A MONOGRAPH OF THE EXISTING CRINOIDS 311 



ensis are given. The characters assigned to bengalensis were drawn up from immature 

 individuals of reynaudi from the east coast of India, which were mistaken for bengalensis. 



HETEROMETRA ATER (A. H. Clark) 



Plate 26, Figures 109, 110 



Alecto savignii (part) J. Muller, Monatsb. Preuss. Auad. Wiss., 1841, p. 185; Archiv fur Naturg., 



1841, vol. 1, p. 144; Abh. Preuss. Akad. Wiss., 1841 (1843), p. 181. 

 Comatula (Alecto) savignii J. Muller, Abh. Preuss. Akad. Wiss., 1847 (1849), p. 257 (in part). 

 Antedon ludovici Berl. Mus., MS. A. H. Clark, Proc. TJ. S. Nat. Mus., vol. 40, 1911, p. 21. 

 Craspedometra ater A. H. Clark, Proc. U. S. Nat. Mus., vol. 40, 1911, p. 9 (northeastern Africa), 



p. 21 (description; Red Sea); vol. 43, 1912, p. 383 (<= Alecto savignii of J. Muller, in part), p. 384 



(original reference), p. 393 (synonymy; description; Red Sea); Crinoids of the Indian Ocean, 



1912, p. 119 (synonymy; Red Sea). 

 Heterometra ater A. H. Clark, Unstalked crinoids of the Siboga-Exped., 1918, p. 78 (in key; range). — 



Gislen, Kungl. Fysiogr. Siillsk. Handl., new ser., vol. 45, No. 11, 1934, pp. 22, 48.— A. H. 



Clark, John Murray Exped. 1933-34, Sci. Reports, vol. 4, No. 4, 1936, p. 99 (range), p. 104. 



Diagnostic features. — The brachials are distinctly wedge-shaped, with the ends 

 never quite parallel, and are not exceedingly short. The enlarged lower pinnules 

 are smooth, with the earlier segments keeled. The cirri are 30-33 mm. long and are 

 composed of 32-36 subequal segments all of which are half again as broad as long, the 

 outer bearing a small blunt median spine. The 14 arms are about 160 mm. long. 

 P 2 is half again as long as P! and much larger and stouter, 22 mm. long with 30 seg- 

 ments. P 3 is of the same length as P x and is much smaller and slenderer than P 2 . 



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

 convex, 4 mm. in diameter. The cirrus sockets are arranged in one and a partial 

 second crowded and irregular marginal row. 



The cirri are XXII, 32-36, from 30 mm. to 33 mm. in length, stout and not 

 tapering distally. The first segment is short, and those following gradually increase 

 in length to the fifth or sixth, which, with the remainder, is about half again as broad 

 as long. On the fifteenth or sixteenth the middle of the distal dorsal edge becomes 

 prominent, this prominence after one or two more segments becoming a prominent 

 rather high rounded carination of the entire mediodorsal line. Distally this carination 

 gradually narrows longitudinally so that on the last four or five segments preceding 

 the penultimate there is only a blunt median spine. The opposing spine is usually 

 rather longer and sharper than the spines on the preceding segments, terminal or sub- 

 terminal, directed obliquely forward, half as long as the width of the penultimate 

 segment. The terminal claw is somewhat longer than the penultimate segment, stout 

 and strongly curved basally but becoming straighter and slenderer in the distal 

 two-thirds. 



The radials are almost entirely concealed by the centrodorsal in the median line, 

 but their anterolateral portions are visible as very low broad triangles in the interradial 

 angles of the calyx. The IBri are very short, bandlike, five or six times as broad as 

 long, in close apposition laterally. The IBr 2 (axillaries) are very broadly pentagonal, 

 twice as broad as long. The IIBr series are 4 (3+4) and are well rounded dorsally. 

 The division series as far as P D are in lateral apposition, though they are not especially 

 flattened. The synarthrial tubercles are obsolete. 



