140 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



about as long as the penultimate segment or rather shorter, stout, and moderately 

 curved. In the shorter more distally situated cirri, which have usually less than 55 

 segments, the transition segment may be the eighth or even the seventh instead of the 

 ninth as is most commonly the case in the longer cirri. 



The disk is scantily plated, even along the ambulacral grooves, but the brachial 

 and pinnule ambulacra are well plated. The integument along the ambulacral grooves 

 and the entire integument of the ventral surface of the arms is raised into very 

 numerous small papillae which give it a very characteristic appearance. 



The ends of the basal rays are visible as tufts of branching spines hi the interradial 

 angles of the calyx. 



There is a deep but narrow, almost triangular, cleft between the centrodorsal and 

 the radials which is bounded on either side by the proximal cirrus sockets of each 

 column. 



The radials scarcely extend beyond the rim of the centrodorsal; their distal edges 

 are bordered with a row of long papillae or branching spines. The IBri are short, 

 three or four times as broad as long, with the proximal border convex so that they are 

 longer hi the median line than laterally. The proximal and distal edges are somewhat 

 everted and are fringed with branching spines. The IBr 2 (axillaries) are low triangular, 

 about twice as broad as long, with a high sharp median keel in the proximal two-thirds; 

 the borders are everted and fringed with spines, the median keel bears a row of spines 

 along its crest, and there are a few spines scattered over the dorsal surface. IIBr 

 series are present on 3 of the postradial series; 5 of these are 4(3+4) and the sixth is 2. 

 The IIBr series resemble the IBr series. Where the IIBr series are 2 the axillary has a 

 tall sharp median keel like that on the IBr axillary, but the IIB^ is quite without a 

 trace of one. Where the IIBr series are 4(3+4) both the second and fourth elements 

 have similar keels, but the first and third are without them. One of the IIBr series 

 bears a IIIBr series of 2, developed interiorly. The division series and lower brachials 

 are well rounded dorsally and, though usually just in apposition laterally, are not 

 laterally flattened. 



The 17 arms of the type specimen are 180 mm. long and stout. The first brachials 

 are wedge-shaped, rather longer exteriorly than interiorly, with the edges everted and 

 spinous and the dorsal surface evenly rounded. The second brachials are wedge-shaped, 

 also rather longer exteriorly than ulteriorly, with the edges everted and spinous, and 

 with a high narrow sharp median keel like that on the axillaries preceding. The follow- 

 ing 8 brachials are oblong, rather more than twice as broad a long, with the edges 

 everted and spinous and the dorsal surface thickly covered with small sharp papillae. 

 The succeeding brachials are triangular, about as long as broad, with both the proximal 

 and distal edges, but especially the distal, strongly everted and finely spinous, and the 

 dorsal surface roughened. Distally the brachials become wedge-shaped again, then 

 elongate. On the earlier triangular brachials the eversion of the proximal edges 

 gradually becomes obsolete, while that of the distal edges becomes directed forward, 

 forming a strongly overlapping distal border, and develops longer and more numerous 

 spines. On the succeeding wedge-shaped brachials the distal edges are strongly over- 

 lapping and are fringed with rather long spines, while the dorsal surface is covered with 

 longitudinal rows of distally directed spines. 



