A MONOGRAPH OF THE EXISTING CRINOIDS 273 



Another specimen from Bock's station 55 has the cirri XVI, 8, 2 mm. long. 

 The 10 arms are 18 mm. long. Pi and P2 bear combs. The gonads are somewhat 

 swollen. 



Another specimen from Bock's station 55 has 10 arms. On some of the arms 

 P2 is lacking; if present it bears a comb like Pi. 



Another individual from Bock's station 55 has the cirri XV, 9, 3 mm. long. The 

 radials are partially visible. The IBri are six times as broad as long. The IBrj 

 (axillaries) are three times as broad as long. Pi and P2 have combs. 



In another specimen from Bock's station 55 the cirri are XVI, 9, from 1.5 mm. 

 to 2.5 mm. long. The third segment is the longest, three and one-half times as long 

 as broad. The antepenultimate segment is one-third again as long as broad. The 

 radials are visible as narrow bands. The IBri are six times as broad as long. The 

 IBr2 (axillaries) are twice as broad as long. There are 10 arms. Pi bears a comb. 

 Pj is absent. 



In another specimen from Bock's station 55 the cirri are XIX, 10, 3 mm. long. 

 There are 10 arms. Pi and P2 bear combs. 



In the last specimen from Bock's station 55 the cirri are XIX, 9, 2.5 mm. long. 

 The antepenultimate segment is one-third again as long as broad. The IBri are six 

 times as broad as long. The IBr2 (axillaries) are three times as broad as long. The 

 10 arms are about 15 mm. long. Pi has a comb with 9 teeth. P2 is absent from 

 some arms; if present it bears a comb. 



In a specimen from Bock's station 61 the cirri are XIII, 10, 3 mm. long. The 

 radials are concealed. The IBri are four times as broad as long. The 10 arms are 

 15 mm. long. The intersyzygial interval is 3 muscular articulations. Pi has a comb 

 with 8 teeth. P2 is inconspicuous or absent. The distal pinnules are 3 mm. long 

 with 12 segments. 



The second specimen from Bock's station 61 has the cirri XII, 8-9, from 2 mm. 

 to 2.5 mm. in length. The IBri are twice as broad as long. The IBr2 (axillaries) are 

 half again as broad as long. The 10 arms are 12 mm. long. Pi has a comb consist- 

 ing of 8 teeth. P2 to P4 are lacking. 



Doctor Gisl^n remarks that it is interesting to observe the relation between the 

 length and breadth of the most proximal arm ossicles. In the smallest specimens the 

 radials are plainly visible. The IBri arc rather long in the smaller specimens, from 

 two to three times as broad as long, but they become shorter during growth, so that, 

 if not almost completely concealed by the centrodorsal, they are from six to eight 

 times as broad as long. The length of the IBr2 (axillaries) also usually decreases 

 from half again as broad as long to five times as broad as long. This ossicle is never 

 concealed by the centrodorsal. 



Localities. — Dr. Sixten Bock's station 42; Bonin Islands; west of Port Lloyd; 

 128 meters; July 31, 1914 [Gisl<5n, 1922]. 



Dr. Sixten Bock's station 45; Bonin Islands; east of Chichijima; 146 meters; 

 July 31, 1914 [Gisl^n, 1922] (1, U.S.N.M., E. 1115). 



Dr. Sixten Bock's station 45A; Bonin Islands; east of Chichijima; 104 meters; 

 July 31, 1914 [Gisl6n, 1922]. 



Dr. Sixten Bock's station 47; Bonin Islands; east of the channel; 146 meters; 

 August 1, 1914 [Gisldn, 1922]. 



