CIRCULATION OF THE MACROPLANKTON 405 



taken by the ' Discovery II ' in the western part of the Pacific sector of the Antarctic. In 

 both these localities the conditions are quite different from those in 8o° W. The posi- 

 tions of these stations are plotted in Figs. 8 and 9, and details of them are as follows: 



Winter stations 



WS254. 53 03' S, 46 58' W. 22. viii. 28. 



WS255. 53 23' S, 44 10' W. 22-23. viii. 28. 



Summer stations 

 WS315. 53 26' S, 43 49' W. 2. xii. 28. 

 WS316. 52 56' S, 46 26' W. 3. xii. 28. 



Winter stations 



950. 59 05' S, 163° 46' W. 7-8.ix.32. 



951. 6i°26'S, i6o°o3'W. 8. ix. 32. 



Summer stations 

 1271. 65 05' S, 166 08' W. 19. i. 34. 

 1273. 62 08' S, 168 59' W. 20. i. 34. 



Sts. WS 254 and WS 255 were included in a line of stations worked between South 

 Georgia and the Falkland Is. (that is in the north part of the Scotia Sea) in August, 1928, 

 and Sts. WS 315 and WS 3 16 were worked very near to them in the following December. 

 The two pairs of stations therefore are quite suitable for a comparison of winter and 

 summer distribution. Both of course are in Antarctic water. Sts. 950 and 951 were 

 included in a line running south eastwards from New Zealand in September, 1932, and 

 Sts. 1 27 1 and 1273, worked in January 1934 are the nearest summer stations in that part 

 of the Antarctic. (At St. 1272 the vertical 70-cm. nets were not used). 



The vertical distribution of Rhincalanus gigas, Eukrohnia hamata and Calanus acutus 

 at these stations is shown in Table XXI. In this table the left-hand station of each pair 

 is the more southerly one. 



It will be seen that in the north part of the Scotia Sea in winter (Sts. WS 255 and 2^4) 

 Rhincalanus gigas, as in 8o° W in winter, lay almost entirely in deep water below 250 m., 

 and the largest numbers occurred between 250 and 750 m. In summer (Sts. WS 315 

 and WS 316) there were very few in deep water. The vast majority were above the 

 250-m. level and by far the largest catch was taken between 50 and 100 m. The winter 

 distribution in the western Pacific (Sts. 950 and 951) were similar, large numbers being 

 taken below 250 m. and hardly any in shallow water. In summer here the species was 

 scarce at all depths at St. 1271, but at St. 1273 large numbers were taken only at the 

 surface. Thus everything points to an annual vertical migration of this species in the 

 Scotia Sea and the western Pacific similar to the annual migration which has been de- 

 monstrated in 8o° W. 



Similarly Eukrohnia hamata lies in deep water at Sts. WS 255 and 254 and in shallow 

 water at the corresponding summer stations. It is again in deep water at Sts. 951 and 

 950. At one of the summer stations (1 271) its return towards the surface is less apparent, 

 but at St. 1273 it was abundant at the surface and comparatively scarce in deep water. 



