A MONOGRAPH OF THE EXISTING CRINOIDS 249 



P b is 4.2 mm. long with 9 segments. P 3 is 3.2 mm. long with 7 or 8 segments. P 4 is 

 2.5 mm. long with 8 segments. The distal pinnules are 5 mm. long with 16 segments. 



In a seventh specimen from station 43 the cirri are XXIII, 14-16, from 2.5 to 

 3.5 mm. long. P 2 is 3.3 mm. long with 8 segments. P b is 3.3 mm. long with 8 seg- 

 ments. P 3 is 3 mm. long with 8 segments. The disk is 3.5 mm. in the longest and 

 2 mm. in the shortest diameter. 



In a specimen from station 53 the cirri are XXV, 15, from 4 to 5 mm. long. 

 The opposing spine equals in height two-thirds the width of the penultimate segment. 

 The 10 arms are 27 mm. long. P 2 is 3.5 mm. long with 8 segments. P b is 3.5 mm. 

 long with 8 segments. P 3 is 3 mm. long with 8 segments. P 4 is 2.7 mm. long with 

 8 segments. The distal pinnules are 4 mm. long with 15 segments. The disk is 3 

 mm. in diameter and is not distinctly incised. The anal cone is 2 mm. high. 



In another specimen from station 53 the cirri are XIV, 12-15, from 3 to 4.5 mm. 

 long. The 10 arms are from 15 to 20 mm. long. P 2 is 3 mm. long with 9 segments. 

 PS is 2.5 mm. long with 9 segments. The distal pinnules are 4 mm. long with about 

 15 segments. The disk is 2.5 mm. in diameter. 



A specimen from Willebrord Snellius station 60* does not seem to differ in any 

 essential particular from those from the Bonin Islands described by Gisl6n. It was 

 compared directly with one of these specimens, which the Museum owes to the kind- 

 ness of Dr. Gisl6n, and the only differences found, the slightly fewer cirrus segments, 

 and the greater length and slenderness of the fewer segments of the lower pinnules, 

 are undoubtedly due to its smaller size. It may be described as follows: 



The centrodorsal is discoidal, with the flat dorsal pole completely covered with 

 numerous closely crowded rounded or more or less conical tubercles. The cirrus 

 sockets are arranged in two closely crowded alternating rows. The cirri are XXII, 

 13-16 (usually 15), 4.5 mm. long. The first segment is very short, the second is 

 about one-third again as broad as long, the fourth and fifth are slightly longer than 

 broad, and those following slowly decrease in length so that the last four or five are 

 slightly broader than long. The second and following segments have the distal dorsal 

 edge raised and finely serrate, this almost immediately becoming a transverse ridge 

 with a more or less strongly convex crest, rarely with prominent lateral angles; this 

 transverse ridge gradually narrows distally so that the last two segments before the 

 penultimate have a sharp median carination. The opposing spine is equal in length 

 to about two-thirds the width of the penultimate segment, and is long, sharply pointed, 

 slender, with the apex terminal or subterminal. The terminal claw is slightly longer 

 than the penultimate segment and is moderately and evenly curved, slightly more 

 so proximally than distally. 



The radials are short, 5-6 times as broad as the median length, with the distal 

 border approximately straight in the central two-fourths and curving broadly upward 

 and outward in the lateral fourths. Their anterolateral angles are separated by a 

 deep and rather broad U-shaped gap. The IBr! are about 5 tunes as broad as long in 

 the median line and about twice as long laterally as in the median line, the distal 

 border being deeply incised by a posterior projection from the axillary. The IBr 2 

 (axillary) is shield-shaped, slightly broader than long, with the two distal edges rather 

 strongly concave, a sharp and somewhat produced distal angle, and the posterior 



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