1914) Sumner, et al.: Physical Conditions in San Francisco Bay 9 
plotting the distribution of species or of physical conditions was like- 
wise prepared by the draughtsman of the Bureau, and an edition of 
one thousand was printed at the Government Printing Office. 
The early publication of the results thus far obtained upon the 
physical conditions encountered in San Francisco Bay is regarded 
as important as an aid to those engaged in the study of the various 
organisms collected in the course of the present survey. Since the 
chief value of such studies lies in the light whieh they may throw 
upon the distribution of species—economie and otherwise—it is of 
the utmost importance for us to discover the various physical factors 
which may be responsible for the occurrence of these species in a 
given locality. That definite correlations actually exist between phys- 
ical conditions and the distribution of species is a mere platitude to 
zoologists, but it is equally true that in comparatively few cases do 
we know the factors which are actually responsible for limiting the 
range of a given form. Much light may sometimes be thrown upon 
this subject by the method of carefully plotting the distribution pat- 
terns of various species within an area in which the physical conditions 
are fairly well known (see Sumner, Osburn, Cole, and Davis. 1913). 
In the ease of all such undertakings as the present, any results 
of value which are obtained must be credited to the united efforts of 
a large number of persons. This number is unfortunately too great 
in the present instance to permit of the names of all of them appearing 
on the title page of this report. A large share of credit for whatever 
success has attended our efforts is due to the naval officers of the 
‘* Albatross’’, particularly to the successive commanders, Commander 
G. H. Burrage and, throughout a much greater part of the time, Lieu- 
tenant-Commander H. B. Soule, and to the executive officer, Lieu- 
tenant L. B. Porterfield. 
To Professor C. A. Kofoid is due much of the eredit for initiating 
the entire project here discussed, as well as for giving to the authors 
the benefit of his wide experience in marine exploration throughout 
the course of the work. 
Through the courtesy of the University of California we have 
much of the time occupied quarters in the Zoology Building, in which 
considerable portions of our laboratory work have been carried on. 
Acknowledgment must be made to Professor R. 8S. Holway for 
valuable information and suggestions regarding the hydrography and 
physical geography of this region. To Mr. H. D. McGlashan, district 
engineer of the United States Geological Survey, we are indebted for 
information regarding the flow of the two great rivers which discharge 
