i 4 4 DISCOVERY REPORTS 



It should be mentioned that the stations at the south-eastern end of the line (near 

 Adelaide Island) were a little closer together than those to the north-west (see Fig. 14, 

 inset A). 



The table shows the same thin plankton that was found at stations east of St. 579 in 

 Table XI. The poorest plankton of all is found in the middle, there is slightly more at 

 the inshore end (south-east) and the largest catches at the north-west end where indeed 

 one might expect to reach a region of richer plankton. The composition of the catches 

 must be regarded as quite uniform. Only Rhincalanus varies to some extent, but where 

 there are never more than a few hundred specimens in the samples, such fluctuations 

 cannot be of much significance. 



During her cruise in the Bellingshausen Sea the 'William Scoresby' also worked a 

 line of stations north-westwards from Adelaide Island (WS 509-17, February 1929-30, 

 Fig. 13, inset). This was a short line, however, and the stations were close together, so 

 that it is of less importance here than the 'Discovery II' line. It may be mentioned 

 that the catches were quite similar in size and composition to those in the Discovery 

 samples, and the plankton seemed quite uniform along the line except at WS515, 

 where a surprisingly large catch was taken in which Calonus acutus, C. propinquiis, 

 Metridia, Parathemisto and Thysanoessa numbered three or four hundred each. 



Other hauls taken in the Bellingshausen Sea include only some stations taken along 

 the coastal region between Adelaide Island and the South Shetlands. There were six 

 taken by the 'William Scoresby' at the beginning of January 1929-30 (WS 496-501, 

 Fig. 13), five taken by the 'Discovery II' at the end of December 1930-1 (Sts. 

 556-60, Fig. 14), and five more by the same ship late in January of the same season 

 (Sts. 598-603, Fig. 14). The samples taken at the ten stations of the 'Discovery II' 

 were all very small, averaging about 130 organisms per haul. By far the largest of these 

 was the catch taken at St. 598 which contained over 600 organisms of which Metridia 

 formed the majority. At three of the 'William Scoresby ' stations, however (WS 496, 

 497 and 501), quite large catches were taken, each containing several thousand 

 specimens of Calanus acirfus. None of the other species was very plentiful, but such 

 catches are very unusual in these coastal regions. 



It seems then that the eastern or coastal region of the Bellingshausen Sea is charac- 

 terized by a thin plankton of fairly uniform distribution, but that here and there one or 

 more species may become concentrated, as a result, perhaps, of some local peculiarity 

 in the hydrological conditions. 



THE ORKNEY-SHETLAND REGION 



In this section those stations will be briefly considered which lie in the vicinity of 

 the South Shetlands and South Orkneys and in the Bransfield Strait, a region charac- 

 terized, as already noted, by a general scarcity of plankton. 



In the Bransfield Strait three intensive surveys have been carried out, with lines of 

 stations at short intervals, and between the South Shetland Islands and the South 



