542 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



EUMORPHOMETEA CONCINNA A. H. Clark* 



[See vol. 1, pi. 2. fig. 806, p. 378] 



Eumorphometra concinna A. H. CLARK, Journ. Washington Acad. Sci., vol. 5, 1915, No. 3, p. 81 

 (antarctic; range; nomen nttdum); Die Crinolden der Antarktis, 1915, p. 104 (new species col- 

 lected by the Gauss), p. 107 (in key to antarctic crinoids), p. 118 (detailed description; locality; 

 comparison with E. hirsuta), p. 168 (shallow water antarctic species; confined to the Gauss 

 quadrant and adjoining islands; range), p. 169 (relationships), p. 192 (further discussion), pi. 2, 

 figs. 2, 3; Unstalked crinoids of the Siboga-Exped., 1918, p. 232 (in key; range; references); 

 Smithsonian Misc. Coll., vol. 72, No. 7, 1921, pi. 2, fig. 25 (ambulacral deposits); Sci. Rep. 

 Australasian Antarctic Exped., 1911-14, ser. C, vol. 8, pt. 4, 1937, p. 5 (listed), p. 8 (in key). 

 JOHN, Proc. Linn. Soc. London, sess. 149, pt. 2, 1937, p. 86 (not taken by Discovery Investigations 

 vessels), p. 87 (brood pouch), p. 88; Discovery Reports, vol. 18, 1938, p. 123 (listed), p. 126 

 (viviparous), p. 127 (brood pouches), p. 133 (in key), p. 154 (comparison with E. aurora), p. 160 

 (description of brood pouches and embryos); Rep. B.A.N.Z. Antarctic Res. Exped. 1929-31, 

 ser. B, vol. 4, pt. 6, 1939, p. 203 (comparison with E. aurora). A. H. CLARK, Mem. Soc. Cubana 

 Hist. Nat., vol. 14, No. 2, 1940, p. 140. 



Diagnostic features. When the arms are about 30 mm. long, the cirri are about 

 XXX, with up to 25 segments and 7 mm. long; the IBr] has the distal side markedly 

 concave and the axillary is rhombic in shape; both these ossicles are distinctly spinous 

 at the edges; P, is very small, only about 2 mm. long, with 9 segments. 



Description. The centrodorsal is regularly conical, about as high as broad, with 

 the tip rounded. Its sides are nearly covered with about 30 cirrus sockets which are 

 roughly arranged in irregular columns and are entirely separated from each other. 



The cirri are about XXX, 20-23, 7 mm. long. The first two segments are short, 

 the third is nearly as long as broad, the fourth to sixth are nearly twice as long as the 

 median width, with expanded ends, and the following segments rapidly decrease in 

 length, becoming as long as broad on the eleventh and after the fifteenth slightly 

 broader than long. The longer earlier segments are centrally constricted, with rather 

 strongly expanded ends, this feature diminishing as the segments become shorter 

 distally. As the segments become shorter the dorsal surface becomes more and more 

 sharply rounded so that on the short distal segments the dorsal surface is sharply 

 carinate. 



The radials are relatively rather long, 3 or 4 times as broad as long in the median 

 line. The IBr series and brachials in general resemble those of Antedon mediterranea. 

 The IBi'i are about 3 times as broad as the lateral length, which is about twice the 

 median length; the distal outer angles are rounded off, the dorsal surface is covered with 

 fine spines, and the edges are bordered with very much longer spines. The IBr 2 

 (axillaries) are rhombic, slightly broader than long, with a very spinous dorsal surface 

 and spinous borders; the proximal lateral angles are cut away. The very numerous 

 fine spines thickly covering the dorsal surface of the elements of the IBr series are longer 

 and more prominent in the median line, which is slightly elevated into a low well-rounded 

 median carination. 



The 10 arms are 30 mm. long. The brachials are slender with expanded articula- 

 tions and rather strongly overlapping and spinous distal ends. 



Syzygies occur between brachials 3+4, 9+10, and 14 + 15, and distally at intervals 

 of 3 oblique muscular articulations. 



* See also Addenda (p. 837) under 1963 



