ITINERARY: THIRD COMMISSION 295 



Group V 

 Coscinodiscus spp. (oceanic). 



Small numbers of this genus occur in minor quantities in the open oceans throughout 



the year and are important in the scanty winter phytoplankton of the northern region. 



The same remarks apply to : 



Actinocyclus spp. (oceanic). 



Asteromphalus spp. (other than A. parvulus). 



These are most abundant at the time of the main increase in the Northern Region, 

 but most important in winter. A. hookerii Ehrenberg is numerous much farther south 

 than the others — A. regular is Karsten, A. roperianus Ralfs ex Pritchard, A. brookei 

 Bailey, and other still indeterminate forms. 



ITINERARIES OF THE PHYTOPLANKTON OBSERVATIONS 



DURING THE THIRD, FOURTH AND FIFTH COMMISSIONS 



OF THE R.R.S. 'DISCOVERY H' 



The positions of the stations at which phytoplankton observations were obtained 

 within the Antarctic zone, during the third commission of the R.R.S. 'Discovery 11', 

 are shown in Figs. 3 and 4. On Fig. 3 the boundaries of the biogeographical regions 

 and areas previously described are also shown. The first experiments with the Harvey 

 net were made in sub-Antarctic water on the outward voyage from Tristan da Cunha 

 to South Georgia, so that we were proficient in the use of the new methods by the time 

 the Antarctic convergence was reached a little to the north and east of the South 

 Georgia area. Here we found the main diatom increase near its peak and twelve hauls 

 obtained during 27 November-4 December 1933 yielded very high values. Proceeding 

 south-westwards across the Scotia Sea, and through the western end of Bransfield 

 Strait to 67° 45-3' S in approximately 80° W, much less phytoplankton was encountered. 

 One station off the Palmer Archipelago yielded a fairly rich haul, but on working up 

 the 80° W meridian the comparative poverty of the phytoplankton in the eastern South 

 Pacific area, in the middle of December, was very apparent. 



We next crossed the convergence about the time of the New Year and proceeded 

 westwards on a zigzag course along the Pacific ice-edge into the area north of the Ross 

 Sea, and up to New Zealand at the end of January 1934. This cruise yielded more 

 evidence of the poverty of the eastern South Pacific, and showed uniformly moderate 

 quantities of phytoplankton in the Southern Region increasing as we proceeded west- 

 wards. 



On the voyage southward from New Zealand, station work was precluded because of 

 the necessity for speed in making the rendezvous with Admiral Byrd's supply ship, the 

 'Bear of Oakland', to whom we were transporting an additional medical officer and 

 stores. Observations began again in the last week of February in 72° S in the Ross 



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