DISTRIBUTION OF ANTARCTIC MACROPLANKTON 



i °S 



of those species which show a clear limitation of distribution. For instance, no specimen 

 of Euphausia vallentini has been taken at any station on the south side of line No. 4, and 

 none of Diphyes antarctica to the north of line No. 1. Euphausia superba may be found 

 in large numbers anywhere south of line No. 1, but is very rare to the north of it. It 

 will be seen that the majority of these lines also run roughly parallel to the direction of 

 drift, and indeed it would be surprising if they did not. It is one thing, of course, to say 



Fig. 21. Apparent distributional limits of 

 macroplankton species. 



1, Northern limit of Diphyes antarctica and normal 

 northern limit of Euphausia superba. 



2, Northern limit of Sibogita borchgrevinki. 



3, Northern limit of pelagic Eusirus antarcticus. 



4, Southern limit of Euphausia vallentini. 

 Northern limit of Auricularia antarctica. 



6, Southern limit of Euphausia triacantha. 



7, Southern limit of Candacia sp. 



8, Southern limit of Limacina balea. 



9, Southern limit of Calanus simillimus. 



io, Southern limit of Pleuromamma robusta and northern limit of Haloptilus ocellatus. 



that a species has not been found to the north or to the south of a particular line, and 

 another thing to say that it never occurs there. It must be emphasized therefore that 

 the lines shown on this chart are tentative. The utmost that can be inferred with 

 certainty is that there is a belt of change between South Georgia and the South Shetland 

 Islands. That is to say, an observer moving in a north-easterly direction in this part of 

 the Antarctic water would find few qualitative changes in the plankton, whereas if he 



