PHYTOPLANKTON OF THE WEDDELL SEA AREA 



107 



to occur in the Weddell Sea remains fairly distinctive in the far south, where the water 

 flows in from the east, the degree to which this distinction is retained as the water flows 

 out to the north-west is subject to both seasonal changes and to considerable fluctua- 

 tions from season to season. This being so, a consideration of all the sixty-one hauls 

 examined from the area should form a better basis of comparison with other areas 

 studied during the same period than any of the individual series of observations pre- 

 viously described. The following list of all the categories of phytoplankton organisms 

 recognized at these stations, arranged in order of their total abundance, and showing 

 also the number of stations at which each occurred, should render such a comparison 

 possible, always provided that certain minor anomalies due to the different seasons at 

 which the collections were made are carefully borne in mind. The more important of 

 these are indicated subsequently. 



Chaetoceros criophilum (53) 

 Rhizosolenia styliformis (51) 

 Nitzschia seriata (38) 

 Corethron valdiviae (56) 

 Fragilaria atUarctica (45) 

 Corethron valdiviae* (g) 

 Chaetoceros neglectits (38) 

 Thalassiosira antarctica (43) 

 Chaetoceros dichaeta (48) 

 Thalassiothrix antarctica (26) 

 Nitzschia closterium (11) 

 Rhizosolenia alata (47) 

 Dactyliosolen antarcticiis (16) 

 Synedra spathulata (19) 

 Chaetoceros atlanticus (14) 

 Silicoflagellata (28) 

 Biddulphia striata (16) 

 Eucampia antarctica (23) 

 Coscinodiscus botivet (16) 

 Chaetoceros schimperiamis (21) 

 Rhizosolenia bidens (i) 

 Coscinodiscus spp. (24) 

 Chaetoceros ? didymum (i) 

 Fragilaria antarctica f. 



boiivet (8) 

 Rhizosolenia truncata (20) 

 Dactyliosolen laevis (5) 

 Peridiniinn antarcticum (10) 

 Rhizosolenia chtinnii (2) 

 Navicula oceanica (i) 

 Leptocylindrits sp. (15) 

 Asteromphaliis regiilaris (13) 

 Melosira sol {1) 

 Peridinium spp. (12) 



In addition to the forms listed Chaetoceros socialis was taken in four hauls in un- 

 countable colonies, and would certainly have occupied an important position in the list 



14-2 



