172 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



EUDIOCRINUS OBNATUS A. H. Clark 



PLATE 11, FIGURE 40; PLATE 12, FIGURE 47 



[See also vol. 1, pt. 1, fig. 250 (centrodorsal), p. 253, figs. 465, 466 (centrodorsal) , p. 359; pt. 2, 

 figs. 29-31 (radial pentagon), p. 20, fig. 190 (side view), p. Ill, figs. 436-439 (pinnule tips), 

 p. 261, fig. 712 (disk), p. 346.] 



Eudiocrinus ornatus A. H. CLAEK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 76 (nomen nudum; 

 arms and pinnules compared with those of E. minor); Proc. U. S. Nat. Mus., vol. 36, 1909, 

 p. 633 (1404'30" N., 9351'00" E.; description); Crinoids of the Indian Ocean, 1912, p. 99 

 (synonymy; detailed description; localities), fig. 4, p. 100; Amer. Journ. Sci., vol. 40, 1915, 

 p. 62 (listed); Unstalked crinoids of the Siboga-Exped., 1918, p. 65 (in key; range), p. 70 (syn- 

 onymy; detailed description; Sta. 294; possibly a variety of E. indivisus), p. 275 (listed), pi. 17, 

 fig. 29; Rec. Indian Mus., vol. 34, pt. 4, 1932, p. 551 (listed), p. 554 (Investigator station 387; 

 notes), p. 556 (compared with E. philenor). 



Eudiocrinus minor A. H. CLARK, Proc. Biol. Soc. Washington, vol. 22, 1909, p. 75 (description; 

 Andaman Islands); Crinoids of the Indian Ocean, 1912, p. 102 (synonymy; detailed description; 

 Andaman Islands), fig. 5, p. 103; Amer. Journ. Sci., vol. 40, 1915, p. 62 (listed); Unstalked 

 crinoids of the Siboga-Exped., 1918, p. 65, footnote (synonym of E. ornatus). 



Diagnostic features. Resembling E. indivisus, but the brachials have very 

 prominent, everted, and overlapping distal ends, giving the animal a curiously ornate 

 appearance. 



Description. The centrodorsal is a thin disk, with the bare polar area flat, 2.5 

 mm. in diameter. The cirrus sockets are arranged in a single marginal row. 



The cirri are XVIII, 17-18, 20 mm. long. The first segment is twice as broad 

 as long, the second is nearly or quite as long as broad, the third fifth are twice as 

 long as the proximal diameter, the sixth is slightly shorter, a more or less marked 

 transition segment, and the following gradually decrease in length so that the ter- 

 minal segments are only slightly longer than broad. The penultimate segment is 

 about as long as broad. The third-sixth segments are very strongly constricted 

 centrally with the distal edge all around produced, except on the dorsal side; from 

 the seventh onward both these features become less marked, and the cirrus becomes 

 somewhat compressed laterally. There are no dorsal processes. The opposing spine 

 is sharp, prominent, arising from the entire dorsal surface of the penultimate segment, 

 equal to about one-half of the lateral width of that segment in height. The ter- 

 minal claw is equal in length to the penultimate segment, and is stout and strongly 

 curved. 



The ends of the basal rays are visible as small tubercles in the angles of the calyx. 



The distal borders of the radials project slightly beyond the rim of the centro- 

 dorsal, and are slightly concave. The IBr : and IBr 2 form a syzygial pair, which is 

 oblong, from one-third to one-half again as broad as long, with the lateral edges 

 straight, barely in apposition basally, and the ventrolateral border slightly produced. 



The five arms are 85 mm. long. The first brachial is oblong, about three times 

 as broad as long, the second is slightly wedge-shaped, about the same size, and the 

 first syzygial pan- (composed of brachials 3+4) is slightly longer on one side than on 

 the other, half again as broad as the median length. The next three brachials are 

 approximately oblong, two and one-half times as broad as long, and those following 

 becoming triangular, as broad as long, and after the proximal fourth of the arm 

 wedge-shaped, as long as broad, and in the terminal portion somewhat longer. The 



