RA Se) Po 
1912] Esterly: Copepoda of the San Diego Region 317 
and frequency occurred between 8 and 10 p.m., as is shown in 
figure 7. The temperature and salinities ranged from 13°8 to 
20°4, and from 33.539 to 33.704. 
HaPenceene ace 
6-8 8-10 10-12 12-2 
P.M. A.M. 
Pig. 7. Rhincalanus nasutus. Variations in numbers per ten hours of 
hauling at the surface at night up to 4 a.m. 
2-4 
The results of hauls made with the horizontal closing nets is 
shown in table 45. The abundance at 50-75 and at 200-250 
fathoms is the same during the day, but the frequency at the 
latter depth is greater (compare lines 2 and 4) ; it seems likely, 
therefore, that the center of migration is located between 200 and 
250 fathoms. There is very little evidence of an upward migra- 
tion at night unless the desertion of the 200-250 fathoms level 
at night may be so considered. 
TABLE 45 
Distribution of Rhincalanus nasutus as shown by hauls with the 
horizontal closing nets, day and night hauls compared 
A Cc D E F 
Total Successful Total Total Animals per Haul 
Depth hauls hauls hours animals 10-hr. haul frequency 
Day Night Day Night Day Night Day Night Day Night Day Night 
4-35 29 27 a aa 8.8 7.8 i aed a al 3°63 
50-75 12 8 0) 3.3 3.0 2 0 60 Sean0) 
100-160 8 11 Tineatl 2.7 4.0 oak 3 2 12 9 
200-250 6) 8} 20 3.2 1.6 PB ) 6x0 22 0 
300-550 “0 ie) 3.3 0.0 1 0 3 (0 14 0 
