A MONOGRAPH OF THE EXISTING CRINOIDS 85 



only a conspicuous erect median tubercle. The opposing spine is erect, triangular, 

 arising from nearly or quite the entire dorsal surface of the petuiltimate segment, and 

 in height equal to about half the width of that segment. The terminal claw varies 

 from not quite so long as to longer than the penultimate segment, and is moderately 

 slender and rather strongly curved, especially in the proximal third. 



The radials extend only slightly beyond the rim of the centrodorsal in the mid- 

 radial line, but run well up in the interradial angles of the calyx ; they are entirely in 

 contact laterally. The IBri are about four tunes as broad as long, oblong with the 

 lateral edges and the proximal and distal borders parallel. The IBrj (axillaries) are 

 triangular with the lateral angles slightly truncated, and are nearly twice as broad as 

 long. Except in the central portion, the proximal border is more or less prominently 

 thickened and produced directly outward, plain, scalloped, or usually armed with a 

 few short spines or pointed tubercles. The lateral edges of the elements of the 

 IBr series are usually plain, but they may bear one or two rather long slender pointed 

 tubercles. 



The 10 arms are 55-60 mm. long in the largest specimens. The first brachials 

 are about four times as broad as the median length, and are from half again to twice 

 as long exteriorly as interiorly. The proximal border is straight, but the distal 

 border runs inward and downward at a considerable angle to the median line, then 

 turns and runs parallel to the proximal border to the inner anterolateral angle. The 

 inner sides are usually united in their proximal halves, but sometimes are merely in 

 contact basally. The second brachials are considerably larger than the first and are 

 irregularly quadrate. The first syzygial pair (composed of brachials 3+4) is about 

 as long as broad, and is very slightly longer interiorly than exteriorly. The next 

 three brachials are somewhat irregidarly oblong, at first twice as bi-oad as long but 

 becoming progressively longer, and those following almost immediately become 

 triangular, about as long as broad, with slightly produced and overlapping but 

 smooth distal ends. After the middle of the arm the brachials become very obliquely 

 wedge-shaped, and terminally they become elongate with somewhat conve.x sides. 



Syzygies occur between brachials 3+4, 12+13, 17 + 18, and 22+23, and distaUy 

 at intervals of from 2 to 6 (usually 4) muscular articulations. 



Pi is 5 mm. long with 8-10 (usually 9) segments of which the first is from two 

 and one-half to three times as broad as the median length, noticeably broadened, 

 with a prominent rounded or sometimes coarsely dentate carination. The second 

 segment, which tapers rapidly distally, is from half again to twice as broad proxi- 

 mally as distally, and nearly or quite twice as long as the distal width. The sides 

 converge strongly in the proximal half, then curve outward and become parallel in 

 the distal half or third. The broad basal portion is carinate dorsally. The third 

 segment is 2-5 (usuall}' about 4) times as long as broad, with parallel sides or slightly 

 broader pro.\imally than distally. The fourth segment is more or less, and usually 

 abruptly, shorter than the third, from 2 to 4 (usuall}' nearer the latter) times as long 

 as broad; rarely if the third segment is short the fourth is of the same length or some- 

 what longer. The segments following are similar to the fourth. The pimiule is 

 considerably stiffened, though not spinehke, moderately stout, evenly tapering from 

 the middle of the second segment to the tip, and shows a distinct prismatic crest, 



