NOTES ON SPECIES 169 



Genus Amphiprora, Ehrenberg, 1830 

 Amphiprora sp. 



Another ice form observed rarely in the plankton. 



Family NITZSCHIACEAE, Schroder, 191 1 

 Genus Nitzschia, Hassal, 1845 

 Nitzschia closterium (Ehrb.), Wm. Sm. 

 Mangin, 19 15, p. 69, fig. 48. 



Confined to the far south in the Bellingshausen and Weddell Seas, close in to the land 

 or the fast-ice. Very rarely observed in small numbers in the older water farther north. 



Nitzschia seriata, Cleve. 



Lebour, 1930, p. 213, fig. 178. 



One of the most abundant of all the phytoplankton organisms in Antarctic surface 

 water of all types. A dominant species south of 63 ' in the Weddell Sea, and at several 

 stations in the western part of the Bellingshausen Sea. Frequently abundant in older 

 water farther north, especially just to the south of the Antarctic convergence in the 

 Scotia Sea at the beginning and end of the season. 



Nitzschia ? sigmoidea (Nitzsch), Wm. Sm. 

 Schiitt, 1896, fig. 259, p. 142. 



A form corresponding very closely to Schiitt's figure was encountered at one station 

 to the south-east of the South Sandwich Islands. 



Nitzschia sp. "A." 



This form occurred at several stations to the south-west of South Georgia in spring, 

 when the pack-ice lay far to the north, and also near the ice-bound Biscoe Islands to the 

 north-east of the Bellingshausen Sea. It formed branching colonies closely resembling 

 N.frigida, Grun., of the northern hemisphere. 



Nitzschia sp. 



An indeterminate form assigned to this genus was encountered at one station in sub- 

 Antarctic water. 



Class FLAGELLATA 



Sub-Class DINOFLAGELLATA 



Family GYMNODINIIDAE, Kofoid 



Genus Gymnodinium, Stein (emended Kofoid and Swezy) 



Gymnodinium (Pyrocystis) lunula f. lunula, Apstein. 

 Paulsen, 1908, p. iii, figs. 154, 155. 



Observed at two stations in the tropical South Atlantic. 



