the Indian Ocean, 1912, p. 41 (identity), p. 168 (synonymy; 

 locality). 



Colobometra (Prometra) chadwicki A. H. CLARK, Crinoids of the Indian Ocean, 1912, p. 322 (com- 

 pared with C. [P.] brevicirra). 



Prometra chadwicki A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. 125 (in key; 

 range). GISLEN, Vid. Medd. Dansk Naturh. Foren., vol. 83, 1927, p. 28 (comparison with 

 P. perplexa). 



Decametra chadwicki A. H. CLARK, John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 

 1936, p. 100 (range), p. 104. 



Diagnostic features. The cirri are 12-14 mm. long with 22-24 segments which 

 from the third or fourth onward are about as long as broad; the outer bear dorsally 

 a pair of small erect median tubercles or small spines; P 2 is much longer than Pj or 

 P 3 , 13 mm. long, slender, with 20-21 segments which from the fourth onward are 

 between two and five tunes as long as broad, with prominently everted and spinous 

 distal ends; the pinnules from P 2 to P 6 are stiffened; the arms are about 90 mm. long. 



The stiffened and spiny early pinnules and the rather slender cirri give this 

 species an appearance suggesting a small Colobometra. 



Description. The centrodorsal is thin discoidal, with the bare polar area broad 

 and flat, 2 mm. in diameter. The cirrus sockets are arranged in a single crowded 

 marginal row. 



The cirri are XVI, 22-24, from 12 mm. to 14 mm. long. The first segment is 

 short and those following gradually increase in length to the third or fourth which, 

 with the remainder, is about as long as broad. The second and following segments 

 have the distal dorsal edge produced into a finely spinous transverse ridge which 

 gradually becomes crescentic in dorsal view, then V-shaped, on the tenth segment 



