A MONOGRAPH OF THE EXISTING CRINOIDS 263 



long as the median width, and the third is a transition segment, five or six times as 

 long as the median width; the following segments rapidly decrease in length so that 

 the 4 or 5 before the penultimate are from one-third to one-half again as long as 

 broad and the penultimate is about as long as broad. The elongate earlier segments 

 have rather strongly concave profiles. The third segment has the dorsal portion of 

 the distal edge slightly produced and armed with very fine spines. This production 

 narrows on the succeeding segments so that the last 3 or 4 before the penultimate 

 have a very slight subterminal dorsal tubercle. The opposing spine is very small, 

 though sharp, median or subterminal. The terminal claw is somewhat longer than 

 the penultimate segment, slender, and less strongly curved distally than proximally. 



The ovaries are enormously swollen and contain mature, or nearly mature, eggs. 

 The 3 specimens from station 46 are small. 



The example from Siboga station 95 has the cirri about XX, 11, 7 mm. long. 

 The dorsal pole of the centrodorsal is 2 mm. in diameter. 



The largest individual from Siboga station 105 has the cirri XXII, 10-11, 7 mm. 

 long. The dorsal pole of the centrodorsal is 2.5 mm. in diameter. The ovaries 

 contain mature, or almost mature, eggs. The other 4 specimens are very small. 



The Siboga specimen with the label illegible has the cirri XXIII, 11-13, 9 mm. 

 long. The dorsal pole of the centrodorsal is fiat, 2 mm. in diameter. The arms are 

 45 mm. long. Ripe eggs are present in the ovaries. 



The specimen from Bock's station 37 has the centrodorsal discoidal, 2.5 mm. in 

 diameter, the dorsal pole being 1.5 mm. in diameter. 



The cirri are arranged in one and a partial second marginal row. 



The cirri are XXI, 10-13, from 6.5 mm. to 8 mm. in length. The first segment is 

 broader than long (as shown in GisleVs figure), the second is half again as long as 

 broad, and the third is the longest and most slender, 3 times as long as broad. The 

 fifth and following segments are shorter and somewhat broader in lateral view, half 

 again as long as broad (the figure shows them about as long as broad). From about 

 the fifth segment onward small dorsal tubercles are developed. The antepenultimate 

 segment is about one-fifth again as long as broad. The opposing spine is inconspicuous. 

 The terminal claw is curved, pointed, and somewhat longer than the penultimate 

 segment. 



The radials are concealed. The IB^ are visible as narrow bands about six 

 times as broad as long. The IBr 2 (axillaries) are low pentagonal or triangular, twice 

 as broad as long. 



The 10 arms are from 45 to 50 mm. in length. The first brachials are almost 

 wholly free interiorly. The second brachials are about twice as long exteriorly as 

 interiorly. After the seventh or eighth brachial the articulations become oblique. 

 The width of the brachials in the middle of the arms is about 1 mm. They are about 

 as broad as the greater length. The distal brachials are smooth and not overlapping. 

 There are 15 brachials for each 10 mm. of arm length, or 11 if the syzygial pairs are 

 counted as single units. 



Syzygies occur between brachials 3 + 4, 11 + 12, 14 + 15, 18 + 19, 22 + 23, and 

 distally at intervals of 2 or 3 muscular articulations. 



