172 DISCOVERY REPORTS 



but the opposing spine, which is directed obliquely forwards, is weak. A few developing 

 cirri of the kind described and figured by Mortensen are present. 



The shapes of the radials and axillaries are as Mortensen describes them, but the 

 costals are more conspicuously narrower distally than proximally, and more deeply 

 incised by the axillaries, than he shows (Fig. ii b). The shapes of the lower and of the 

 distal brachials are shown in Fig. ii c; the latter are elongated. The distal edges of the 

 brachials beyond the first syzygy are raised and produced into short but stout spines. 



The first two segments of all the pinnules are short ; the remainder are elongated with 

 their distal edges flared out and produced into thorns. Pi is of 14 segments, about 5 mm. 

 long (Fig. 1 1 d). P, is a genital pinnule. On no arm does it consist of more than 9 

 segments or is it more than 4 mm. long, but on none is it complete ; it seems probable 

 that it was originally of 14 segments like Pi as Mortensen describes it. The large fusi- 

 form gonad begins on the third and hes along the fourth, fifth and sixth segments. 

 P3 is of 10 segments, 4-5 mm. P5 , of 1 1 segments and 4-5 mm. long, is the first to have 

 an ambulacral furrow. 



There are no gonads on the pinnules of the regenerated parts of the only two arms 

 which are nearly complete. The outer pinnules of these arms are of about twelve 

 segments. 



The disk is naked, the anal cone very high. 



Sacculi conspicuous, irregularly arranged on the lower part of the arms and the 

 genital pinnules, regularly arranged on the outer pinnules. 



In Mortensen's specimen there were no side- or cover-plates. Along the middle 

 segments of the outer pinnules of this Discovery specimen there are side- and cover- 

 plates, three pairs to each segment, but they are so reduced as to be simple and rod-like 

 (Fig. 1 1 e). 



The shapes of the ossicles of the division series and of the brachials and, above all, 

 of the cirri, of this species and the next and of P. hngipinna var. antarctica are so alike 

 that I think they ought to be placed in the same genus. For that reason I have removed 

 Mortensen's species, nutrix, from Thaumatometra to Phrixometra, and placed my new 

 species in the same genus. 



Phrixometra rayneri n.sp. (Plate IV, fig. 8) 



St. 160. 7. ii. 27. Near Shag Rocks. 53° 43' 40" S, 40° 57' W. 177 m. Gear DLH. Bottom: 

 grey mud, stones and rock. One specimen. 



Description. This is a small fragile species, and in the single specimen, which is a 

 male, some of the pinnules are damaged and most of the arms are broken. Two of the 

 arms are nearly complete and are about 20 mm. long. 



The centrodorsal is small, low and rounded; the dorsal pole is rather large and 

 rough. The ventral edge of the centrodorsal is produced into low corners interradially. 



