90 



DISCOVERY REPORTS 



therefore been adopted in the construction of the curves. These figures are given in 

 Table I, p. 95. 



The following pages contain notes on the variation of individual species. It has 

 already been mentioned that during a cruise of the 'Discovery II' a 24-hour station, 

 461, was worked south of Bouvet Island. At this station seven flights, each of six oblique 

 closing 1 m. nets, were towed every four hours at a series of depths down to about 

 700 m., and I have made a preliminary analysis of the samples. Although the present 

 paper is really concerned with the routine N100B samples, it will perhaps be per- 



00 04 08 12 16 20 00 04 08 



20- 



00 04 08 12 IB 20 00 04 08 



00 04 03 12 16 20 00 04 08 



00 04 08 12 16 20 00 04 OS 



00 04 08 12 16 20 00 04 08 



00 04 08 12 16 20 00 04 08 



00 04 08 12 16 20 00 04 08 



00 04 08 12 16 20 00 04 08 



00 04 08 12 16 20 00 04 06 



Fig. 20. Diurnal variations of macroplankton species (see legend to Fig. 18). 



missible to refer here and there to the results of St. 461 in so far as they apply to the 

 results shown in the table on p. 95. There is also a line of stations (618-25) at which the 

 net was hauled twice a day at about 10 a.m. and 10 p.m. through a region of uniform 

 plankton, and these constitute a useful piece of independent evidence. 



Diphyes antarctica (Fig. 20). The material is limited, but it is enough to show that there 

 is no significant variation. Specimens taken at St. 46 1 show no apparent vertical migration. 



Dimophyes arctica (Fig. 20). The curve for this species is unreliable, not so much be- 

 cause the species is uncommon north of 6o° S as because it occurs in sharply fluctuating 

 numbers. Thus the peak at 0400 is due to only two stations at which the species appeared 

 in larger numbers than usual. The instances of its occurrence are quite evenly distributed 



