64 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



The 10 arms are about 50 mm. long, with about 80 bracbials finely spinous along 

 their distal edges. The distal intersyzygial interval is three or four muscular articu- 

 lations. The width at the first syzygy (3+4) is 1.0 mm, and the length from the 

 proximal edge of the IBr : to the second syzygy (9 + 10) is 5.5 mm. 



PI has up to 15 segments and is 3.5-3.8 mm. long. 



P 2 is larger with 15+ segments and is over 5 mm. long. 



P 3 is larger still with 18 segments and measures 8 mm. It bears an elongate gonad. 



The color when freshly preserved was purplish red with frequent intervals of white 

 on the arms. The type specimen of Iridometra scita was purple with darker blotches. 



Notes. By some curious mischance the relative sizes of the proximal pinnules 

 were wrongly given in the original description of Iridometra scita, which was said to 

 come nearest to Andromctra psyche and to have P 2 much the largest and longest pinnule 

 on the arm. 



In the type specimen of Iridometra scita the cirri are about XXXV, 13-15, 10 mm. 

 long; the longest segments (the third and fourth) are twice as long as the diameter of 

 their expanded ends ; the last two before the penultimate are only slightly longer than 

 broad. 



The 10 arms are 60 mm. long. 



Pj is 3.2 mm. long with 10 or 1 1 segments. P 2 is 6 mm. long with 13 or 14 segments, 

 proportionately stouter than P,. P 3 is from 9 to 10 mm. long with from 17 to 19 seg- 

 ments, and is the longest and stoutest pinnule on the arm. P 4 is 4.5 mm. in length, 

 with 13 segments. P 5 is 4.5 mm. long with 12 segments, slightly stouter than P 4 and 

 bearing a gonad. 



There can be no doubt that Iridometra scita and Carpenter's Antedon parvicirra 

 represent the same species. 



Dr. T. Gisl^n gave in detail the characters of two of the three specimens from the 

 Bonin Islands studied by him; the specimens differ from the preceding only in being 

 smaller. 



The centrodorsal is hemispherical to dome shaped with the dorsal pole papillated; 

 the cirrus sockets are arranged in two or three irregular rows. 



The cirri are about XXV-XXX, 11-14, from 2.5 to 7 mm. long; the third to sixth 

 segments, which are the longest, are from two to two and a half times as long as broad, 

 slightly constricted centrally; the antepenultimate segment is twice as broad as long; 

 the height of the opposing spine, which is directed obliquely forward, is from a half to 

 two-thirds the width of the penultimate segment; the terminal claw is slender, sharp, 

 slightly curved, and as long as the penultimate segment. 



The radials are almost concealed by the centrodorsal. The IBrj have an antero- 

 lateral tubercular extension. The axillaries are rhombic, as long as broad, the lateral 

 angles with slight tubercles. 



The arms are from 20 to 35 mm. long. The first brachials are twice as long exte- 

 riorly as interiorly, and in contact with their neighbors interiorly. The first 10 

 brachials are more or less oblong, the ends of those following becoming oblique. 



Syzygies occur between brachials 3 + 4, 9 + 10, 14 + 15, and distally at intervals of 

 3 muscular articulations. 



The disk is smooth, without granules. 



P : is from 2 to 2.7 mm. long with 8 or 9 segments of which the first is short, the 

 second is as long as broad, the third is half again as long as broad, and the outer are 



