PHYTOPLANKTON OF SOUTH GEORGIA 



53 



The large species Ch. criophilum, on the other hand (Fig. 22), was equally abundant 

 in both types of Weddell Sea water and least numerous to the north and north- 

 west where the influence of surface water from the Bellingshausen Sea made itself 

 felt. Whereas in the extremely rich hauls in the western Weddell Sea water, Ch. 

 criophilum, though abundant, was surpassed in numbers by the small forms mentioned 



Fig. 20. The distribution of Thalassiosira antarctica, South Georgia survey, November 1930. i = one 



million. 



above, in the moderately heavy catches in surface water of the eastern Weddell Sea 

 type it was the dominant form, as will have been seen from the percentages already dis- 

 cussed. This form reached its maximum for the survey in the comparatively old eastern 

 Weddell Sea water on the Larsen line. 



The distribution of Corethron valdiviae (Fig. 23) on this survey was very interesting. 

 In strong contrast to the summer survey previously described, the spineless chain form 

 was comparatively rare, the normal spiny form being present in moderate numbers in 

 all three types of surface water, and very abundant in the old mixed water to the extreme 

 north, and in the eddy close inshore off the north-east coast. Most of the individual 



