100 University of California Publications in Zoology [ Vou. 14 
15.24, the annual mean for a station in Carquinez Strait, to 31.04, 
the mean for a station near the Golden Gate. The salinity was found 
to fall steadily from the ocean to the northern end. It was likewise 
found to fall somewhat as we passed to the southern arm of the bay, 
though rising slightly at the lower end. 
The highest single salinity figure recorded for the bay was 33.27, 
on October 12, 1912, at the station nearest the Golden Gate, the lowest 
being 3.25, on April 23, in Carquinez Strait. (See, however, the figures 
for March, 1914.) 
The seasonal means varied from 25.23, representing the mean 
salinity of the entire bay in the April-May period to 30.51, represent- 
ing the mean for the bay in October. The regional range was lowest 
in January (not in October, as might have been expected), highest at 
the time of the April-May observations. 
In considering all of these figures for salinity, it must be borne in 
mind that both years in which the observations were made were ones 
of very deficient rainfall. Supplementary data, obtained after the 
heavy precipitation of the winter of 1913-1914, indicate that, for the 
spring months, at least, the figures here presented are considerably 
higher than the average. 
13. The mean salinity figure for the surface samples was 26.77, 
that for the bottom samples being 28.19. This difference between 
surface and bottom was naturally highest where the waters of the 
rivers enter the bay, and lowest near the Golden Gate. 
14. Contrary to expectation, the mean salinity of water samples 
taken during the flood phase of the tide was appreciably and pretty 
constantly lower than that of samples taken during the ebb phase. 
This seeming paradox was explained by a consideration of our method 
of procedure in obtaining the water samples. These were commonly 
obtained early in the course of a given tidal phase, and early flood 
water is naturally less concentrated than early ebb water. 
15. Certain general relations were established between the salinity 
of the bay water and the recorded river flow and rainfall for the 
regions tributary thereto. Such relations were, however, ones which 
might have been predicted in advance. 
16. The salinity of the local ocean water, at ten stations, from 
ten to twenty-six nautical miles beyond the Golden Gate, was found, 
during late October and early November, to be 34.04. The observa- 
tions were, however, made early in the rainy season and at about the 
period of least river flow. In the spring, the discharge of the local 
