334 DISCOVERY REPORTS 



annual volume or activity of the bottom water flowing away from the Weddell Sea and the annual 

 abundance of the deep larvae that are encountered during the spawning season. It is interesting, 

 therefore, to record that (see again Fig. 82) Stations WS 197, WS 199 and WS 200 fell in 1928 

 and Station 133 1 in 1934, both years in which, as Fig. 81 shows, the activity of the bottom water 

 was apparently weak and the average catch of the deep larvae low. It may be, therefore, that the 

 apparent inactivity of the bottom water in these years resulted in the arrival of the deep larvae in 

 Weddell West at a later date than usual and that in consequence the development to the late Furcilia 

 state was correspondingly late. 



Elsewhere, outside the Weddell zone, the East Wind drift is without trace of a late Furcilia popula- 

 tion. Nor indeed could one be expected, since in these high latitudes, even in late April (p. 321, 

 Fig. 83), the larvae have still, it seems, not outgrown their Calyptopis phase. In the otherwise barren 

 West Wind drift the occurrence of very small numbers of late Furcilias may be noted at two stations 

 (both in April, one of them again at Station 861) south-east of Kerguelen, and the occurrence of a 

 minor (also April) concentration noted in the West Wind region of the Scotia Sea. In view of its 

 relatively great distance from the Weddell drift, to the western part of which the late Furcilias are 

 now principally confined, the Scotia Sea occurrence seems something of an anomaly. It might, how- 

 ever, like the Bellingshausen Sea-Drake Passage occurrences discussed on p. 315, have been of East 

 Wind origin, having sprung perhaps from a rising that took place somewhere to the south of Peter I 

 Island. In the heavily sampled region round South Georgia and in the equally heavily sampled 

 Bransfield Strait there has evidently been some little growth of the few early Furcilias already recorded 

 there, but as yet no large-scale incursion of late Furcilias into either locality. 



Since the earliest substantial rising of First Calyptopes was recorded on 18 January (p. 314, Fig. 77) 

 and the first substantial numbers of Furcilia 5 recorded between 18 and 26 March (Fig. 90), 

 the development from the First Calyptopis to the Fifth Furcilia stage in the Weddell drift would 

 appear at its fastest to be accomplished in from 60 to 70 days. From the results of the plankton 

 investigations of Heegaard (1948), in the Gullmar Fjord, Sweden, it appears that the corresponding 

 development in Meganyctiphanes norvegica takes from 42 to 49 days, a distinctly faster rate than I seem 

 to find in E. siiperba influenced perhaps by the fact that his specimens were taken in considerably 

 warmer conditions (4° C or higher) than are encountered in summer and autumn (p. 80, Table 6) in 

 the Weddell drift. 



May-June. The distribution of the late Furcilias in May and June is shown in Fig. 92, the 

 occurrences, all but one of very small numbers, emphasising, like the Calyptopes and early Furcilias 

 from the same stations, the importance of the Weddell stream and the seemingly abrupt termination 

 of its influence eastwards of 30° E. The principal concentrations of larvae in Weddell East, which is 

 virtually the only sector of the current in which we have observations at this time of the year, are still 

 (p. 318, Fig. 80) mainly in the early Furcilia state, or younger, and as yet only a very small per- 

 centage of individuals has moulted and advanced beyond the Third Furcilia stage. We have no 

 May-June observations in the Weddell stream farther west. The developmental condition of the 

 swarms encountered there in March and April, however (p. 321, Fig. 82 and p. 331, Fig. 90), 

 suggests that both in Weddell West and Weddell Middle the late Furcilias would now be found in 

 great abundance. They must also by now I think have arrived in quantity on the South Georgia 

 whaling grounds, for although our vertical nets (for May) reveal only negligible numbers there, 

 Hansen (1913) in June 1901 and again in June 1902, records 'numerous' to 'very large numbers' of 

 E. superba larvae, which Rustad (1930) suggests were very probably late Furcilia forms. 



In the East Wind drift the occurrence of a single Fourth Furcilia may be noted off Enderby 

 Land. It is likely, however, that under the now extensive ice-sheet there the principal concentrations 



