274 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Dr. Sixten Bock's station 55; Bonin Islands; eastnortheast of Chichijima; 210 

 meters; August 15, 1914 [Gisle"n, 1922]. 



Dr. Sixten Bock's station 61; Bonin Islands; eastsoutheast of the channel; 152 

 meters; August 16, 1914 [Gisle"n, 1922]. 



Geographical range. Only known from the Bonin Islands. 



Bathymetrical range. From 128 to 210 meters; the average of six records is 158 

 meters. 



Remarks. Doctor Gisle"n says that these specimens approach Comissia ignota, 

 from which they differ in having, on the average, more cirri, by showing certain 

 differences in the proportions of the cirrus segments, in their smaller size, etc. 



History. This species is only known from the 29 specimens collected by 

 Dr. Sixten Bock in 1914 and admirably described by Dr. Torsten Gisle"n in 1922. 



COMISSIA SCITULUS (A. H. Clark) 



Co-master (?) scitulus A. H. CLARK, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 534 (description; Alba- 

 tross station 5356). 



Comissia scitulus A. H. CLARK, Ann. and Mag. Nat. Hist., ser. 8, vol. 7, 1911, p. 645 (listed, with 

 habitat); Crinoids of the Indian Ocean, 1912, p. 77 (synonymy; range). 



Diagnostic features. The cirri are XIX, 10-12, from 5 mm. to 6 mm. long; the 

 longest cirrus segment is about four times as long as the width of its proximal end, and 

 the penultimate segment is twice as broad as long. The arms are about 60 mm. 

 long. The IBr t are about four times as broad as long, and the axillaries are twice 

 as broad as long. The elements of the IBr series and the first 2 brachials have everted 

 and spinous distal ends, and the following brachials have strongly produced and 

 overlapping coarsely spinous distal ends. The terminal comb on P! consists of 7-8 

 small and well-separated teeth, with similar but smaller teeth on the opposite sides 

 of the segments. 



Description. -The centrodorsal is thin discoidal, with the dorsal pole flat, 1.5 

 mm. in diameter. 



The cirri are XIX, 10-12, from 5 mm. to 6 mm. long. The first segment is short, 

 the second is somewhat longer than the width of its expanded ends, the third is from 

 two to two and one-half times as long as the width of its expanded ends, and the fourth, 

 which is a transition segment, is the longest, about four times as long as the width of 

 its expanded proximal end. The following segments become very rapidly shorter, 

 and at the same time become laterally compressed and therefore broader in lateral 

 view. The penultimate segment is twice as broad as long. The fourth and following 

 segments have the distal edge thickened on the dorsal side, and small sharp subter- 

 minal dorsal tubercles which become median on the antepenultimate. The opposing 

 spine is prominent, but small, terminal, erect or nearly erect, in height equal to about 

 one-third the lateral width of the penultimate segment. The second and third seg- 

 ments have considerably expanded ends. The fourth segment has the distal end much 

 expanded, this feature gradually dying away distally. The terminal claw is nearly 

 twice as long as the penultimate segment and is rather slender and moderately curved. 



The radials are concealed by the centrodorsal. The IBi^ are very short, oblong, 

 about four times as broad as long, in apposition laterally. The IBr 2 (axillaries) are 

 nearly triangular, twice as broad as long, with a shallow groove on the dorsal side 

 at the anterior angle, as in Comatula pectinata. 



