1912] Esterly: Copepoda of the San Diego Region 311 
Euchirella rostrata.—Nineteen specimens were obtained in 
13 surface hauls. The number in night hauls (16) is five times as 
great as that in day hauls (3), and there are three times as many 
successful night as day hauls. The lowest and highest tempera- 
tures and salinities for the surface hauls taking the species are, 
respectively, 1629 and 2029, and 35.534 and 33.670. 
The center of migration (daylight plurimum) seems to be 
at about 200 fathoms, yet out of 8 hauls during the day at or 
below 100 fathoms, with the closing nets only one was success- 
ful, taking one animal; the other seven specimens were obtained 
above 100 fathoms, one by day and six by night, the latter 
being taken in six hauls. Evidently, the species moves upward 
at night if the numbers taken at the surface then as compared 
with those during the day can be taken as representative of 
the whole population. 
Gaidius pungens.—This species is one of the commonest in 
the hauls with closing nets, but extremely rare at the surface. 
It was taken there in only three hauls, all of which were in 
daylight. It was obtained in 12 hauls with the horizontal clos- 
ing nets and in 26 with the vertical nets; these took 148 and 
777 specimens respectively. The distribution of these specimens 
at different depths and at various times as shown by the hori- 
zontal closing nets is indicated in table 37 which follows. 
TABLE 37 
Distribution of Gaidius pungens as shown by hauls with the horizontal 
closing nets, day and night hauls compared 
B Cc D E EF 
Total Successful Total Total Animals per Haul 
Depth hauls hauls hours animals 10-hr. haul frequeney 
Day Night Day Night Day Night Day Night Day Night Day Night 
4-35 29 27 0 0 8.8 7.8 0 0 0 0 0 0 
50-75 12 8 1 1 3.3 3.0 1 2 3 6 8 12 
100-160 iste gal 2 2 2.7 4.0 55 4 203 14 25 18 
200-250 9 3 5 0 dee. U6 81 0 506 0 55 0 
300-550 7 0 1 0 3.3 0.0 75 0 18 0 14 0 
The region of greatest abundance is plainly between 200 
and 250 fathoms during the day. This level is deserted at 
night, when the region of greatest abundance is between 100 
