DISTRIBUTION OF YOUNG STAGES OF EUPHAUSIA SUPERBA iis 



greatest concentration of larvae was at St. 647, the one before that just mentioned; here 

 4279 MetanaupUi were taken. The distribution of the stations where MetanaupUi were 

 taken is shown in Fig, 32. 



VERTICAL DISTRIBUTION 



The majority of the larvae belonging to this stage were found in the two deepest nets 

 between 500 and 1000 m., although their occurrence is recorded also in the four upper 

 nets at certain stations. At St. 647, where the larvae occurred in greater abundance than 

 at all the other stations added together, they are entirely confined to depths between 500 



Fig. 32. Distribution of Metanauplius of Euphansta superba. 



and 1000 m. In areas of open water away from the influence of the ridge of the Scotia 

 Arc, and, in the case of St. 648, away from the influence of the Antarctic convergence, the 

 larvae are entirely restricted to depths below 500 m. It is at such depths that the bulk 

 of MetanaupUi are found, and it is important to consider the conditions of their 

 environment. 



They are found in the warm deep water and not in cold Antarctic surface water. The 

 properties of this warm deep-water layer are described by Deacon (1933, pp. 222 et seq.), 

 and it is not necessary to recapitulate them here beyond pointing out that he states that 

 the depth of the maximum temperature in 57° 30' S is 600 m. and of maximum salinity 

 700 m., and that the usual component of movement is from warm to cold regions and 

 not from cold to warm. 



Now if the temperature range within which Metanauplii were taken is examined, it 

 will be seen that although the larvae are occasionally found in water of temperature 

 below 0° C. they apparently favour the warmer water. Thus at St. 647 the range is be- 



15-2 



