114 DISCOVERY REPORTS 



from the station nearly three months later at which the last eggs were found, so that the 

 extended egg-laying period cannot be attributed to great difference in the locality from 

 which the plankton samples were taken. In E. stiperba, therefore, it may be concluded 

 from the available evidence that spawning is not restricted to one short period but is 

 diffused over most of the months of the southern summer. There are indications that 

 the greatest production of eggs is in November-December, but as regards abundance a 

 distorted impression is obtained because certain plankton stations were taken at times 

 and places close to each other while others were in these respects spaced widely apart. 



NAUPLII 



It is not possible to come to any definite conclusion regarding distribution of Nauplii 

 when dealing with such small numbers as were found in our plankton samples. Both ist 

 and 2nd Nauplii were taken only at stations from which eggs were also recorded, so that 

 the general remarks regarding the regional distribution of eggs apply equally to the 

 Nauplii. 



Both the ist Nauplii were found below loo m., the one in the 250-ioo-m. net and the 

 other in the 750-500-m. net. It may be noted, too, that both Ruud's records are from 

 nets fishing in subsurface water. 



At three stations the 2nd Nauplii were in the 250-ioo-m. net, at three in the 500- 

 250-m. net, and the remaining one was in the 750-500-m. net. There is no record from 

 above 100 m. At two of the three stations where the Nauplii occurred in the 250- 

 loo-m. net eggs were found in the shallower nets, and it is possible that the Nauplii de- 

 veloped from such eggs. 



As mentioned above, the rarity of ist and 2nd Nauplii and the smallness of the num- 

 ber where records exist may indicate that these stages are passed through very rapidly in 

 this species, as in other euphausiids where the development is known (vide Lebour, 

 1926 c, pp. 520, 521). 



In the 1929-30 season all the 2nd Nauplii were taken in the second half of November, 

 and in the 1930-1 season in the latter part of December. They were not found outside 

 the range of the spawning period. 



METANAUPLIUS 

 REGIONAL DISTRIBUTION 



The distribution of the bulk of the Metanauplii differs in a marked manner from 

 that of the eggs. The latter were concentrated within the Bransfield Strait, but, with the 

 exception of those taken at St. 639, all the Metanauplii were taken north of the ridge 

 formed by the Scotia Arc, and the exception accounts for two only out of a recorded 

 total of over 4000 of this stage. Within the area of their distribution in the Scotia Sea 

 this stage is found in the north-east at St. WS 197, not far distant from South Georgia. 

 At this station 115 Metanauplii were taken between 1000 and 750 m. In the north-west 

 they were found as far north of the South Shetlands as the vicinity of the Antarctic 

 convergence (St. 646) from surface down to 500 m. to the number of fifty-six. The 



