A MONOGRAPH OF THE EXISTING CRINOIDS 555 



is somewhat longer than the penultimate segment, moderateh^ stout, and rather 

 strongly curved basally, becoming more slender and less curved distally. 



The segment upon which the distal dorsal edge first begins to bo prominent is in 

 reality a transition segment, though in most specimens it is not particularly marked 

 as such. The short distal segments are, however, always more highly polished than 

 the more proximal. The transition segment, when distinguishable, is usually about 

 the twelfth. 



The ends of the basal rays are visible as prominent tubercles in the intcrradial 

 angles of the caly.x. 



The radials arc concealed by the centrodorsal in the median line, but extend 

 upward in the interradial angles as far as the distal fourth of the IBri in the form of a 

 broad triangle over the ends of the basal raj's. The IBri are short and broad with 

 the proximal border convex due to the interradial triangles formed by the radials, 

 four or five times as broad as the median length; the lateral edges are very short, 

 meeting above the ends of the radials but diverging in their distal half at approxi- 

 mately a right angle, or forming a U-shaped gap. The IBra (a.xillaries) are broadly 

 pentagonal or almost triangular, rather more than twice as long as the IBrj, about 

 twice as broad as long, not in lateral contact. The IIBr series are 4 (3 + 4), broad, 

 moderately rounded dorsally, exposing between them a strip of perisome usually 

 equal to about one-third of their own width. The IIIBr series are 4 (3 + 4), usually 

 nearly or quite all present. The IVBr series are 4 (3 + 4), but rarely present. The 

 division series are all somewhat massive in structure. 



The arms are 25-49 (usually about 40) in number, from 100 to 200 mm. in length. 

 The first brachials are wedge-shaped, almost entirely united interiorly, about twice 

 as broad as the exterior length. The second brachials are similar in size and shape, 

 but are not in contact interiorly. The first syzygial pair (composed of brachials 

 3 + 4) is not quite so long as broad. The next 4 brachials are oblong, from two to two 

 and one-half times as broad as long, and those succeeding rapidly become wedge- 

 shaped and after the twelfth triangular and half again as broad as long. At the end 

 of the first third of the arm the brachials gradually become wedge-shaped again and 

 decrease in length, in the distal half of the arm being almost or quite oblong, three or 

 four times as broad as long. After the fourth the brachials develop overlapping and 

 finely spinous distal ends wliich become very prominent in the distal half of the arm. 

 The arms usually increase somewhat in width up to the twelfth brachial, thence 

 gradually tapering distally. 



Syzygies occur between brachials 3 + 4, again from between brachials 14+15 to 

 between brachials 21 + 22, and distally at intervals of 4 muscular articulations. 



The disk is very large, from 30 to 42 mm. in diameter, and is naked. The anal 

 tube is large, central, or subcentral. The mouth is submarginal, variable in position. 



Pd is from 35 to 40 mm. in length, very stout basally but tapering rather rapidly 

 as far as the ventral surface of the disk, then remaining of uniform width, moderately 

 slender, though distinctly stouter than usual in this genus, and relatively stouter than 

 in C. bennetti. It is composed of from GO to 65 segments, all of which are somewhat 

 broader than long, the enlarged basal segments being the shortest. The terminal 

 comb is very long with 16-18 teeth which are small, vertically oval or almost circular, 



