A MONOGRAPH OF THE EXISTING CRINOIDS 381 



somewhat, and have very finely spinous distal ends. The longer sides of all the 

 brachials are convex. 



Syzygies occur between brachials 3+4, again about 13 + 14 or 15 + 16, and 

 distally at intervals of 4 or 5 muscular articulations. 



P, is small, slender, flexible, and delicate, 4 mm. long with 15 segments of which 

 the first is much enlarged, as broad as the length of the second brachial and about half 

 as long, the second is smaller, about half again as broad as long, and the remainder 

 are very small, slightly longer than broad. P 2 is 6 mm. or 7 mm. long, moderately 

 stout, stiff, and spinelike, with 15-18 segments, the first large, about twice as broad 

 as long, and oblong, the second smaller, about as long as broad, and the remainder 

 about half again as long as broad, becoming very slightly longer toward the tip where 

 their distal ends are somewhat prominent. P 3 is from 7 mm. to 12 mm. long, most 

 commonly not greatly longer than P 2 , rarely elongated, similar to P 2 but slightly 

 stouter with the articulations slightly swollen. P 4 and P 5 are similar but of decreas- 

 ing length, P 6 being 6 mm. long. The following pinnules are of about the same 

 length, but they have the third, fourth, and fifth segments somewhat expanded and 

 the remainder elongate with projecting distal ends. The expanded portion of the 

 pinnule gradually comes to occupy more and more of its length, the slender tip becom- 

 ing gradually shorter and shorter, while at the same time the pinnule gradually in- 

 creases in length. The distal pinnules are 9 mm. long with 18 segments of which the 

 first is oblong, about twice as broad as long, the second is trapezoidal, somewhat 

 longer than the first, and the following are about twice as long as broad except for 

 the terminal 5 or 6 which are very slender and elongate with overlapping and spinous 

 distal ends. The first three pinnules are rounded prismatic. The distal pinnules 

 are very sharply prismatic and are rather stout and closely set, giving the arm much 

 the same appearance characteristic of the species of Thalassometridae or Charito- 

 metridae in contrast to the conditions seen in Calometra or in Neometra. 



Notes. A specimen from Dr. Sixten Bock's station 36 as described by GislSn 

 has the centrodorsal 2.2 mm. in diameter with the bare dorsal pole 1.5 mm. in diam- 

 eter. The cirrus sockets are arranged in 2 rows and 10 columns. The cirri are 

 XIX, the peripheral with 25-27, the dorsal with 21-24 segments. The fourth seg- 

 ment is a little longer than broad, the fifth and sixth are the longest, one quarter again 

 as long as broad, and the distal are twice as broad as long. From the seventh segment 

 onward dorsal processes are developed which at first take the form of a high thin keel, 

 later shortening into a spine. The opposing spine is similar to the spines on the 

 segments immediately preceding, and reaches one-third the width of the penultimate 

 segment in height. The terminal claw is shorter than the penultimate segment. 

 The radials are produced into interradial projections which separate the IBr^ these 

 last have a median slightly bifid crest and small lateral processes which meet above 

 the processes from the radials; they are three times as broad as long. The IBr 2 

 (axillaries) are twice as broad as long and in the proximal half show a median crest 

 which continues the one on the IBr,. The IIBr series are 2. The 18 arms are 50 mm. 

 long. The brachials do not overlap, and distally become somewhat longer than 

 broad. The arrangement of the syzygies on the 3 arms on one ray is as follows: 

 In the outer arm arising from the IIBr series, between brachials 3+4, 13 + 14, 19 + 20, 

 25+26; in the inner arm arising from the IIBr series, between brachials 3+4, 12 + 13, 



