PART 5 A MONOGRAPH OF THE EXISTING CRENOIDS 59 



Cirri XXIV, 13-16, 10 mm. long, recalling those of Antedon petasus but smoother 

 dorsally and more slender proximally; first segment short, second slightly longer, third 

 as long as broad or slightly longer than broad, fourth slightly longer than the third, 

 fifth and sixth the longest, just under twice as long as the proximal width, the following 

 gradually becoming laterally compressed and, though remaining actually of the same 

 length, increasing in lateral diameter and becoming therefore relatively shorter so that 

 the last four before the penultimate are only slightly longer than broad; in the proximal 

 portion the cirri are in lateral view slender, and rounded in cross section ; in the distal 

 half they become strongly compressed and in lateral view about twice as broad as in 

 the proximal half; there are no dorsal processes; opposing spine short, subterminal to 

 submedian, its base involving only a small part of the dorsal surface of the segment ; in 

 height scarcely one-third the distal diameter of the penultimate segment, directed 

 obliquely forward; terminal claw somewhat longer than the penultimate segment, stout 

 and strongly curved. 



Radials just visible beyond the rim of the centrodorsal; their distal angles are 

 separated. 



IB^ short, about four times as broad as long in the median line, trapezoidal, 

 widely separated interradially, their sides making an angle of nearly 120 with those 

 of their neighbors; IBr 2 broadly pentagonal; the anterior angle measures approxi- 

 mately 90; the lateral edges are nearly as long as those of the IBr] and make with 

 them an angle of about 120; the synarthrial tubercles are rather prominent, and the 

 elevation is continued somewhat anteriorly onto the axillary. 



Arms 10, about 90 mm. long; first brachial short, over twice as broad as long 

 exteriorly, the exterior length being rather more than twice as great as the interior; 

 the inner edges of adjacent first brachials are united basally, but distally diverge at a 

 very broadly obtuse angle; second brachial about twice as large as the first, irregularly 

 quadrate; first syzygial pair (composed of the third and fourth brachials) nearly twice 

 as long interiorly as exteriorly, the inequality falling chiefly in the hypozygal, twice 

 as broad as long in the median line; next four brachials slightly wedge-shaped, twice as 

 broad as the greater length, the following become triangular, about as long as broad, 

 and after the proximal quarter of the arm wedge-shaped, about as long as broad, and 

 terminally somewhat longer. 



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

 of three muscular articulations. The width at the first syzygy is 1.2 mm. and the 

 length from the beginning of the division series to the second syzygy is 7.0 mm. 



PI is 5.5 mm. long, composed of 15 segments, of which the first is short, the second 

 longer, the third nearly as long as broad, the fourth slightly longer than broad, and 

 the seventh and following about twice as long as broad; the pinnule is small and slender, 

 and tapers evenly from the base to a slender and delicate tip ; there is a slight swelling 

 on the distal edge of the second and third segments; P 2 7.5 mm. long, with 16 segments, 

 resembling P, but proportionately stouter; the distal edges of the third and following 

 segments are slightly produced and finely spinous; as in P! the dorsal edge of the second 

 and third segments is slightly thickened; P 3 from 12 te 13 mm. long with 22 seg- 

 ments, resembling P 2 but proportionately stouter; P 4 from 5.0 to 5.5 mm. long 

 with 14 segments, similar in size to P 2 but with the distal segments very slightly shorter; 

 P 6 6 mm. long with 15 segments, slightly stouter than P 4 and not tapering so rapidly; 



556-622 67 6 



