A MONOGRAPH OF THE EXISTING CRINOIDS 425 



1912, pp. 34, 40, 41 (identity of previous records), p. 135 (synonymy; localities; notes on the 

 type specimen). H. L. CLARK, Spolia Zeylanica, vol. 10, pt. 37, 1915, p. 93 (occurs at Ceylon). 



Stephanometra sp. A. H. CLARK, Bull. Mus. Hist. Nat., Paris, 1911, p. 252 (New Caledonia; notes). 



Stepkanometra stypacantha H. L. CLARK, Carnegie Inst. Washington Publ. 212, 1915, p. 103 (descrip- 

 tion; Mer). A. H. CLARK, Unstalked crinoids of the iSifcoj/a-Exped., 1918, p. 94, footnote 2 

 (synonym of S. spicata). H. L. CLARK, The echinoderm fauna of Torres Strait, 1921, p. 8 

 (collected by the Carnegie Exped., 1913), p. 22 (Mer; notes; color in life), pp. 192 ff. (range in 

 Australia), pi. 22, fig. 4, pi. 36, figs. 3, a-e. 



Diagnostic features. The outer cirrus segments are wholly without dorsal proc- 

 esses, being merely more or less sharply carinate in the middorsal line; P! is flexible, 

 flagellate, delicate, and slender, much smaller and weaker than P 3 ; P 2 and P 3 are much 

 enlarged, stiffened, and spinelike, P 3 being smaller than P 2 though otherwise similar 

 to it; P 4 is small and weak like the pinnules following; there are 14-33 (usually about 

 30) arms 70-120 (most commonly about 100) mm. long; and the cirri have 18-28 

 (usually 20-25) segments. 



Description. The centrodorsal is discoidal, usually rather thin though sometimes 

 thick, with strongly sloping sides and a small concave dorsal pole, more rarely low 

 hemispherical, with an approximately flat, small dorsal pole. The cirrus sockets are 

 arranged in from one and a partial second to three or more, but usually in two, irregu- 

 larly alternating marginal rows. 



The cirri are XXV-LII (usually XXV-XXXV), 18-28 (usually 20-25), 15 to 

 30 mm. (usually 20-25 mm.) long. The basal segments are short, and those following 

 gradually increase in length to the fourth or fifth, which with a few of those succeeding 

 are usually from one-third to one-half again as long as broad but vary from slightly 

 broader than long to twice as long as broad. The following segments gradually 

 decrease in length so that the distal are usually somewhat broader than long, though 

 they may be as long as broad, or even slightly longer than broad. The short outer 

 segments are rather strongly compressed laterally and bear a more or less well developed 

 keel in the middorsal line. The opposing spine is prominent, subterminal, and di- 

 rected obliquely forward. The terminal claw is slightly longer than the penultimate 

 segment and is stout and rather strongly curved. 



The radials are wholly concealed, or their distal ends are just visible beyond the 

 rim of the centrodorsal. The anterolateral angles of adjacent radials are separated 

 by a notch. The IBrj are short, oblong, rather strongly convex dorsally, and quite 

 free laterally. The IBr 2 (axillaries) are broadly pentagonal and are from about half 

 again to more than twice as long as the IBri. The IIBr, IIIBr, and IVBr series are 2. 

 The IIIBr series are usually developed only on the outer sides of the postradial series 

 so that typically each postradial series bears six arms arranged in 2, 1, 1, 2 order. 

 The ossicles immediately following each axillary are almost completely united interi- 

 orly. The division series are well separated, rather narrow, and rather strongly 

 convex. More or less well developed synarthrial tubercles are present. The ventro- 

 lateral borders of all the ossicles from the IBr! to the second brachials inclusive bear 

 usually small irregular projections toward the ventral side; but they may be produced 

 into prominent, though narrow, fiangelike extensions. 



The arms are 14-33 (usually about 30) in number and are 70 to 120 mm. (most 

 commonly about 100 mm.) in length. They consist of about 120-150 brachials. The 

 first two brachials are wedge-shaped, the second having more oblique ends than the 



208244 11 28 



