RHINCALANUS GIGAS 



299 



ance in sub-Antarctic water. During December, January or February, therefore, some 

 change apparently occurred in the copepod fauna involving the disappearance of Rhin- 

 calanus from the surface 250 m. in sub- Antarctic water. Further evidence of this change, 

 limiting the northward range of Rhincolanns, is to be found on the line from South 

 Georgia to South Africa at the end of the season (Fig. 11): 



* Upper net only. 



The above figures show, additionally, that on both sides of the convergence a far 

 more pronounced diminution of R. gigas had taken place by the end of February north- 

 east of South Georgia than had taken place by the middle of the month west of the island. 



Around the Antarctic Continent, April to October (Table III c) 



During the winter months, around the Antarctic Continent, we find that the con- 

 vergence continues to limit the distribution of R. gigas northwards, and that the species 

 is not found in sub-Antarctic water except in very small numbers (Table III t and 

 Fig. 11). The condition found in February between the Falkland Islands and South 

 Georgia and north-east of South Georgia thus appears to represent the winter condition 

 of the distribution of the species. 



The numbers of individuals taken on the circum-Antarctic lines of stations were very 

 much smaller than during the summer in the Falkland Sector. Only at one station (852) 

 on the Cape Town-Enderby Land line and at two stations on the Enderby Land- 

 Fremantle line (857 and 862), did the combined hauls amount to more than 1000 

 individuals (Fig. 11). 



On the line taken at the end of May from Fremantle to the ice-edge, and from the 

 ice-edge to Melbourne (Fig. 11), the catches were very small indeed, except at the most 

 southerly station (887) at the pack-ice edge south of Australia, where comparatively 

 large numbers (587) of young forms and nauplii were taken. A catch of more than 100 

 individuals was taken at St. 883, immediately south of the convergence between Fre- 

 mantle and the ice-edge, and of more than 250 individuals immediately south of the 

 convergence on the line from the ice-edge to Melbourne. Elsewhere on these two lines 

 the catches amounted to less than 100 individuals. 



At the end of June, when returning from Melbourne to the ice-edge south of the 

 Tasman Sea, the catches at the four stations (903-6) were extremely small, but again 

 a catch of more than 100 individuals was taken at the station (904) immediately south 

 of the convergence (Fig. 11). On the line from the ice-edge up to New Zealand Rhin- 

 calamis had almost disappeared from the catches, but here also the greatest number 

 (more than 25 individuals) was taken at the station (919) just south of the convergence. 



