UNEVENNESS OF OCEANIC PLANKTON 531 



largely on other food, possibly upon smaller species of copepod or younger stages which 

 pass through the mesh of the recorder. 



The young Euphausiacea were never abundant in the series. Isolated specimens of 

 Parathemisto, Euphausia triacantha and E. frigida were taken south of the Antarctic 

 convergence and E. spinifera to the north of it. 



Record 30 



Date: 12. vi. 27. 



Time: 1202-2050. 



Position: 39° 52' S, 5° 18' W to 39° 35' S, 3 33' W. 



Distance by ship's log: 81-9 miles. 



Record 3 1 

 Dates: 13-14. vi. 27. 

 Time: 2243-0930. 



Position: 38 21' S, o° 42$' E to 38° 4' S, 2 45' E. 

 Distance by ship's log: 107-8 miles. 



Record 32 



Date: 15. vi. 27. 



Time: 0955-2055. 



Position : 37 34' S, 6° 09' E to 36° 57' S, 8° 44!' E. 



Distance by ship's log: 108-7 m il es - 



Record 33 



Dates: 16-17. vi. 27. 



Time: 2300-1 100. 



Position: 35 28*' S, 13 o 9 \' E to 34 46 J S, i 5 ° 17!' E. 



Distance by ship's log: 124-1 miles. 



These four records were taken from the R.R.S. 'William Scoresby' on a voyage 

 across the South Atlantic Ocean between Gough Island and Cape Town. The out- 

 standing features are illustrated in Figs. 15 and 16. Throughout the series there is a 

 remarkable contrast between the abundance of Copepoda during the night and their 

 scarcity or absence during the day. This must undoubtedly be attributed to vertical 

 migration. Nevertheless, on top of these general migrational increases a number of 

 marked fluctuations in numbers are revealed. Limacina occurs in well separated zones 

 and small salps extend in a patch of some 36 miles but are taken nowhere else on the 

 records. The young Euphausiacea show increases during the night in records 30, 31 

 and 32, but in record 33 they are taken in larger numbers in the daytime. 



Record 34 



Date: 19. viii. 27. 



Time: 0930-1800. 



Position: 2 50' S, 8° 30' W to 2 49$' S, 9 25'-' W. 



Distance by ship's log: 40-7 miles. 



