450 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



are commonly variable in size, are arranged in from two to three irregular rows on the 

 proximal two-thirds of the centrodorsal, bej^ond which is the bare conical tip, though 

 this may be absent. The cirrus sockets may be closely crowded, or more or less isolated. 



The cirri are XXX-XXXV, 50-71 (usually 60-65), from 65 to 75 nun. in length, 

 very long, slender and deUcate, and almost straight. The first three segments are more 

 than twice as broad as long, the fourth is half again as broad as long to neariy as long as 

 broad, and the sixth and following are about twice as long as broad, or slightly longer; in 

 the outer half of the cirri the segments decrease very gradually in length so that the 

 last half dozen are about as long as broad. After about the seventh or eighth the 

 median portion of the distal dorsal edge slowly becomes prominent so that in the 

 outer half of the cii-ri each segment bears a small but prominent blunt spine directed 

 obhquely forward and very slightly overlapping the base of the succeedmg segments. 

 These spines are confined to the distal portion of the segments and are rounded dorsally 

 until about the last sLx, when they come to arise gradually from the entire dorsal 

 surface of the segments and become more or less sharply carinate, at least distally. 

 In the terminal quarter the curi taper very shghtly. The penultimate segment is 

 rather small, slightly longer than broad, and bears a blunt opposing spine directed 

 obliquely forward. The terminal claw is somewhat longer than the penultimate 

 segment, slender, and only very moderately curved. 



There are no basal rays. 



The distal portion of the radials projects as a narrow band of approximately 

 uniform width beyond the rim of the centrodorsal. The IBrj are very short, from 4 to 6 

 times as broad as the lateral length, more or less incised in the middle by a rounded pos- 

 terior projection from the axillaries; their sides are parallel, and parallel with those of 

 their neighbors, from which they are separated by a very narrow interval. The IBrj (ax- 

 illaries) are rhombic, broader than long, with a more or less, though never very strongly, 

 developed rounded posterior process, a truncated and shghtly notched distal angle, 

 and, in the more mature individuals, strongly concave sides. In the proximal half 

 or third the IBro bear a more or less elevated, and often high, carination which may 

 have a plain or serrate crest. Beneath the lateral angles there is a more or less developed 

 rounded lateral extension covered with very fine spines. 



The 10 arms are 115 to 165 mm. (commonly about 150 mm.) in length. The 

 first brachial is about 3 times as long exteriorly as interiorly, with the proximal and 

 distal edges parallel in the inner half and widely diverging in the outer; the inner 

 edges of the 2 first brachials on each arm pair are not in contact basally, and are 

 shghtly divergent. The second brachials are much larger, irregularlj" quadrate, with 

 a high keel or a series of laterally flattened tubercles in the proximal two-thirds 

 to three-fourths. The first syzygial pair (composed of brachials 3 + 4) is slightly 

 longer interiorly than exteriorly, about as broad as the interior length; the epizj'gal 

 bears in its proximal portion an abrupt and usuallj' high median laterally flattened 

 tubercle, or sometimes two arranged in tandem. The next 6 or 7 brachials are wedge- 

 shaped, about twice as broad as the median length, each with a high median tu- 

 bercle or longitudinal keel, the crest of which may be notched in the middle. The 

 following brachials are much more obliquelj' wedge-shaped, about as long as broad, 

 becoming longer than broad terminallj'; they arc narrow and high, and strongly cari- 

 nate in the median line, the narrowl}' rounded keel being high distally and rapidly 

 falling away to the proximal border so that the profile of the arms is very strongly 



