A MONOGRAPH OF THE EXISTING CRINOIDS 245 



mally and narrowing, this transverse ridge finally, on from one to three segments 

 before the penultimate, becomes reduced to a small sharp median tubercle. The 

 opposing spine is large, sharp, and erect, triangular in lateral view, arising from 

 almost the entire dorsal surface of the penultimate segment, and in height equal to 

 from one-third to one-half the width of that segment. The terminal claw is longer 

 than the penultimate segment and is stout, sharply pointed, and strongly curved, 

 sometimes more strongly curved in the proximal third or half than distally. The 

 smallest cirri immediately about the dorsal pole of the centrodorsal are much shorter 

 than the peripheral cirri, only about one-third as long, and much more slender. They 

 are composed of 9-12 segments which become half again as long as broad distally. 

 The segments are somewhat constricted centrally with prominent ends, and the 

 dorsal processes are very slight or even entirely absent. 



The radials are short, from 8 to 10 times as broad as long in the median line, 

 with the distal edge slightly concave and the lateral edges free. The IBr! are short, 

 about three tunes as broad as long, approximately oblong but with the proximal 

 border slightly convex. There is a small ventrolateral tubercle in the middle or 

 in the distal half of the lateral borders. The IBr 2 (axillaries) are short, twice as 

 broad as long, triangular with the lateral angles broadly truncated so that the lateral 

 sides are about half as long as the sides of the IBr 1; or shorter. These lateral sides 

 are produced into a slight flangelike process. There is a low and broad synarthrial 

 tubercle occupying the proximal third or half of the midline of the IBr 2 and the 

 entire midline of the IBrj on which it diminishes hi height proximally. 



The 10 arms are 40 mm. long. The first brachials are wedge-shaped, about twice 

 as long exteriorly as ulteriorly. Their interior sides are usually united for the proximal 

 half, the distal halves diverging at approximately a right angle. The exterior sides 

 are produced into a usually narrow flange the outer edge of which is straight. The 

 second brachials are of about the same size as the first, but are more obliquely wedge- 

 shaped. The first syzygial pair (composed of brachials 3+4) is longer interiorly than 

 exteriorly, and is about twice as broad as the median length. The epizygal is approxi- 

 mately oblong, and the hypozygal is wedge-shaped. The next four brachials are 

 oblong or very slightly wedge-shaped, about four times as broad as the median length. 

 After the second syzygy the brachials are very obliquely wedge-shaped, almost tri- 

 angular, half again as broad as long, with strongly produced, slightly everted, finely 

 spinous distal ends. After the proximal third of the arm the brachials lose the strong 

 eversion of the distal ends and become slowly and gradually longer so that the distal 

 brachials are about as long as broad and the terminal are longer than broad. 



Syzygies occur between brachials 3+4, 9+10, and 14+15, distally at intervals 

 of 4 and subterminally at intervals of 5 + 7 muscular articulations. 



PI is 3.3 mm. long with 13 segments and tapers from a moderately stout base to 

 a delicate tip. It is rather strongly prismatic, though the prismatic ridge is rounded. 

 The first segment is short, the third is about as long as broad, and the distal are about 

 twice as long as broad, becoming longer subterminally. The second-fourth segments 

 are strongly carinate, the carinate processes being highest on the second and third. 

 The segments in the distal half have very finely spinous distal ends, but these are not 

 conspicuous. P 2 is 3.8 mm. long, slightly stouter than P, basally and, like it, tapering 

 gradually to the tip. It is composed of 13 segments of which the first is almost tri- 



