HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 327 



surprising to find that in both instances they are considerably more advanced than any that have so 

 far been recorded in April (p. 321, Fig. 83) from the East Wind drift itself. The most likely 

 explanation of this anomaly is that at some earlier stage in their development, probably shortly after 

 they reached the surface as First Calyptopes, they got carried away from the comparative darkness 

 of their ice-infested, diatom-poor southern habitat (see p. 351, Fig. 104) and, reaching a region of 

 higher photosynthetic values and better grazing, outgrew their contemporaries in higher latitudes. 

 These East Wind deflections could in fact be described as miniature Weddell drifts in which the larvae 

 develop at a rate broadly comparable with that in the major current. 



Apart from these isolated occurrences, it will be seen that the principal concentrations of the early 

 Furcilias in March and April are confined exclusively to the main east-flowing Weddell stream. 

 Outside this current, in the West Wind region of the Scotia Sea south of the Antarctic convergence, 

 there are three minor concentrations to be noted, two in March and one in April. Clearly again 

 (p. 316) these must have come from the west and in view of their age it is possible that they might 

 have had the same East Wind origin as that ascribed to the April concentration in the Drake Passage. 



May-June. The distribution of the early Furcilias in May and June (Fig. 88 ), like that of the 

 Calyptopis stages for the same period, again emphasises (though from the same stations) the import- 

 ance of the Weddell drift as a primary carrier of the larvae and a major instrument of their dispersal. 

 At the same time it is again worth noting that the pronounced local abundance of young Furcilias 

 revealed in this figure cannot, it seems, be other than real. For although varying observational density 

 in given areas may often provide a false impression of the true relative abundance of a species within 

 such areas, in this instance it obviously cannot, for as Fig. 88 shows our coverage of the circum- 

 polar sea for May and June is not only reasonably uniform (excluding the ice-covered East Wind zone) 

 but is everywhere so uniformly meagre that the heavy concentration of larvae we have recorded in 

 Weddell East, where virtually every surface net haul is positive, postulates a real and not merely an 

 apparent abundance there. 



Although the Calyptopes in Weddell East (p. 317, Figs. 79 and 80) survive in some measure 

 of abundance into June, the early Furcilias are now the dominant stage, a dominance indeed only 

 to be expected with the former fast outgrowing themselves and shortly about to disappear from the 

 plankton of this region. It seems fairly certain, too, having regard to the overall developmental 

 condition of the Weddell swarms in April (p. 321, Fig. 82), that had we observations to show it, 

 the whole of the Weddell stream from west to east would now be found to be carrying larvae pre- 

 dominantly in the early Furcilia stage. It is probable, too, that these stages have by now arrived in 

 mass on the South Georgia whaling grounds, for although our vertical observations it is true are too 

 few to show this conclusively, in four out of five horizontal towings made off the east side of the island 

 in late May 1927 Hardy and Gunther (1935, Appendix 11) record 'Cyrtopias' (= possibly Furcilias) 

 in moderate to substantial numbers. 



In the ice-covered East Wind zone on the other hand, it is unlikely as explained on p. 323 that the 

 young Furcilias can yet have appeared on any substantial scale. It is interesting, however, to record 

 that among the material brought back by the * Belgica ' expedition which wintered in the pack south- 

 west of Graham Land in 1898, Hansen (1908, p. 7, PI. i) reports that on 4 May a 'good number' 

 of larval E. superba, which from his excellent figures are clearly Furcilias 1-4, were taken in a plankton 

 haul in 70° 33' S, 89° 22' W, a position located well inside the East Wind drift and very close to the 

 point where it breaks away to form the Peter I Island cold tongue. This record is of great interest, 

 since it provides the only evidence we have as to what the real autumnal condition of the larvae in 

 these high latitudes might conceivably be. It need not, however, mean that these, mainly early, 

 Furcilias were at that time either dominant or even abundant there. A ' good number ' does not suggest 



