300 University of California Publications in Zoology \Vou.9 
It may be that the animals really are less abundant at those 
temperatures than at the others as a rule, but we have hardly 
enough data for more than a suggestion to that effect. 
The effect of salinity on the distribution of Hucalanus at 
the surface can be determined from only 14 hauls. More than 
half of these hauls were made between 4 and 10 p.m., this being 
the time when the animals are most abundant at the surface 
anyway. This small number of hauls does not show that there 
is any connection between the salinity of the water and abund- 
ance; the limits are 33.534 and 34.069. A larger number of 
collections ought to be available if we are to have a reasonable 
basis for any conclusion. Farran (1910, p. 93) gives a sum- 
mary of the occurrence and distribution of Eucalanus as de- 
rived from the records of the International Council. 
DistripuTION OF Metridia lucens 
This species is the third most abundant in the San Diego 
region. It was taken in a much smaller number of hauls than 
Calanus or Eucalanus, but certain facets about its distribution 
seem clear. The distribution of this species at the surface is 
shown in table 26, which follows. 
TABLE 26 
Distribution of Metridia lucens at the surface in two-hour periods 
Time of No. of hauls No. of hours No. of animals Frequency 
day Total Suecess. Total Suecess. Total Perhour Haul Time 
a.m. A B Cc D E EF G H 
iB 6-8 35 1 27.2 0.62 42 1.5 3 2 
2. 8-10 21 2 20.2 2.3 2 0.1 9.6 11 
3. 10-12 14 0 9.8 0.0 0 0.0 0 0 
p.m. 
4. 12-2 14 0 9.0 0.0 0 0.0 0 0 
5. 2-4 14 0 11.1 0.0 0 0.0 0 0 
6. 4-6 13 1 9.9 0.6 6 0.7 8 6 
7 6-8 30 1 20.0 0.7 i 0.05 3 3 
8. 8-10 8 4 4.4 2.4 228 52.0 50 55 
9 10-12 1 1 2.8 2.8 31900 11380.0 100 100 
a.m. 
10. 12-2 3 3 2.6 2.6 3401 1310.0 100 100 
11. 2-4 8 6 12.0 9.4 2124 177.0 75 78 
12. 4-6 41 9 26.6 a 486 17.6 22 22 
