422 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



a 

 b 



f El 



r 3 



FIGURE 18. a, ISolanometra antarctica (P. H. Carpenter), U.S.N.M., E. 3073, Adelie 

 Land, width at first syzygy 3.2 mm., tip of cirrus with 41 segments; e, same, longest 

 cirrus segment, b, S. antarctica, syntype, B.M., 88.11.9.34, width at first syzygy 

 3.2 mm., tip of cirrus with 31 segments;/, same, longest segment; i, same, proximal 

 part of PIS. c, Florometra mawsoni A. H. Clark, B.A.N.Z.A.R.E. station 105, width 

 at first syzygy 2.6 mm., tip of cirrus with 30 segments; g, same, longest segment. 

 d, F. mawsoni, syntype of F. antarctica John, Discovery Investigations station 599, 

 width at first syzygy 2.1 mm., tip of cirrus with 30 segments; h, same, longest seg- 

 ment; j, same, proximal part of P. 



The distal edges of the radials in the median line reach the rim of the centro- 

 dorsal, the radials being usually visible only in the interradial angles, The IBri 

 are short and bandlike, four or five tunes as broad as long, entirely free laterally, 

 more or less incised by a posterior projection from the axillaries, with which they form 

 on the articulation a moderately developed synarthrial tubercle. The IBr 2 are tri- 

 angular and nearly as long as broad; the anterior angle is rather strongly produced, and 

 truncated, and there is a rounded posterior projection of variable size, but never 

 very large, in the median portion of the proximal border incising the IBr^ 



The 10 arms are about 125 mm. long. The first brachial is wedge-shaped, 

 much longer exteriorly than interiorly, more or less deeply incised by a posterior 

 projection from the larger and irregularly quadrate second brachial. The first syzygial 

 pair (composed of brachials 3 + 4) is longer inwardly than outwardly, and somewhat 

 broader than the greater length. The following brachials are wedge-shaped, about 

 twice as broad as the greater length, becoming more obliquely wedge-shaped and after 

 the fifteenth short-triangular and twice as broad as long, shortening to about two and 

 a half times as broad as long after the thirtieth or at about the middle of the arm; 

 distally the length increases slightly. From the second syzygy onward the brachials 

 develop overlapping and finely serrate distal edges which become prominent after the 

 third syzygy. 



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

 tervals of 4 muscular articulations. 



P! and P 2 are about 22 mm. long, slender and flagellate, composed of about 60 

 short segments, which in the basal portion are about twice as broad as long, in the 

 central portion are somewhat broader than long, and in the terminal portion are about 

 as long as broad; these pinnules are strongly compressed, and the dorsal edges of the 



