474 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



KEY TO THE SPECIES OF ERYTHROMETRA 



[See note by A.M.C., p. 475] 



a 1 . Cirri with 36-39 segments, 18mm. long; arms 60 mm. long (Moluccas and Kei Is.;239-245 meters). 



australis (p. 474) 



a 2 . Cirri with 30 segments, 10-11 mm. long; arms 25-35 mm. long (southern Japan; 100 [?95]-274 

 meters) rubra (p. 475) 



ERYTHROMETRA AUSTRALIS A. H. Clark 



[See vol. 1, pt. 2, fig. 773, p. 362] 



Erythrometra auslralis A. H. CLARK, Unstalked crinoids of the Si&oi/a-Exped., 1918, p. 235 (in key; 

 range; detailed description; Albatross sta. 5617). 



Diagnostic features. When the arms are 60 mm. long, the cirri have 36-39 seg- 

 ments. 



Description. The centrodorsal is hemispherical, the small bare dorsal pole covered 

 with closely set rounded tubercles. 



The cirri are about XXX, 36-39, 18 mm. long, decreasing to 4 mm. long, with 

 about 15 segments near the dorsal pole of the centrodorsal. In the long peripheral 

 cirri the first two segments are more than twice as broad as long, the third is slightly 

 broader than long, the fourth is from a third to a half again as long as broad, the fifth 

 and sixth are about twice as long as broad, and the following gradually decrease in 

 length to the fourteenth, which is about as long as broad, and still further to the last 

 dozen or so, which are about twice as broad as long. The longer earlier segments are 

 rather strongly constricted centrally, with prominent ends. The distal dorsal border 

 of the proximal segments is prominent, and as the segments become shorter they grad- 

 ually develop a prominent median carination, the crest of which is convex in profile. 



The radials extend slightly beyond the rim of the centrodorsal ; their distal border 

 is abruptly everted, smooth or more or less tubercular. The IBi'i are approximately 

 oblong, between 3 and 4 times as broad as long, with the proximal and distal edges 

 prominently everted and the lateral edges bearing from 4 to 6 long blunt tubercles. 

 The IBr 2 (axillaries) are rhombic, not quite twice as broad as long, with the proximal 

 and distal edges everted and the lateral angles produced into a ventrolateral process, 

 or bearing 2 long blunt tubercles resembling those on the lateral borders of the IBri. 

 Usually the sides of adjacent IB^ diverge at an angle of about 60, and the lateral 

 angles of the axillaries nearly meet above the gap thus formed. 



The 10 arms are about 60 mm. long. The first brachials are short, twice as long 

 exteriorly as interiorly, the median length approximately the same as the inner; the 

 inner edges are in apposition, and the outer bear a rather broad thin ventrolateral 

 process, and at the distal angle a tubercle. The proximal and the outer half of the distal 

 edges are thickened and everted. The second brachials are irregularly quadrate, twice 

 as broad as long, with the proximal border slightly everted ; the proximal inner and outer 

 angles usually bear a tubercle. The first syzygial pair (composed of the third and fourth 

 brachials) is slightly longer interiorly than exteriorly, and half again as broad as the 

 median length. The next two brachials are roughly oblong, and those following become 

 triangular, about as long as broad, and after the basal third of the arm wedge-shaped 

 and elongate distally. The distal edges of the brachials are rather prominent and finely 

 spinous; their dorsal surface is longitudinally striate. 



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

 of 2 muscular articulations. 



