28o DISCOVERY REPORTS 



Table 58. 16-20 mm. class. The 111 simultaneous samplings by the surface {0-5 m.) and oblique 

 {100-0 m.) stramin nets, the 102 instances zvhere the surface catch was the larger, or not the less, in the 

 upper part of the table, the nine instances where the oblique catch was the larger below. Night hauls in 

 roman type, day hauls in italics 



That our day and night surface gatherings of larvae and early adolescents and our night surface 

 gatherings of older adolescents and adults should so often be larger than our oblique gatherings is only 

 to be expected, since with a population such as this, the greater part concentrated at or near the 

 surface in a system of swarms, a net towed on the surface for half an hour is manifestly far more likely 

 to strike a swarm than one that is hauled, as the oblique net is, only for a few minutes through the 

 surface zone. Indeed, it is abundantly clear from Tables 57-9 that the oblique net must often break 

 surface in the ' voids ' or places of euphausian scarcity that separate the swarms. 



It is clear then from these tables that the more reliable estimate of the relative abundance of this 

 species in the plankton is to be obtained from the data provided by the surface nets and that the 

 distributional data as a whole will acquire increased validity if some correction be applied to the 



