PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 689 



p. 671 (comparison with syntypes); text-fig. 3. — Tortonese, Bull. Inst. Oc6anogr. Monaco, 

 No. 956, 1949, p. 4 (depth range). — Gisl6n, Rep. Swedish Deep Sea Exped., vol. 2, Zool., No. 

 4, 1951, p. 56 (depth range). 



Diagnostic features. — The cirri are XXX-XTj, 19 to 29, with tlie longer segments 

 about twice as long as their median widths; P, has about 20 segments, of which the 

 distal ones arc not expanded or spinous at the ends. 



Description [modified by A.M.C.]. — The centrodorsal is broadly rounded conical, 

 the blunted apex distinctlj- rugous; the well-defined cirrus sockets tend to form irregular 

 vertical columns. All the cirri are now lost but for one which is nearly apical on the 

 syntype with the arms broken off short. There are XXX-XL sockets. The single 

 cirrus has 20 segments, of which the more proxmial are strongly constricted centrally 

 with the distal ends flared. The longest segments are about twice as long as their 

 median widths or about a third again as long as their maximum widths. Beyond the 

 tenth the segments are as broad as long or broader and have a slight dorsal keel. The 

 peripheral cirri would have been longer with possibh' half again as manj^ segments. 



The distal edges of the radials are just visible beyond the rim of the centrodorsal. 

 The IBr, are nearlj- oblong, three or four times as broad as long, rather strongly convex 

 dorsally and considerably incised by the broadly rounded proximal angle of the IBr2 

 (axillaries) . The latter are rhombic, broader than long, with a slightly prolonged 

 distal angle and strongly concave distal sides. The IBr2 and the first two brachials 

 have traces of spinous lateral processes, which in one syntype form a kind of frill. 



The 10 arms were probably about 40 mm. long. The first syzygy is respectively 

 0.85 and 1.0 mm. wide in the two 3301 types and in the larger the length from the proximal 

 edge of the IBri to the second sj^zygy at 9-flO is 7.0 mm. The second syzygj- may be 

 beyond brachials 9 and 10 and the third one is even more irregular. Distall3' the m- 

 terval is from three to five muscular articulations. 



The first two pairs of pinnules are ver\' long, slender and delicate, and were probably 

 about equal in length. All are broken, but one P^ is almost complete; it has 20 seg- 

 ments, of which the outer ones are very attenuate, more than six times as long as broad. 

 The joints are only slightly expanded. The first two or three segments are compressed 

 lateralh' and enlarged dorsoventrally so that in side view the tapering is very noticeable. 

 The total length is about 7 mm. No Pi is complete beyond the tenth segment or P2 

 bej'ond the fifteenth but each probably had a total of at least 20 segments. P3 is the 

 first genital pinnule. All are broken. The outer segments of the following genital 

 pinnules are so attenuate as to be almost transparent. 



N^otes. — Some additional specimens were taken by the Scotia off the South Orkney 

 Islands in the Weddell Sea. These were described and figiu-ed by Dr. DilwjTi John. 

 They are similar in size to the syntypes. 



The centrodorsal is hemispherical, about twice as broad as high. Its ventral edge 

 is nearly straight. The cirrus sockets are arranged in alternate rows around the sides 

 leaving the dorsal pole smooth and rounded. 



The cirri are about XL, 20-29, the peripheral considerablj' longer than the apical 

 ones. A peripheral cirrus has the first two segments short, the third longer than broad 

 and the fifth twice as long as the median diameter. Beyond the fifth the segments 

 decrease in length to become only a little longer than wide. The third to the nintli 

 segments are constricted in the middle and expanded at the distal ends, though not as 

 much as in the apical cirrus of the syntype, or indeed as in the apical cirri of the same 



