PART 5 A MOXOGRAPH OF THE EXISTtXG CRCNOIDS 133 



Description. — The centrodorsal is low hemispherical with a rather large flattened 

 dorsal pole from 1.5 to 2.5 mm. in diameter. The cirrus sockets are arranged in two or 

 three closely crowded and irregular marginal rows. 



The cirri are XXXV-LV, 13-17 (usually 16), from 6 to 13 mm. (the longest usu- 

 ally from 9 to 12 mm.) in length. In rare cases cini with 18 segments may be found. 

 The first segment is very short, about twice as broad as long, the third is about as long 

 as broad, and the fourth and fifth are the longest, about half again as long as broad; 

 the following very slowly decrease in length so that the penultimate is httle longer 

 than broad. In lateral view the cirri, slowly becoming laterally flattened, increase 

 gradually in ^ddth so that the outer portion may be nearly half again as broad as the 

 proximal. The opposing spine is small and inconspicuous, and occasionally absent. 

 The terminal claw is usually about as long as the last segment, and is stout and strongly 

 curved. 



The disk may be naked, but is usually more or less thickly studded with calcare- 

 ous nodules which are especially abundant along the ambulacral grooves, on and about 

 the anal tube, and in the inner angles of the interambulacral areas. 



The distal edges of the radials are even with the border of the centrodorsal in the 

 radial line, but are visible as low triangles with the distal apices shghtly separated in 

 the interradial angles. The IBri are short and more or less bandhke, four or five times 

 as broad as long, slightly depressed in the median line beneath the proximal angle of 

 the axillaries, with the lateral edges strongly convergent and not in contact basally 

 with their neighbors. The IBr2 (axillaries) are approximately triangular, nearlj' twice 

 as broad as long, with a slight posteriorly directed angle in the median portion of the 

 proximal edge, and with the lateral angles extending for some distance beyond the 

 anterolateral angles of the IBri. 



The 10 arms are up to 130 mm. in length. The first brachials are from two to 

 three times as long exteriorly as interiorly, with the distal border broadly V-shaped 

 and the inner sides of the two of each arm pair in contact basally, the portions be- 

 yond the point of contact lying usually in a straight line or making with each other a 

 very -wide angle. The second brachials are larger, irregularly quadrate, ^vith a more 

 or less developed posterior process incising the first. The first sj^zygial pairs (composed 

 of the third and fom"th brachials) are slightly longer interiorly than exteriorly, from a 

 third to half again as broad as long in the median line. The next three or four brachials 

 are slightly wedge-shaped, about twice as broad as the median length, after which the 

 brachials become triangular and about as long as broad, after the proximal fourth of 

 the arm very obliquely wedge-shaped, and then less and less obliquely wedge-shaped 

 and terminally about twice as long as broad wath only very slightly obhque ends. In 

 side view the brachials are not convex or flared at their distal ends. 



Syzygies occur normally between brachials 3-1-4, 9-|-10, and 14-f-15, and distally 

 at intervals of 3 muscular articulations, but there is often considerable irregularity in 

 individual specimens. 



In an unusually fine specimen from Kristineberg, Pi is 23 mm. long, with 49 seg- 

 ments, tapering evenly from a rather stout base to a long delicate and flagellate tip; 

 all the segments o.re subequal, somewhat longer than broad, the longest, in the middle 

 of the pinnule, being about half again as long as broad. The outer segments have 

 finely spinous distal ends. In five specimens from the vicinity of Bergen, Grieg found 



