A MONOGRAPH OF THE EXISTING CRINOIDS 217 



The IBr, are oblong, rounded dorsally and laterally, about three times as broad 

 as long, widely separated laterally. The IBrj (axillaries) are pentagonal, from one- 

 third to one-half again as broad as long, with the lateral edges, which are about as 

 long as those of the IBri, diverging distally. The IIBr series are 4 (3 + 4). The 

 IIIBr series are 3 (2 + 3). The division series are separated by a distance about equal 

 to the width of the IIBr series. If all of the IIIBr series are not present, those most 

 frequently absent are the ones on the outer sides of the IBr series, so that there is 

 an approximation to a 1, 2, 2, 1 arrangement. 



Arms 24-31, about 200 mm. long. The first brachials are wedge-shaped, rather 

 large, not quite half again as broad as the exterior length, almost entirely united 

 interiorly. The first syzygial pair (formed of brachials 2 + 3) is not quite so long as 

 broad. The next 4 brachials are oblong, about twice as broad as long, the following 

 becommg wedge-shaped and after 3 or 4 triangular, and about as long as broad. In 

 the terminal portion of the arms the brachials become wedge-shaped and nearly or 

 quite twice as long as broad. The distal edges of the brachials project slightly and 

 are beset with fine spines. 



Syzygies occur between brachials 2 + 3, again from between brachials 14 + 15 to 

 22 + 23 (usually in the vicinity of the eighteenth brachial), and distally at intervals 

 of 3 muscular articulations. 



The mouth is marginal and radial. The anal tube is central. The disk is naked, 

 about 30 mm. in diameter. Side plates are developed along the brachial and pinnule 

 ambulacra. 



Pd is from 30 to 35 mm. in length, stout, much stouter than the succeeding 

 pinnules, but tapering evenly to a slender and flagellate tip. It consists of 40-45 

 segments, all of which are about as long as broad. A slight prominence is visible 

 on the dorsal side of the distal edge of the second segment which rapidly becomes 

 larger and increases in width on those succeeding, after about the seventh taking 

 the form of a strong, coarsely spinous eversion of the dorsal edge; this disappears 

 near the proximal part of the distal comb. The comb arises somewhat abruptly. 

 It is composed of 14 teeth, of which the first is low and triangular, the second is 

 oblong or sUghtly trapezoidal, usually slightly broader basally than high, and those 

 following become more obliquely trapezoidal and relatively somewhat higher, the 

 terminal teeth being truncated triangular. The more proximal teeth are not equal 

 in height to more than three-quarters of the width of the segments that bear them, 

 but the later teeth, owing to the distal tapering of the pinnule, become about equal 

 to the width. Pp is about 25 mm. long, considerably less stout than Pd but otherwise 

 similar to it. 



Pi is about 20 mm. long, much less stout than Pp, though similar to it. P2 

 and the following pinnules are slender and delicate, about 10 mm. long. P2 bears a 

 comb distally, but the following pinnules are without combs. P2, P3, and P4 and 

 the corresponding pinnules on the inner side of the arms have the first 2 segments 

 disproportionately large and produced dorsally into large carinate processes. The 

 distal pinnules are slender, about 12 mm. long, composed of about 25 segments, of 

 which the first is over twice as broad as long, the second is about as long as broad, 

 97298—31 1.5 



