46 University of California Publications in Zoology [ Vou. 14 
The results of the second series of observations of this sort will 
be found in Appendix IT (station 5329), but the curves based upon 
these figures have not been reproduced. The conditions here repre- 
sented are difficult to interpret. There is to be distinguished a gen- 
eral, though quite irregular, fall of temperature for both surface and 
bottom water during the flood phase; while during the ebb there is 
a gradual rise for the bottom water along with a considerable fall for 
the surface. The mean figures for the respective phases of the tide 
are flood—surface 14°56, bottom 14°13; ebb—surface 14°08, bottom 
13°19. It is interesting that the mean of all these figures is 13299 C, 
while that for station 4967 (near this point) for the July period of 
the preceding year was 14°00 C. 
The conditions during a single tidal cycle are so complicated that 
a simple comparison between the temperatures or salinities recorded 
for any two consecutive phases of the tide is obviously unsafe. This 
is particularly true in such a ease as that last referred to, in which 
the change of level during the flood period was 5.6 feet, while during 
the sueceeding ebb period it was only 1.3 feet. 
Jon. Apr May = Jun Aug Sept Oct Nov. Dec Jon. 
Fig. G. Variations in the regional range of temperature during an annual 
eyele. The ordinates represent the differences between the highest and lowest 
temperatures occurring simultaneously in the bay at any given time of the year. 
Figure G indicates the regional range of temperature throughout 
the annual eyele. The ordinates in this chart represent the differences 
between the highest and lowest temperatures occurring simultaneously 
in the bay at any given time of the year. As in figures D and E, the 
abscissas represent time intervals. 
The temperature range will be seen to be greatest during the July 
period, when it was about 5° C, and least in the February period, 
when it was 0°8 C. In reality, we may distinguish in our curve two 
maxima (third and sixth periods) and two minima (first and fifth 
