PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 623 



aro usually cxpaiulcd; this is a very large species with the length from the proxunal 

 edge of the IBr, to the second syzygy at 9 + 10 up to 17 mm. (In the other species it 

 does not appear to exceed 12 mm.) 



Description (fi-om John, 1938). — The centrodorsal of the most massive specimen is 

 a high rounded cone. LII cirri in three or four rows round the ventral edge are present, 

 while the rest of the surface except for the small smooth dorsal pole is modified with a 

 honeycomb-like growth of stereom. In the other specimens the cirri are XL-LX, 

 25-75. The peripheral cu-ri may be twice as long as the short apical ones. The latter 

 in smaller specimens are of 25 to 35 segments and 10 mm. long and the peripheral cirri 

 are of 38 to 50 segments measuring about 20 mm. or more. In the larger specimens 

 the apical cirri maj' have up to 50 segments and be 16 mm. long, while the peripheral 

 ones are up to 40 mm. 



A large peripheral cirrus has the first four segments much broader than long, the 

 sixth to about the twelfth are very slightly longer than broad. The next four or five 

 are as long as broad, the segments decreasing in length distally, so that the shortest 

 arc twice as broad as long. In the region of the twelfth to fifteenth segments a small 

 swelling appears at the distal end of the dorsal edge. By about the twenty-fifth segment 

 it has developed into a long low keel with a straight edge occupying the distal three- 

 quarters of the dorsal edge. On the shorter distal segments the keel has also become 

 shorter w4th a curved edge. It is reduced on the few segments before the penultimate. 

 The opposing spine is usually strong and erect, the terminal claw moderately strong. 

 There is a sharp difference in color between the first sbc to ten segments, which are 

 yellow, and the rest, which are white. In two specimens the foiu- or five most distal 

 segments are a deep brown. [Note by A.M.C] After 20 years in alcohol the color 

 has been lost. 



The radials are short even in young specimens. They are wider distally than 

 proxunally and have concave distal margins. The IBrj arc three to four times as broad 

 as long. They are not incised by the IBr2 since its posterior projection overlies them. 

 The axillary is considerably broader than long in younger specuncns but nearly as long 

 as broad in the older ones, where the posterior projections are well developed. The 

 lateral edges of the IBrj series are straight and sharp. 



The proximal syzygies are at brachials 3+4, 9+10, and 15+16 (or 14+15) but 

 there are numerous ii'regularities. After the third syzygy the interval is three or four, 

 rarely two or up to seven, muscular articulations. 



The outer edges of the lower brachials are sharp and their sides flat. Their 

 surfaces are smooth but not flat, the inner distal corner of the fourth brachial is raised 

 together wnth the inner proxunal corner of the fifth brachial, into a prominence. Simi- 

 larly the outer distal corner of the fifth brachial with the contiguous corner of the sLxth 

 one are raised, and so on. From the second to the fourth syzygies the brachials become 

 more wedge-shaped. The distal edges of the outermost may be shghtly everted and 

 produced into fine spines. The shape of the brachials then becomes that of a rounded 

 triangle, producing a very zigzag appearance. In the distal brachials the shape again 

 becomes more quadrangular; the distal edges remain everted and spiny. 



The pinnules gradually increase in length towards the tip of the arm. Pj is short 

 and stout, 4 to 5 mm. long and of 9 to 12 smooth rounded segments, which are longer 

 than broad. Pj is similar but may have up to 14 segments and be nearly 8 mm. long. 

 P3 is similar but maj' be longer, likewise P4 if that is not a genital pinnule. Those oral 



