lyo DISCOVERY REPORTS 



The oral pinnules were of i8 elongated segments and about 7 mm. long, but not one 

 of them is now complete. The following are the numbers of segments remaining in, and 

 the lengths of some of, the oral pinnules. In one specimen P3 is of 13 segments, 6-5 mm. 

 long; in a smaller specimen Pj is of 12 segments and 5 mm. long; and P^ and P, are of 

 12 segments, 6 mm. long. Some of the earlier genital pinnules are complete and are as 

 follows: P3 of about 9 segments, 4 mm. ; P4 similar in the same specimen, of 10 segments 

 and about 3 mm. long in another. The ambulacral furrow first appears on P5 . The distal 

 pinnules are of about 18 segments and about 6-5 mm. long. 



One of the specimens is a female. What Carpenter described as its "much swollen 

 ovarian sacs" are brood-pouches similar to those of the first specimen (from St. 156) 

 of var. antarctico. They lie alongside the ovaries on the third to fifth segments of the 

 genital pinnules. Each is split open for the whole of its length exposing the embryos 

 within. There may be up to 30, arranged in a single layer. They are irregularly spherical, 

 o- 1 8-0-24 ™"i. in diameter. They appear to be at the same and at an early state of de- 

 velopment, having no skeletal plates within them and no bands of cilia around them. 



There is no doubt that the specimens I have described above as the var. antarctica 

 are nearly related to P. longipinna. They are distinguished from it by the smaller number 

 of segments in the cirri and by the proportions of those segments ; by not having the 

 cirrus sockets arranged in such definite columns ; and by the less elongated segments of . 

 the oral pinnules. 



But the specimens of the var. antarctica from the two localities differ from one 

 another. The number of cirrus segments is smaller in those from St. 1948 than in that 

 from South Georgia. In the South Georgia specimen P3 is the first genital pinnule as 

 it is in two of the males from St. 1948; in the other male and in the female it is P2. 

 The elongated segments of the oral pinnules are more elongated in the South Georgia 

 specimen than in those from St. 1948, though less so than in P. longipinna. The shapes 

 of the brood-pouches and the arrangement of the embryos in them differ in the two 

 females ; the brood-pouch of the South Georgia specimen resembles that of the parent 

 species. 



It was long before I could decide how to treat the specimens. I hope this may be the 



best way. 



Phrixometra nutrix (Mortensen) (Plate IV, fig. 7) 



Thaumatometra nutrix Mortensen, 1918, pp. 15-18, figs. 14-15, pi. v. 1920, pp. 56-8, fig. 8, pi. xxviii. 

 St. 175. 2. iii. 27. Bransfield Strait, South Shetlands. 63° 17' 20" S, 59° 48' 15" W. 200 m. 

 Gear DLH. Bottom: mud, stones and gravel. One specimen. 



Description. Mortensen described this species from one poorly preserved female, 

 lacking any fully developed cirri, from the Burdwood Bank. The present specimen is 

 a male from the Bransfield Strait with most of its cirri present, fully developed and 

 complete. In other ways it is imperfect. No arm is complete: some are broken off at 

 the first syzygy, others at the second or third ; two are regenerated, one from the second 



