316 University of California Publications in Zoology (Vou.9 
plurimum is between 200 and 250 fathoms (line 4). This is 
also the location of the region of greatest abundance at night 
(column E), but the number of animals is much smaller at 
night; moreover, the animals were taken above 100 fathoms (line 
1) only at night. 
TABLE 43 
Distribution of Pleuromamma quadrungulata as shown by hauls with the 
horizontal closing nets, day and night hauls compared 
A B C 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 Oo} 3 8.8 7.8 07 6 017 (al 
50-75 12 8 0 0 3:3 713.0 0 0 0 0 0 0 
100-160 Sila 2 Ht 20 4:0 8 4 29 10 25 9 
200-250 9 3 5 u 38.2 1.6 28 2 80 12 5o 33 
300-550 he MY) 3460 3.2 1.6 60) LSS 43 0 
The vertical closing hauls (table 44) did not take the animals 
above 100 fathoms (lines 1 and 2), and there is a marked reduc- 
tion in the numbers taken below 100 fathoms at night as com- 
pared with day. This is some indication of an upward migration 
at night, but it is difficult to say in what degree the scarcity 
in deep water at night is due to lack of hauling. 
TABLE 44 
Distribution of Plewromamma quadrungulata as shown by hauls with 
the vertical closing nets, day and night hauls compared 
A B Cc D E 
Total Successful Total Animals per Haul 
Depth hauls hauls animals 100-f. haul frequency 
Day Night Day Night Day Night Day Night Day Night 
is 40-0 106 100 0 0 0 0 0 0 0 0 
2. 100-40 39 = 384 0 0 0 0 0 0 0 0 
By 200-100 12 if 5 4 27 13 27 13 41 57 
4. 250-200 6 1 6 al 154 1 208 2 100 100 
5. 300-250 4 1 3 1 75 1 150 2 75 100 
Rhincalanus nasutus—These copepods appeared in eleven 
surface hauls, of which nine were made during the night and con- 
tained 46 animals out of a total of 54. The maximum abundance 
