PHYTOPLANKTON OF SOUTH GEORGIA 



37 



described. In both these cases Corethron was the dominant form. Elsewhere it might 

 be described as co-dominant with Thalassiothrix in a tongue of comparatively cold water 

 reaching right up the eastern side of the island, and originating at an indeterminate 

 distance to the south-east, as indicated by the first two stations worked on our way to 

 the South Sandwich Islands a fortnight later. 



The two dinoflagellates Peridinium antarcticum and Ceratium pentagonum f. grandis 



SCALE 



0-10000 

 1 10,000 — 100000 



1 100,000 —1,000,000 

 H 1.000,000—10,000,000 



> 10.000,000 



I 



HO^ 





.ci^. hq\ 



J> 



Fig. 13. The distribution of Thalassiothrix antarctica, South Georgia survey, January-February 1930. 



were very similarly distributed throughout the area (Figs. 15 and 16). Present in 

 moderate numbers at almost all the stations worked during the survey, they reached 

 their greatest abundance to the north of the island. Generally speaking, their abundant 

 occurrence was closely correlated with the highest surface temperatures, while the 

 diatoms, more particularly Thalassiothrix, reached their maximum in comparatively cold 

 water to the east. 



The distribution of the diatom Eiicampia antarctica is shown in Fig. 17. It will be 

 seen that except for two stations just to the north of Bird Island, it was found almost 



