294 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



smooth, with the earlier segments keeled. The cirri are 23-25 mm. long with 31-35 

 segments of which the longest are about as long as broad or slightly longer than broad, 

 and the outer are from half again to twice as broad as long and bear dorsal tubercles. 

 The 16-25 arms are 125 mm. long. P t and P 2 are of the same length and similar with 

 26 segments and are much longer and slightly stouter than P D . P 3 is scarcely longer 

 than P D . 



Description. The centrodorsal is discoidal, with the bare polar area flat, slightly 

 convex or slightly concave, about 5 mm. in diameter. The cirrus sockets are arranged 

 in a single more or less irregular marginal row. 



The cirri are XVIII-XXIII, 31-35, from 23 to 25 mm. long. The first segment is 

 very short, the next three are nearly two and one-half times as broad as long, and 

 those following gradually increase in length to the sixth or seventh, which is about 

 as long as broad. The next five to seven segments are usually slightly longer than 

 broad, sometimes squarish, the following gradually decreasing in length so that the 

 terminal fifteen or rather more are from half again to twice as broad as long. At 

 about the fifteenth segment dorsal tubercles are developed, at first involving only 

 the distal portion of the dorsal surface, later arising in a slightly convex line from 

 near the proximal end, the apex being sub terminal; these tubercles are narrow, laterally 

 occupying only a small portion of the median part of each segment, and are slightly 

 rounded dorsally. On the last three segments the tubercles become somewhat 

 sharper, more erect, and move to a median position. The opposing spine is small, 

 though larger than the tubercle on the preceding segment, blunt, arising from the 

 entire dorsal surface of the segment, the apex median or sub-median in position, in 

 height equal to about one-third the lateral width of the penultimate segment. The 

 terminal claw is somewhat longer than the penultimate segment, rather stout and 

 strongly curved. 



There are no basal rays. 



The radials are concealed by the centrodorsal. The IBri are very short and band- 

 like. The IBr 2 (axillaries) are short, almost triangular, two and one-half times as 

 broad as long. The IIBr are 4 (3+4), hi apposition laterally, though not laterally 

 flattened; the 116^ are entirely united interiorly. The IIIBr series are 2, rarely 4 

 (3+4). The IVBr series are 2, but are rarely present. 



The 16-25 arms are 110 mm. long. The first two brachials are wedge-shaped, 

 three times as broad as long exteriorly, the first interiorly united. The next four or 

 five brachials are oblong, about four times as broad as long, and those following gradu- 

 ally becoming wedge-shaped, almost triangular, about three times as broad as long, 

 and less oblique and somewhat longer in the outer portion of the arms. The distal 

 portion of the arms is perfectly smooth dorsally. 



Syzygies occur between brachials 3+4, again between brachials 13+14 to 

 20+21 (usually in the vicinity of the fifteenth) and distally at intervals of 7-11 (most 

 commonly 8 or 9) muscular articulations. 



P D is 7.5 mm. long, moderately stout basally but tapering rather rapidly in the 

 proximal half and becoming slender distally, with 25 segments, which at first are 

 twice as broad as long, becoming as long as broad after the tenth; the first four seg- 

 ments are strongly carinate, this carination decreasing distally and disappearing after 

 the middle of the pinnule. P! is 13 mm. long, slightly stouter than P D basally, taper- 



