1914] Esterly: Schizopoda of the San Diego Region 135 



There were no hauls made between 6 p.m. and 2 a.m., so we are 

 unable to account for the animals during that time, at least as far as 

 the horizontal hauls are concerned. As the table stands, however, it 

 contains some facts that are worth noting. It is to be suggested that 

 table 10 is to be interpreted as showing that Euphausia performs 

 vertical migrations. In the first place, more animals are obtained per 

 hour between 200 and 400 meters during the day than above that level 

 (section A, columns 1-3. line 6). Furthermore, as shown in section 

 B, column 1, the level above 100 meters is densely populated in the 

 early morning, whereas only four animals were taken there in 50 day 

 hauls (section A, column 1, line 5). As a matter of fact, all the hauls 

 set down in section B, column 1, were made between 18 and 37 meters. 

 It may be objected, of course, that there might have been about as 

 many animals between 9 and 100 meters from 6 a.m. to 6 p.m. as there 

 were from 2 a.m. to 6 a.m., but they were not captured at that level 

 during the day because they were able to see the nets and avoid them. 

 It must be admitted that this is possible and that our data from the 

 hauls with the Kofoid net do not show that it is not likely. The data 

 are deficient in that there are no hauls below 100 meters between 2 

 and 6 a.m. If the increase in the hourly average in column 1, section 

 B, over that in column 1, section A, is due to the migration of animals 

 from below into the upper level we should expect that at the time of 

 the increase above 100 meters, the population below that mark would 

 show a decrease. Obviously, it is not possible to show this in the 

 present state of our records. For all we can tell, there might be an 

 increase in the population below 100 meters in section B of the table, 

 instead of the decrease necessary to establish the fact of upward 

 migration. I believe, nevertheless, that the results indicated in table 

 10 are to be looked upon as due to a vertical movement of the animals. 

 This view is strengthened by an examination of the results of the 

 collections with the Nansen nets. As shown in table 4, only the winter 

 hauls are worth consideration. 



There were no hauls between 10 p.m. and 2 a.m., but the time from 

 6 to 10 p.m. is covered by thirteen hauls; this period was not covered 

 in table 10. The depths in tables 10 and 11 correspond as nearly as 

 possible, but it will be noted that there are considerable differences. 

 The day plurimum as shown by the Nansen hauls is located between 

 365 and 460 meters (table 11, section A, column 4, line 4) ; there were 

 fifty times as many animals obtained per meter between 460 and 365 



