332 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



pinnules and the prominent dorsal processes on the cirri are very similar (see fig. 18, 

 p. 422). Most of the differences between them can be attributed to size. 



Description. The centrodorsal is moderate in size, flattened hemispherical, with 

 numerous (from 60 to 80) cirrus sockets which are closely crowded and irregularly 

 arranged, though on the apical half showing a tendency to become aligned in columns. 

 Beneath each radial there are between 4 and 5 sockets, irregularly alternating higher 

 and lower, one or more being smaller than the others. 



The cirri are XL-L, 27-29, the longest 20-25 mm. in length. The first segment is 

 very short, the second is from half again to twice as broad as long, the third is half again 

 as long as its median width, and the fifth to seventh are about three times as long as 

 their median width ; those following very slowly decrease in length so that the outermost 

 14 or 15 are about as long as the distal width, except that the penultimate, which is 

 narrower than those preceding, is from half again to twice as long as broad and the 

 antepenultimate may be somewhat elongated. The third and following segments are 

 constricted centrally with the dorsal and ventral (and also lateral) profiles markedly 

 and evenly concave and the flaring distal ends overlapping the bases of the succeeding 

 segments all around, though somewhat more strongly dorsally than elsewhere. As the 

 segments decrease in length distally, the dorsal and dorsolateral portions of their distal 

 borders become more strongly produced and at the same time finely spinous, with a 

 prominent tooth in the middorsal line. On the short outermost segments the dorsal 

 surface becomes sharply carinate. As a result of the production of the dorsal surface of 

 the segments the dorsal profile of the outer half of the cirri is very strongly and con- 

 spicuously serrate (see fig. ISc, p. 422). The opposing spine is very small, low, conical, 

 and subterminal in position, rarely somewhat elongated. The terminal claw is as long 

 as, or longer than, the penultimate segment, and is very slender and only moderately 

 curved. 



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

 midradial line but curve strongly upward in the interradial angles where they are con- 

 siderably produced outwardly, the general surface of the interradial triangle formed by 

 the anterolateral portions of two adjacent radials being deeply sunken. The edges of 

 the radials are very finely spinous. 



The IBr! are exceedingly short and bandlike, between 6 and 8 times as broad as 

 the median length, broadly chevron-shaped, with the lateral borders convergent distally. 

 The lateral portions of the distal edge are more or less strongly armed with fine spines. 

 The IBr 2 (axillaries) are rhombic, somewhat broader than long, with all the sides rather 

 strongly and almost equally concave. Their lateral angles project for some distance 

 beyond the obtuse anterolateral angles of the IBr^ The anterior (distal) edges are 

 finely spinous. 



The 10 arms are about 85 mm. long. The first brachials are 5 or 6 times as long 

 exteriorly as interiorly. From the inner side their distal border runs parallel to the 

 proximal border to beneath the posterior projection of the second brachial, then turns 

 distally and runs at an angle of about 45 with the proximal border to the outer distal 

 angle. The distal edge is roughened with numerous very small spines, the roughening 

 being broadest in the middle. The second brachials are very much larger than the 

 first and are irregularly quadrate. Their outer border is about as long as the outer 

 border of the first. A small area, roughly a right angled triangle with the hypotenuse 

 coinciding with the distal border and the opposite angle proximal and median, is 



