A MONOGRAPH OF THE EXISTING CRINOIDS 85 



The cirri are XVII-L (usually XXXV-XLII), 30-70 (usually 45-55), 25-55 

 (usually 35-45) mm. long, long and stout. The longest segments, in the proximal 

 half of the cirri, vary from slightly broader than long to slightly longer than broad, 

 being usually about as long as broad, and those beyond the twelfth-twentieth, which is 

 usually a more or less marked transition segment, are much broader than long. The 

 segments beyond the transition segment bear dorsal spines with glassy tips, which are 

 commonly blunt, though well marked, but may be either small or prominent and 

 conspicuous. The opposing spine is strong and sharp, directed obliquely distally, 

 usually, but not always, more conspicuous than the dorsal spines preceding; its height 

 is equal to about half the width of the penultimate segment. The terminal claw is 

 usually half again as long as the penultimate segment and is moderately curved. 



The distal edge of the radials may be just visible beyond the rim of the centro- 

 dorsal, or the radials may be almost completely concealed, only their anterolateral 

 angles being visible in the interradial angles. The IBr x are very short, six to eight 

 times as broad as long, and are either entirely free laterally or just in contact basally. 

 The IIBr series, IIIBr series, and IVBr series are 4(3+4), rarely or exceptionally 2, 

 most frequently the IIIBr series. The IVBr series are usually developed internally 

 in reference to the IIIBr series. The postradial series are strongly convex dorsally 

 and are more or less compressed laterally, often having a fairly distinct ventrolateral 

 rim. 



The arms are 40-100 (usually 50-90) in number and are 60-150 (averaging about 

 110) mm. long. They are smooth, strongly convex dorsally, and laterally com- 

 pressed. The brachials are at first short and oblong, then short and almost or quite 

 triangular, and later short wedge-shaped, becoming squarish toward the arm tips. 



Syzygies occur between brachials 3+4, again from between brachials 23 + 24 to 

 between brachials 39 + 40 and from between brachials 42 + 43 to between brachials 

 56 + 57, and distally at intervals of 8-20 (usually 11-15) muscular articulations. 

 Sometimes there is an additional syzygy from between brachials 8 + 9 to between 

 brachials 13 + 14. 



The proximal pinnules are usually exceedingly long with broad and slightly 

 keeled basal segments, more rarely of moderate length. 



P D and P P are long and stout, P, being often rather longer than P„. P D may 

 reach 32 mm. in length. P D and P P are composed of 40-60 (rarely as few as 25) 

 segments of which the basal are broad, but not especially distinguished, and those 

 following diminish in size and gradually develop a projection of the dorsal edge at the 

 distal end that disappears in the smaller terminal segments. P! is more or less smaller 

 than P„ 18-25 mm. long with 25-56 (usually 30-50) segments of which the basal are 

 broad, about as long as broad, and the distal are half again as long as broad. The 

 proximal portion of the pinnule up to the fifth segment tapers slightly, the pinnule 

 from this point onward becoming more rapidly flagellate. P 2 is usually more or less 

 considerably smaller than P 1; but it may be of the same size or even slightly larger. 

 It is 20-25 mm. long, with 37-56 segments of which the basal are a little flattened. 

 P 3 resembles P, and P 2 but is shorter and smaller, up to 20 mm. long with 25-38 seg- 

 ments. P 4 resembles P 3 but is smaller and shorter, up to 13 mm. long with 26 seg- 

 ments. P 6 is 10 mm. long with 24 segments, and Pi is 8 mm. long with 15 segments. 

 The distal pinnules are 8 mm. long with about 20 segments. 



