A MONOGRAPH OF THE EXISTING CRINOIDS 67 



On the basis of 15 specimens from Mjoberg's stations 4, 10, and 13 Dr. Torsten 

 Gislen redescribed adeonae as follows: 



The centrodorsal is discoidal to hemispherical, the bare dorsal pole a little convex 

 with small pits and knots, 2.5 mm. in diameter. The cirri are arranged in two rows. 



The cirri are XIX-XXXV, 19-32 (22-32 in the upper and 19-29 in the lower 

 row), about 12 mm. long. The first segment is short. The four following are broader 

 than long, and those succeeding are about as long as broad, or a little longer than 

 broad. The penultimate segment is shorter again. The outer segments are provided 

 with two groups of processes, a proximal transverse ridge and a distal row of spines. 

 The proximal transverse ridge is straight and even, and is situated at the proximal 

 border of the segment. The distal transverse ridge is situated on the distal part of 

 the segment and is somewhat curved with irregular protuberances at the margin; 

 on the distal segments these are prolonged into two blunt lateral spines. The proximal 

 transverse ridge usually appears somewhat before the distal one. The distal borders 

 of the segments on their ventral side are bent a little outward, which gives the cirri 

 a somewhat uneven margin. The opposing spine occupies only a portion of the 

 dorsal surface of the penultimate segment, and reaches a height equal to one-third 

 the width of the segment. The proximal transverse ridge often still remains on the 

 penultimate segment. The terminal claw is stout, strongly curved, and about as 

 long as the penultimate segment. Fully developed cirri usually show the proximal 

 transverse ridge on about the fifth and the distal on the eighth-thirteenth segments. 

 The dorsal processes are developed first on the proximal segments, and last of all on 

 the distal ones. 



The radials are visible as narrow bands, or are concealed by the centrodorsal 

 except hi the interradial angles of the calyx. The median portion has one or more 

 distinct tubercles, and similar tubercles are often found on the proximal portion of 

 the IBri. The IBr: are three times as broad as long, and are united in their basal 

 halves. With the IBr 2 (axillaries) they form a synarthrial tubercle which is separated 

 from the remaining portion of the ossicles by shallow grooves. The distal angle of 

 the IBr 2 is less than 90. 



The 10 arms are 50-70 mm. long. The first brachials are interiorly united 

 basally, and form a synarthrial tubercle with the second. The ossicles from the IBri 

 to the second brachials have ventrolateral flanges that encircle a narrow U-shaped 

 gap between the arms. The fourth-ninth brachials have prominent and swollen 

 distal borders. The prominence on the fourth brachial is most strongly developed 

 interiorly, so that there is a prominence directed backward alternately on the exterior 

 and interior of the arm. In addition, on these segments proximally developed 

 tubercles often form an indistinct median ridge. After the second syzygy the brachials 

 grow smoother and are wedge-shaped. 



The first syzygy is between brachials 3+4, and the second is from the eighth 

 to the eleventh segment. The distal intersyzygial interval is 4 muscular articulations, 

 syzygies occurring, for instance, between brachials 9+10, 14+15, 19 + 20, etc. 



PI is from 10 to 15 mm. long with 13-20 segments. The first segment is about 

 as long as broad, the second is half again as long as broad, and the third, fourth, and 

 fifth are more than twice as long as broad; the segments following are shorter again, 

 always, however, a little longer than broad. The pinnule is smooth, strongly com- 



