78 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Diagnostic features. The cirri are very long and slender, from a third to half the 

 length of the arms, composed of 25 to 33 (usually 25 or 26) much elongated segments 

 of which the longest are about five times as long as the proximal width and the last 

 three or four are from two and a half to three times as long as broad; there is no 

 opposing spine and the terminal claw is very slightly curved. The arms are up to 

 80 mm. and the cirri between 30 and 40 mm. in length. 



Description. The centrodorsal is hemispherical, rather low; the cirrus sockets are 

 arranged in four or five closely crowded alternating rows. 



The cirri are XL^LX, 25-33 (usually 26), from 30 to 40 mm. long. The first 

 segment is very short, the second is about as long as broad, the third is about half 

 again as long as broad, the fourth is nearly four times as long as its proximal diameter, 

 and the fifth and following are about five times as long as their proximal diameter; the 

 terminal ten to twelve segments decrease very slightly in length, so that the last three 

 or four are only about two and a half times as long as broad. The penultimate segment 

 is slightly over twice as long as its proximal diameter, decreasing slightly in width 

 distally. There is no opposing spine. The terminal claw is about three-quarters the 

 length of the penultimate segment, slender, evenly tapering, and very slightly curved. 

 The cirri are rather strongly compressed laterally throughout, and the distal half 

 of each segment slightly and very gradually increases in diameter so that the distal edge 

 is prominent. 



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

 IB^ are extremely short, almost divided in the median line by a posterior projection 

 from the axillaries, with a more or less prominent rounded tubercle hi each anterolateral 

 angle. The IBr 2 are rhombic, about half again as broad as long, with the sides strongly 

 concave and the anterior angle sharp and somewhat produced. The elements of 

 the IBr series and the first two brachials are in close lateral apposition with their neigh- 

 bors. The synarthrial tubercles on the articulations between the elements of the IBr 

 series and the first two brachials are very prominent. 



The 10 arms are 80 mm. hi length. The first brachials are about twice as long 

 exteriorly as interiorly, and are deeply incised in the median line; the bases of adjacent 

 first brachials just meet over the anterior angles of the axillaries. The second brachials 

 are much larger, irregularly quadrate, with a strong posterior process incising the first 

 brachials. The first syzygial pairs (composed of the third and fourth brachials) are 

 rather more than twice as broad as long in the median line, and rather longer inwardly 

 than outwardly. The next four brachials and the second syzygial pair (composed of 

 the ninth and tenth brachials) are slightly wedge-shaped, and about twice as broad as 

 long. The succeeding brachials become triangular, at first not so long as broad, soon 

 becoming as long as broad, and distally wedge-shaped again and, in the terminal portion 

 of the arms, elongate. The brachials are smooth and do not overlap. 



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

 of hi one specimen 3 and in another 4 muscular articulations. 



P! is 6 mm. long, somewhat stiff, slightly compressed, tapering evenly from the 

 base to the tip, composed of 12 segments of which the first is not so long as broad, the 

 third is slightly longer than broad, the fourth is about half again as long as broad, and 

 the remainder are about twice as long as broad. P 2 is half as long again as Pj, 9 mm. 

 in length, stouter and stiffer than P!, with about 16 segments, of which the first is about 



