42 DISCOVERY REPORTS 



DINOFLAGELLATA 



Peridinium antarcticum, Schimper. Peridinium spp. 



P. castaneiforme, Mangin?. Dinophysis ovum, Schiitt. 



P. depressum, Bail. D. tuberculata, Mangin. 



P. elegans, CI. (var. Karsten). Ceratium pentagonum, Gourret, f. longisetum and 



P. minutissimum, Mangin. i.grandis. 



P. pentagonum, Gran?. C. gibberum, Gourret?. 



P. turbinatum, Mangin. C. tripos atlantica, f. neglecta, Ostenfeld (Paulsen). 



PROTOCOCCOIDEAE 

 Halosphaera viridis, Schmitz. 



CHRYSOMONADINEAE 



Phaeocystis sp. Seep. 64. 



SILICOFLAGELLATA 

 Distephanus speculum (Ehr.), Haeckel. 

 Distephanus sp. 



DISTRIBUTION 



DIATOMACEA 



Melosira. 



The two species of Melosira met with have only been recorded at four stations and 

 in very small numbers. M. hyalina, Karsten, was found at WS 34, 40 and 43 , and 

 M. sphaerica, Karsten, only at WS 43. It is of interest, however, that all were taken in a 

 small area at the south end of South Georgia, in surface water of Weddell Sea origin. 

 M. sol (Ehr.) Kuetz, which Mangin (19 15) regards as a very characteristic Antarctic 

 species, was not met with in the present survey. 



Coscinodiscus. 



Of the sixteen different species recorded, Coscinodiscus bouvet, Karsten, C. ker- 

 guelenensis, Karsten, C. oppositus, Karsten?, and C. lineatus, Erh., occurred in the largest 

 numbers. 



C. bouvet. This diatom was widely distributed round South Georgia — but occurred 

 in larger numbers on the south and east than on the western side. It was not recorded 

 between South Georgia and the Falkland Islands, nor from the N 70 V samples taken 

 between Tristan da Cunha and South Georgia. It would appear to be a true Antarctic 

 diatom. Its distribution and numbers as sampled by the N 50 V net are shown in 

 Appendix I and Fig. 16. It was also taken in large numbers by the N 70 V net, the 

 samples from which yielded interesting information regarding its vertical distribution. 

 At many stations they showed that more were to be found at levels below a depth of 

 100 m. than above it; they appeared to be gradually sinking and dying — the remnants, 

 no doubt, of a heavy crop which had previously existed in the upper layers. Mangin 

 (19 1 5) has already shown that this species is characteristic of the Antarctic spring, 

 occurring in large numbers from October to December, but declining in December 



