A MONOGRAPH OF THE EXISTING CRINOIDS 137 



Unstalked crinoids of the Siboga Exped., 1918, p. 63 (in key; range), p. 64 (synonymy; notes; 

 stations 49a, 294), pp. 271, 275 (listed).— F. W. Clarke and Wheeler, U. S. Geol. Surv. 

 Prof. Pap. 124, 1922, p. 17 (inorganic constituents of the skeleton). — Gislen Kungl. Fysiogr. 

 Sallsk. Handl., new ser., vol. 45, No. 11, 1934, pp. 21, 27. 



Diagnostic features. — The arms are 20-27 in number, the IIBr series being 4(3+4), 

 180 mm. long in fully grown individuals, and the cirri are composed of 15-19 (usually 

 17-19) segments of which the longest are twice as long as the median width and the 

 outermost are half again as long as broad. In its general appearance this species 

 most nearly resembles C. rubroflava, but the greater number of arms and the longer 

 cirri, which are composed of longer segments, easily distinguish it from that form. 

 In color it appears to be usually olive-green or brown, but occasionally red and yellow 

 like C. rubroflava. 



Description. — The centrodorsal is thin discoidal with a broad moderately concave 

 polar area 5-8 mm. in diameter marked in the center by a shallow rounded pit. The 

 cirrus sockets are arranged in two closely crowded irregular marginal rows. 



The cirri are XXVII, 15-18 (usually 17), 22 mm. long. The first segment is 

 about twice as broad as long, the second is not quite so long as broad, the third is half 

 again as long as the median width, the fourth and fifth are twice as long as the median 

 width, and those following gradually become very slightly shorter so that the terminal 

 segments are half again as long as broad. The dorsal and ventral profiles of the longer 

 proximal segments, especially the former, are rather strongly concave, this feature 

 gradually dying away distally. The lateral profiles of these longer proximal segments 

 are very strongly concave, this character gradually becoming less marked but persist- 

 ing to the end of the cirri. The penultimate segment is about one-third again as long 

 as broad. The opposing spine is terminal, small and inconspicuous. The terminal 

 claw is half again as long as the penultimate segment, slender and slightly curved. 



The radials are only just visible in the interradial angles of the calyx. The IBri 

 are oblong, very short and bandlike. The IBr 2 (axillaries) are triangular, nearly 

 three times as broad as long. The IBr series are well separated laterally. The IIBr 

 series are 4(3 + 4). The IIBri are interiorly united for the proximal half or two-thirds, 

 their interior sides diverging from that point so as to make a right angle with each other. 

 The IIIBr series, when present, are 2, always developed interiorly in 1, 2, 2, 1 order. 

 The synarthrial tubercles are prominent and sharp. 



The arms are 20-27 in number, 180 mm. in length. The first brachials are 

 wedge-shaped, about twice as broad as long exteriorly, interiorly united for about the 

 proximal two-thirds. The second brachials are of about the same size but more ob- 

 liquely wedge-shaped. The first syzygial pair (composed of brachials 3+4) is slightly 

 longer interiorly than exteriorly, about twice as broad as the median length. The 

 next five brachials are oblong or slightly wedge-shaped, two to three times as broad as 

 long, and those following become triangular and as long as broad, distally obliquely 

 wedge-shaped, and terminally longer than broad. The distal borders of the tenth 

 and following brachials are moderately overlapping and finely spinous. 



Syzygies occur between brachials 3 + 4, again from between brachials 19 + 20 to 

 between brachials 36+37 (usually about brachials 27 + 28), and distally at intervals 

 of 8-16 (usually 10 or 11) muscular articulations. 



208244—40 10 



