PART 5 A MONOGRAPH OF THE EXISTING CKINOIDS 687 



broiid as long. At about the fifteenth the segments change their shape. The pro.ximal 

 portion of the dorsal edge ceases to be parallel with the ventral edge; it diverges from it. 

 The distal swelling occupies a greater portion of the dorsal edge. On the most distal 

 segments it comes to have the shape of a rounded keellike dorsal spine, two-thirds the 

 length of the segments. The opposing spine is strong, the terminal claw sharply curved. 

 The first 7 to 10 segments of the cirri are a dull yellow, the rest are lighter colored (in 

 alcohol) . 



The 10 arms are all incomplete. The longest remaining one is nearly complete; 

 it consists of 70 brachials and is about 55 mm. long. 



The radials are short in the midline. They are smooth, with concave distal edges. 

 The I Br, are not in apposition. Tliey are fairly deeply incised bj' the a.xillaries, and 

 are about four times as wide as the length in the midhne. The rhombic axillarj'- is as 

 \vide as long; the proximal edges are slightly, the distal strongly, concave; the proximal 

 angle is broadly rounded. The edges of both ossicles are roughened with fine spines. 



Syzygies occur between brachials 3+4, 9 + 10, 14 + 15 and thereafter, with few 

 exceptions, at intervals of three muscular articulations. The width at the first syzygy 

 is 1.0 mm. and the length from the IBr, to the second syzygy is 8.5 mm. 



The first brachial is short and incised by the second. The second is roughly tri- 

 angular, and about as long as broad. The brachials between the first and second 

 syzygial pairs are nearly rectangular, the more proximal wider than long, the distal 

 as long as broad. Immediately beyond the second syzygy the brachials are wedge- 

 shaped and longer than broad. Farther out on the arm they gradually become more 

 elongated ; the distal are rectangular and about as long as broad. A small triangular 

 area of the dorsal surface of the fifth to eighth brachials is raised into a spine-patch. 

 The distal edges of the brachials beyond the second syzygy are everted and produced 

 into a small number of low inconspicuous spines. 



The oral pinnules are long and flagellate, the genital and distal pinnules shorter 

 and more rigid. No Pj is quite complete. One which appears to be nearly so is of 21 

 segments and 9 mm. long. The first three or four segments are somewhat compressed 

 from side to side, and more massive than the remainder. The rest of the pinnule 

 tapers evenly, and is very flexible. The first and second segments are broader than 

 long, the third about as long as broad, the remainder longer than broad. The fifth 

 is twice, the fifteenth three times, as long as broad; the most distal segments are five 

 times as long as broad. Beyond the first three or four, which are compressed, the 

 segments are regularly cylindrical; their dorsal surfaces are rounded, not raised and 

 spiny; their distal edges are only slightly swollen. Pi and the other oral pinnules 

 are abundantly supplied with sacculi. 



Pj is of 21 segments and similar to Pi. P3 may be an oral pinnule, similar to Pi and 

 Pj, except that its proximal portion is somewhat hea^ner, or it may be the first genital 

 pinnule. 



P4, a genital pinnule, is of 13 segments and 6 mm. long. The gonad lies along 

 the fifth to eighth segments. The first two segments are short, the others longer 

 than broad. The third and fourth segments are twice, the fifth two and a half times, 

 the sixth and seventh three times as long as broad. The part of the pinnule bej'ond 

 the gonad is delicate and tapering, of segments about four times as long as broad. 

 There is no ambulacral furrow. P5 is similar to Ft except that the gonad lies along 

 the fourth to eighth segments and that it may or may not have an ambulacral furrow. 



