1912] Esterly: Copepoda of the San Diego Region 287 
I am unable to reconcile the discrepancies between the action 
of the two sorts of nets. It seems certain that the Kofoid net 
will give more reliable results and it is possible that if the 
vertical hauls were distributed evenly through the day and 
night the results of using them would be more in agreement 
with those obtained by the horizontal nets. It may be said 
that the plurimum with the vertical nets between 6 and 8 p.m. 
is overwhelmingly between 75 and 100 fathoms (this is not 
shown in table 14), while between 4 and 6 a.m. the plurimum 
is plainly between 50 and 75 fathoms. These regions corres- 
pond fairly well with the plurima at the same times as shown 
by the Kofoid net (see preceding paragraph). Furthermore, 
in table 14, line 9, columns CG and D, and H and I, it will be 
seen that the total number of animals and the number per 
fathom is the same for night and day hauls between 75 and 
50 fathoms. It is noticeable that the vertical hauls at night 
were made in very early evening (6-8 p.m. or early morning 
2-6 a.m.) and these are the times when the Kofoid net showed 
the maxima at 100 fathoms. It can at least be said that there 
is an indication in the data from the vertical nets of the 
same behavior on the part of the animals as is shown by the 
horizontal net. 
Although the distribution of the vertical closing hauls as to 
time of day is not all that can be desired, the evidence points 
toward a diurnal migration of the organisms. Inspection of 
table 14 shows that above 50 fathoms the numbers of animals 
taken are smaller by day and larger by night (columns C, D, 
H, I, lines 1-8). Below 50 fathoms the day numbers are larger 
than above that level (columns C and D, lines 1-8, 9-12). Ac- 
cordingly, we may take 50 fathoms as a sort of dividing line 
and arrange a table like that following, which is a summary 
of the data in table 14. 
TABLE 15 
Summary of results in table 14 
Specimens Total hauls Success. Frequency 
per fathom Hauls 
Day Night Day Night Day Night Day Night 
Between 0 and 50 fathoms 4.6 104 “122 ata) 425° 169) «34 46 
Between 50 and 200 fathoms 7.0 5.6 35 26 26 24 70 38698 
