DISTRIBUTION OF ANTARCTIC MACROPLANKTON 141 



The principal conclusion to be drawn from this table is that, while quite a different 

 type of plankton was taken on each of the three lines, the plankton at the individual 

 stations of each line was of the same type. In other words, the samples suggest that in 

 the eastern Scotia Sea the plankton is comparatively uniformly distributed, though its 

 constitution may differ at different times. Some species in these lines are more evenly 

 distributed than others. In the first line Calamus acatus is present at each station in 

 numbers which are very small for this species, and Thysanoessa increases steadily to the 

 westward. Calanus simillimns appears to do the same, while Pareuchaeta and Euphaiisia 

 frigida seem to become reduced, though allowance must be made for their diurnal 

 variations. The numbers of Calanus propinquus are more variable. The plankton re- 

 vealed by this line is thus not so uniform as it was in the eastern Weddell Sea (WS 544- 

 51), but it is more so than in the area to the east of the Sandwich group. In the second 

 line (WS 530-3) the numbers of Calanus acutus are very steady, Rhincalanus and the 

 Chaetognatha decrease to the westward, Euphaiisia superba, Thysanoessa and Euphausia 

 frigida are uniformly scarce, and the numbers of Calanus propinquus and Metridia show 

 no important fluctuations except for the large number of the latter taken at St. 533. 

 This, however, was something of the nature of a shoal. Thus the plankton taken on this 

 line was very uniform, and comparable to that of the eastern Weddell Sea. On the third 

 line also we have quite a uniform plankton. Allowance must be made for the alternate 

 day and night stations, and it will be seen that, apart from the exceptional catch of 

 Calanus acutus at St. 621, no important fluctuations occur in the numbers of each species. 



THE BELLINGSHAUSEN SEA 



In the Bellingshausen Sea two lines of stations have been worked westward from 

 Adelaide Island to a point beyond Peter 1 st Island. These were the ' Discovery II ' stations 

 in 1930-1 (Sts. 561-82, Fig. 14) and the 'William Scoresby' stations in 1929-30 (WS 

 502-8, Fig. 13). On both cruises the stations were taken at or near the ice-edge. There 

 have also been two shorter lines of stations running north-westwards from Adelaide 

 Island— that of the 'Discovery II' in 1930-1 (Sts. 583-97, Fig. 14) and that of the 

 'William Scoresby' in 1929-30 (WS 509-17, Fig. 13). Other stations in the Bellings- 

 hausen Sea lie up and down the coast of Adelaide Island, the Biscoe Islands and the 

 Palmer Archipelago. 



During the cruise of the 'Discovery II ' to the western Bellingshausen Sea twelve 

 stations were taken on the outward journey (Sts. 561-72) and ten on the return (Sts. 

 573-82), and these are arranged in their relative positions on the line in Table XI, as in 

 Table IX. 



Reference has already been made (p. 1 10) to the thin plankton of the eastern Bellings- 

 hausen Sea (near Adelaide Island, etc.), and this is clearly shown in Table XI at stations 

 east of St. 579. At the westerly stations the plankton tends to be rich, but there is great 

 variation in the size of the samples. However, the composition of the plankton is very 

 similar at these stations in spite of the fluctuations in abundance. Rhincalanus is usually 

 the dominant copepod, though Calanus acutus is more numerous at one or two stations, 



