A MONOGRAPH OF THE EXISTING CRINOIDS 119 



COMATELLA DECORA A. H. Clark 



Comatula paucicirra A. H. Clark, Proc. U. S. Nat. Mus., vol. 34, 1908, p. 317 (Japan); Crinoids 

 of the Indian Ocean, 1912, p. 71 (identity). 



Comatella decora A. H. Clakk, Crinoids of the Indian Ocean, 1912, p. 71 (synonymy; detailed de- 

 scription; southern Japan; ?Ki Is. [latter is Palaeocomatella difficilis]); Journ. Washington 

 Acad. Sci., vol. 5, No. 6, 1915, p. 214 (southern Japanese species; range and its significance); 

 Unstalked Crinoids of the Siboga E.xped., 1918, p. 4 (in key; range). — Glsl^n, Nova Acta 

 reg. Soc. sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, p. 15 (compared with C. brachycirra) ; 

 Vidensk. Medd. fra Dansk naturh. Foren., vol. 83, 1927, p. 7 (Mortensen's Sta. 9; notes); 

 figs. 1, 2, p. 15. 



Diagnostic features. — The cirri are 15 mm. long and rather stout, but consist of 

 only 12-13 segments, of which the fourth and fifth are rather over t\vice as long as 

 broad; there are 19 arms about 90 mm. long; Pi-Pe bear combs; Pi is composed of 

 about 40 segments and its comb has 12 teeth. 



Description. — The centrodorsal is large, thick discoidal, with the large bare polar 

 area flat, obscurely pitted about the periphery. 



The cii'ri are XX, 12-13, 15 mm., long; the first segment is very short, the second 

 is half again as long as broad, the third is twice as long as broad, the fourth and fifth 

 are rather over twice as long as broad, the fifth is slightly longer than the fourth, 

 and the sixth is about twice as long as broad; the following decrease gradually in 

 length so that the last two or three before the penultimate are about as long as 

 broad, and the penultimate is about half again as broad as long. From the sixth 

 onward the distal dorsal edge of the segments is slightly everted, forming a low 

 crescent-shaped or shallow V-shaped ridge across the distal end of the segment 

 which appears as a low subterminal spine in lateral view. The dorsal surface of the 

 seventh and following segments has a slight median carination. The opposing spine 

 is triangular, blunt, arising from the entire surface of the penultimate segment, the 

 apex subterminal to subcentral, low, equal to about one-third of the distal diameter 

 of the penultimate segment in height. The terminal claw is twice as long as the 

 penultimate segment, strongly curved basally but becoming straighter distally. 



The ends of the basal rays are visible as rather large flattened rhombic tuber- 

 cles in the angles of the calyx. 



The radials are concealed in the median line, but interradially form a triangle over 

 the ends of the basal rays; they are slightly separated distally. The IBri are trape- 

 zoidal, short, over three times as broad as long, strongly rounded dorsally, separated 

 basally by the distal divergence of the radials, the sides of adjacent IBri diverging at 

 a very obtuse angle. The IBra (axillaries) are broadly pentagonal, about half again 

 as broad as long, the lateral edges about as long as those of the IBr, with which they 

 form an obtuse angle, the lateral edges of the IBra on adjacent rays being practically 

 parallel. A broad strip of perisome, in width about equal to one-third of the diam- 

 eter of the IBr series, is visible between them (and similarly between the IIBr series), 

 but it does not extend dorsally beyond their ventral edge. The IIBr series are 2 

 (8 are present and 2 absent in the type). The IIBr, are united for their proximal 

 two-thirds, the distal third of the mner border of the two in each pair diverging in 

 almost a straight line. The IIIBr are 2, only present in one instance, on the outer 

 side of a derivative from a IBr series. 



