J74 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Description. — The centrodorsal is hemispherical, rather low, with a comparatively 

 large bare polar area, and bears from 20 to 30 cirrus sockets in two or three irregular 

 nuirginal rows. 



The cu-ri arc XV-XXX (usually about XXV), 12-14, from 7 to S mm. in length. 

 The fii-st segment is short, the second about as long as broad, the third about half again 

 as long as broad, and the fourth about twice as long as its median diameter; the follow- 

 ing segments become very gradually shorter, the antepenultunate being about half again 

 as long as broad, or even rather shorter, and the penultimate about as long as broad. 

 The segments have somewhat expanded distal ends which overlap the proxunal ends of 

 those succeeding; the earlier also have swollen proximal ends. The cirri are very 

 slender proxunally but increase somewhat in dorsoventral diameter distally and become 

 slightly compressed laterally after the fu-st few segments. The opposing spine is always 

 present, though apparently variable in size. The terminal claw is rather large, usually 

 about half again as long as the penultimate segment, stout, and strongly curved. 



The distal borders of the radials arc even with the edge of the centrodorsal. The 

 IBri are oblong, about twice as broad as long, rounded laterally and widely separated, 

 the anterior border concave to receive a slight posterior projection from the IBro (axil- 

 lary) which is broadly pentagonal, not quite half again as broad as long, and may rise 

 into a very slight rounded tubercle on the articulation with the IBrj. 



The 10 arms are usuaU}"^ from 30 to 35 mm. long, rarely longer, though individuals 

 occur with an arm length of as much as 70 mm., whQe sexual maturity may have been 

 reached in animals with an arm length of only 20 mm. The first brachials are short, 

 longer outwardl}' than inwardly, the anterior border incised by a slight backward 

 projection from the larger and irregularly quadrate second brachial. The first sj^zj-gial 

 pair (composed of the third and fourth brachials) is about as long inwardly as broad, 

 slightly shorter outwardlj^, the epizygal being oblong and the hypozygal wedge-shaped 

 or almost triangular with the apex outward. The fifth to eighth brachials are oblong or 

 slightl3' wedge-shaped, about twice as broad as long. The following brachials are 

 wedge-shaped, at fii-st not quite so long as broad, but soon becoming as long as broad 

 and distally longer and gradually less obliquely wedge-shaped, the termmal brachials 

 being practically oblong, half again to twice as long as broad, but cylindrical with no 

 trace of a central constriction. 



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

 of 3 muscular articulations. 



Pi is 4 mm. long, composed of 10 segments, moderately stout and tapering evenly 

 from the base to the dehcate tip. The first segment is very short, about three times as 

 broad as long, the second is about as long as broad, the third is about half again as long 

 as broad, and the following become gradually more and more elongated. The third 

 and following segments have the distal edges prominently everted dorsally and laterally 

 (but not ventrally) so that the dorsal profile of the pinnule is strongly serrate. P2 

 is about half as long as ?,, but similar to it. It is ahnost equally stout at the base, 

 but tapers more rapidly and its 7 or 8 segments are proportionately shorter than 

 the segments of P,, but show the same eversion of the distal edges. P3 is intermediate 

 in length between P, and Pj, composed of 10 segments which resemble those of Pi. 

 but the third to sixth carry a gonad. The following pinnules to the si.xteeuth are 

 similar, but the eversion of the distal ends of the segments gi-adually becomes less 

 and less and dies away entirely after about the tenth. The distal pinnules are about 

 5 mm. long, moderately slender, the first segment rather less than half as long as 



