2i6 DISCOVERY REPORTS 



period of poor standing crop in these latitudes. It is interesting in this respect, however, to note that 



King & Hida (1954, p. 49) remark upon similar latitudinal variations in range of data from the Pacific. 



As previously stated, it has been necessary to combine results from all sectors of the Southern 



Ocean in order to get sufficient observations in all latitudes. The hydrology of the area is such that 



WINTER (MAY- OCTOBER) 



IOOO-0 M 



29 O 

 26S 



TEMPERATURE GROUP 



Fig. 12. Comparison of the mean quantities of zooplankton between arbitrary temperature limits in winter and summer. 

 Results are given for the 100-0 m. horizon and for the whole water column sampled (1 000-0 m). The temperature is the mean 

 at each station for the 100-0 m. horizon. Numbers of observations are given in Table 6. 



latitude is not a very realistic scale on which to compare volumes, since the position of the Antarctic 

 Convergence — which is for many planktonic species a major influence upon their distribution — 

 varies in such a manner that two stations in the same latitude but in different longitudes may be in 

 quite different water masses or temperature zones. Thus in the meridian of 8o° W St. 989 is 6o° 38-6' S, 

 while in the meridian of o° St. 2320 is 61° io-6' S; both are in the same approximate latitude, but 

 the former is sub-Antarctic with a surface temperature of 3-43° C, while the latter is Antarctic with 



