286 DISCOVERY REPORTS 



Up to the end of June, and by three-monthly steps thereafter, the individual months, however, being 

 distinguished by appropriate symbols, they show, first the distribution of the eggs from November 

 to April, followed by that of the deep living forms, the Second Nauplii, Metanauplii and First 

 Calyptopes, for the same period. Then come the charts showing the distribution of the grouped 

 surface dwellers, first that of the three Calyptopes from November to June, then that of the early 

 Furcilias from January to June and finally that of the late Furcilias from March to December. The 

 plan in short constitutes an attempt to survey in as orderly a manner as possible the whole period 

 of the larval existence in the plankton, beginning with the time when the eggs first appear and ending 

 with that, more than a year later, when, in the Weddell drift at least,^ our townets have shown, 

 the last few Sixth Furcilias^ surviving from the protracted spawning season moult and become 

 adolescent. 



The four bi-monthly sets of charts portraying in turn the distribution of (a) the eggs, (b) the deep- 

 sited Nauplii, Metanauplii and First Calyptopes, (c) the shallow living First to Third Calyptopes, 

 and (d) the shallow living First to Third Furcilias, are severally followed by composite end-charts 

 showing, by monthly symbols, the gross distribution of these stages, or more correctly groups of 

 stages, throughout their protracted life-span in the plankton. A similar end-chart concludes the 

 bi-monthly and tri-monthly series presenting (e) the distribution of the late Furcilias. The main 

 purpose of these charts, it will be seen, is to show at a glance and on a single page some rather striking 

 features of the larval distribution and its dynamics, which, although already apparent, are not so 

 obviously apparent, in the serial presentation of the data that precedes them. 



The detailed presentation of the data just described is followed by a summarised version presented 

 on two groups of charts, the first showing the bi-monthly distribution and relative abundance of the 

 total eggs and larvae (the latter combining both deep and shallow living forms) from November 

 to April, the second the bi-monthly distribution and relative abundance of the total shallow living 

 larvae from January to June. In regard to the second group, it will be seen, charts of the distribu- 

 tion and relative abundance of the total surface population will in certain cases already have been 

 presented in the detailed series, the total surface larvae for November-December, for instance, 

 when the eggs first appear, being represented by the Calyptopes alone and the total surface larvae 

 during the following winter and spring (July to December) represented exclusively by the late 

 Furcilias. 



The distribution of the larvae based on the vertical data ends with a single chart showing the gross 

 or absolute distribution of the total egg and larval population all the year round, wherever and when- 

 ever, that is to say, it has been encountered in the vertical nets. In other words it ends with a picture 

 which constitutes the record of the horizontal distribution and relative abundance of the eggs and 

 larvae, the latter regardless of stage, that has been revealed by the whole series of vertical net samples 

 examined since these investigations first began. 



The charts based on the gatherings of the towed stramin nets follow each other on much the same 

 lines except that, as already noted, in marshalling the data the year has been divided into three- 

 monthly, or seasonal, periods throughout. They deal first with the distribution and relative abundance 



• Actually in the far colder conditions of the highest East Wind latitudes we have explored our stramin nets show 

 (p. 372, Fig. 120) that among the slow-growing, late-spawning population there some Sixth Furcilias do persist without 

 moulting over December, surviving in this state throughout January and February, and even into early March of the 

 following year. 



^ The recording of 'very large numbers' (p. 138) of Sixth Furcilias from the stomachs of blue and fin whales 

 examined in the late spring of the pelagic season of 1939-40 suggests, however, that in certain, possibly exceptional 

 years, the last larval stage may survive in Weddell East in some considerable measure of abundance until the second half 

 of December. 



