42 University of California Publications in Zoology [ Vou. 14 
y gy 
The station having the smallest annual range of temperature is 
that nearest the Golden Gate (No. 4967), where the difference between 
the highest figure (at period III) and the lowest figure (at period VI) 
was 4°92 C. 
From this central region of the bay toward either end the magni- 
tude of the annual temperature range increases fairly rapidly. It 
is greatest at the mouth of the rivers (Carquinez Strait), where an 
annual range of 12°65 C wes found. At the southernmost station of 
the series (No. 5001) the range was found to be about 1.5 degrees less 
than this (11°18 C). 
Thus far, the charts have represented the regional distribution of 
temperatures, the stations being arranged serially along the horizontal 
axis. In the next two charts (figs. D and E), together with some 
others which will follow, the mean conditions for the bay as a whole 
are represented, the periods of work being arranged along the hori- 
zontal axis. 
Feb. Mar. Apr. May Jun. Jul Aug. Sept. Oct. Nov. Dec. dan, 
Fig. D. Annual temperature curves for entire bay. The continuous line 
is based on surface figures, the broken line on bottom ones. 
Figure D represents the temperature changes undergone in the 
course of an annual cycle, so far as may be judged from the single 
year covered by our principal series of observations (February, 1912, 
to January, 1913). In this chart the surface and bottom conditions 
have been depicted separately. The period of highest temperature 
was in July, when a mean temperature (mean of surface and bottom) 
of 16°68 C was obtained. The period of lowest temperature fell in 
January, when the mean figure was 8°33 C. There was thus an 
annual range, for the bay as a whole, of 8°35 C. 
