672 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Description. — The centrodorsal is hemispherical or rounded conical, nearly covered 

 with cuTus sockets; tlie dorsal pole is commonly studded with papdlae. 



The curi are XI^LX, 23-35 (usually 23-28), 15 or 16 mm. long. The first segment 

 is short, the second is about as long as broad, and the third to eighth are about twnce 

 as long as the proximal width, rather strongly constricted centrally with flaring and 

 overlapping distal ends, the overlap being especially prominent in the median dorsal 

 portion, though the segments cannot bo called spinous; the following segments increase 

 in width from tiie pro.vimal to the distal end, which is slightly overlapping, and grad- 

 ually decrease in length, from the twelfth onward being about as long as broad and 

 more or less strongly carinate in the median dorsal line. The opposing spine is ter- 

 minal, rather less than the width of the penultimate segment in height, and arises 

 from the entire dorsal surface of the latter. The terminal claw is usually rather longer 

 than the penultimate segment, moderatelj' stout and comparatively slightly curved. 

 There are usually a few small cirri situated near the dorsal pole of the centrodorsal which 

 may be less than half as long as the peripheral cirri and are composed of 10 to 12 very 

 slender and much elongated segments with greatly expanded articulations. 



The distal edges of the radials are even with the rim of the centrodorsal and are 

 only very gently concave, not extending up into the angles of the calyx interradially. 

 The IBri are very short, six or eight times as broad as long, bandlike, with a rounded 

 notch in the middle of the distal border. The IBr2 (axillaries) are rhombic, about 

 half again as broad as long, with a rounded posterior projection incising the IBri; 

 the anterior sides are moderately concave, but the anterior angle is not especially prom- 

 inent. The ossicles of the IBr series and the first two brachials are closely crowded 

 against their neighbors and laterally flattened. 



The 10 arms are from 35 to 60 mm. (usually between 50 and 55 mm.) in length. 

 The first brachial is very short, much longer exteriorly than interiorly, and ahnost 

 bisected l)y a posterior projection from the second brachial, which is iiTegularly quad- 

 rate and considerably larger. The first syzygial pair (third and fourth brachials) is 

 about half again as broad as long, slightly longer on the inner than on the outer side. 

 The following brachials to the eleventh are wedge-shaped, much broader than long, 

 with the pro.xunal and distal borders strongly concave; those succeeding become more 

 obliquely wedge-shaped and after the sLxteenth or seventeenth triangular, as long as, 

 or rather longer than, wide, after the proximal third of the arm becoming wedge-shaped 

 again and more elongate, slightly constricted centrally, and distally still more elongate 

 with the ends less and less oblique, and gradually more constricted centrally. The 

 lower brachials have the distal ends strongly and abruptly everted and spinous, standing 

 out perpendicularly and giving the arms a characteristic scalloped dorsal profile; this 

 condition dies away after about the sbcteenth bracliial, the distal edges of the ossicles 

 becoming almost smooth, though under strong magnification they are seen to bear a 

 fringe of short fine spines. 



Syzygies occur between brachials 3-f4, 9-^10, and 14+15, and distally at intervals 

 of 2 (more rarely 3) muscular articulations. 



Pi is 6 mm. long, very slender, with 20 to 25 segments, of which the first 3 or 4 

 are about as long as broad and those following become progressive!}' elongated and 

 exceedingly long and slender distally; after the fourth or fifth the distal ends of the 

 segments become greatly expanded and widely flaring, overlapping the bases of those 

 succeeding. This expansion of the distal ends of the segments, which arises rather 



