58 



DISCOVERY REPORTS 



Eucampia (Molleria). 



Mangin has shown that the formation of a genus Molleria by Castracane, as distinct 

 from the genus Eucampia, Ehr., is not justified and has further shown by the discovery 

 of intermediate forms and forms having the characters of both, that the two " species ", 

 Eucampia balaustium, Castr., and Molleria antarctica, Castr., are really forms of one 



10,000 



□ 10.000-50,000 

 Q 50,000 -100,000 



I 100,000-500000 

 500.000-1.000,000 



Fig. 28. Distribution of Chaetoceros socialis round South Georgia in the December-January 1926-7 survey. 



For full explanation see legend of Fig. 16. 



species which he names Eucampia antarctica. Following Mangin we will refer to the 

 type balaustium and type molleria ; the former was found on each side of the island and 

 the latter only at the southern end of the island. Their distribution and numbers are 

 shown in Appendix I and Fig. 30. 



Fragilaria. 



F. antarctica, Castr., is one of the diatoms which occurred in considerable abundance. 

 Its distribution and numbers are shown in Appendix I and Fig. 31. It will be seen to 

 be absent from waters at the northern end of the island and most abundant where 

 the two streams of Weddell Sea and Bellingshausen Sea waters meet at the south-west 

 side of the island. 3,360,000 were estimated to be present at WS 44. It was also 



