3i8 DISCOVERY REPORTS 



high southern region of larval abundance in the East Wind zone, covered for the most part by a great 

 ice-sheet, is everywhere, or virtually everyw^here, inaccessible^ and from now until January of the 

 following year the facts of the distribution can only be determined with certainty for such northerly 

 and gradually decreasing parts of the circumpolar sea as continue to remain ice free, the situation 

 in the East Wind drift becoming largely a matter for inference or conjecture. 



Taking first what is apparent, the situation in the ice-free north, it will be seen that although our 

 overall sampling of the circumpolar sea in May-June is uniformly meagre, more meagre in fact by 

 far than at any other time covered by our observations, it nevertheless still emphasises the importance 

 of the Weddell drift as the primary carrier of these now exclusively surface forms and their paramount 



MONTH 



WO"E- 



LONGITUDE 

 DAY 



STATION 

 FURCILIA 6 

 5 



CAL 3 

 2 

 I 

 DEEP LARVAE 



MAY 



JUNE 



-30E 



ir 17" 20" 24° O0° 00° 08° 17° 18° 18° 



I 2341 2589 lO 



1354 1355 1356 1357 1779 1781 1785 I790 1792 1794 



+ 



^411 ""' ilUo I T 



MONTH 



LONGITUDE 

 DAY 

 STATION 

 6 FURCILIA 

 5 

 4 

 3 



DEEP LARVAE 



Fig. 8o. Developmental condition of surface larvae in Weddell East in May and June. 



instrument of dispersal in these low latitudes. The situation in fact is even more striking than Fig. 79 

 reveals, for as will be seen later (p. 328, Fig. 88 and p. 348, Fig. 102), at all but one- of the fifteen 

 stations made in Weddell Middle and Weddell East at this time, surface larvae in one developmental phase 

 or another were encountered, for the most part in very substantial numbers. Compare with this the 

 larval barrenness encountered, for instance, between meridians 1 20° and 1 80° E, where our observational 

 coverage in May and June is actually heavier (in the West Wind drift) than in the Weddell zone. 



In Weddell East it will be seen the significant occurrences of Calyptopes are all in June, there being 

 in fact only one negligible occurrence of this developmental phase there in May, the majority of the 

 larvae encountered then, as Fig. 80 shows, having already reached a dominantly Second Furcilia 

 stage. Various reasons, however, might be put forward to explain this seemingly unnatural situation. 

 The observations for May-June in this sector were made in different years, the May stations in 1934, 

 the June stations in 1936, and it could well be that the 1934 larvae, as they drifted from the west, 

 encountered better feeding than the larvae of two years later and so, perhaps outgrowing their Calyp- 

 topis state at a somewhat faster rate than usual, arrived in Weddell East in a more advanced condition 

 than the majority of them seem to have done in 1936. 



In any event, in the investigation of such a complex thing as this, the dynamics of the distribution 

 of a heterogeneous system of larval swarms subject to the vagaries not only of a surface stream, but 

 of a bottom current and crosswise intermediate current as well, it is not surprising that the overall 



' Inaccessible from the north or seaward, not necessarily, however, from the continental land. It is now known that in at 

 least some parts of Antarctica, the near coastal waters of the East Wind zone may from time to time be surprisingly open even j 

 in the depth of winter. Fuchs (1958), describing the conditions at Shackleton Base in the winter of 1957, gives a very clear 

 picture of how open they can sometimes be. 'To our surprise', he writes, 'the movement of the pack ice under the influence 

 of the westerly current maintained constantly changing leads of open water. Occasionally a strong blow from the south would 

 drive the pack out of sight, so that all through the winter there were periods when open water extended many miles to east 

 and west of Shackleton'. Similar winter conditions have recently been reported between 45° and 80° E (Mellor, 1959). 



Priestley (1914), I find, records open water from shore to horizon off the Victoria Land coast in 75° S on midwinter's day. 



2 A northerly station (p. 328, Fig. 88) that might not in fact have been located in the Weddell drift at all. 



