PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 739 



syzygial interval of only 2 muscular articulations, and by the much elongated distal 

 segments of the oral pinnules, which are very slender and almost hairlike. 



Description. — The centrodorsal is conical, in lateral view approximately an equi- 

 lateral triangle; the dorsal pole is thicldy set with somewhat elongated papillae. The 

 cirrus sockets are uniformly distributed over the surface, not crowded, somewhat 

 irregularly arranged, neither in definite columns nor rows. 



The cu-ri are about LX, 28-29 (usually the latter), 25 mm. long, and rather slender. 

 The first segment is twice as broad as long, the second is slightly longer than broad, 

 the third is about 4 times as long as the median width, and the fifth and si.xth arc the 

 longest, nearly or quite 6 times as long as the median width. The following segments 

 slowly decrease in length so tliat the last 10 to 15 are only slightly longer than broad. 

 The elongate proximal segments have somewhat, but not conspicuously, e.xpanded 

 ends; as the segments become shorter, the distal dorsal edge becomes prominent, in 

 distal view rising to an apex. On the short distal segments the dorsal profile gradually 

 rises from the pro.ximal to the distal end, which projects considerably beyond the base 

 of the segment succeeding so that in lateral view the dorsal profile is strongly serrate; 

 but the segments are not carinate dorsally. The opposing spine is long, prominent, 

 and erect, rising to a height about equal to the terminal width of the penultimate 

 segment. The terminal claw is stout basally, becoming more slender and more strongly 

 curved in the distal third. 



The distal edges of the radials extend shghtly beyond the rim of the centrodorsal; 

 the sides of the articular faces are well separated interradially so that the bases of the 

 IBr, are separated from each other by a distance about equal to their median length. 



The IBr, are short, 5 or 6 times as broad as long, with the lateral borders convergent 

 and slightly convex and the distal border nearly or quite straight, everted, and armed 

 with coarse denticulations or spines. The IBr2 (a.xillaries) are rhombic, about as long 

 as broad, with the anterior angle produced, the lateral angles extending well beyond 

 the anterolateral angles of the IBr,, and the two distal edges shghtly everted and 

 finely spinous. 



The 10 arms are slender, 85 mm. long. The first brachials are about twice as long 

 exteriorly as interiorly, the inner edges, which make an angle of about 120° with those of 

 the other first brachial of the same arm pair, are not quite in contact basally; the 

 distal edge is everted and finelj' spinous. The second brachials are much larger and 

 irregularly quadrate, with the distal edges everted and finely spinous. The first 

 syzygial pairs (composed of brachials 3+4) are slightly longer than the median width, 

 rather strongly constricted centrally with both the proximal and distal edges, especially 

 the latter, everted and finely spinous. The next 5 or 6 brachials are wedge-sliaped, 

 somewhat broader than long, coTistricted centralh", wnth the distal ends strongly 

 everted and spinous and the proximal ends more finely spinous. The following brachials 

 become much more obliquely wedge-shaped, longer than broad, with serrate or finelj- 

 spinous distal ends, the length of the brachials slowly increasing and the obliquitj' of 

 their ends slowly decreasing distally so that terminally the brachials are more than twice 

 as long as broad with only very slightly oblique distal ends. 



Syzj-gies occur between brachials 3+4, 9+10, 14 + 15, 18+19, and thence at 

 intervals of 2 muscular articulations. 



Pi is very slender, but stiffened, about 9 mm. long with 20 to 22 segments, of which 

 the first 3 are about as long as broad, the fourth is half again as long as broad, and the 



