UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 18, No. 13, pp. 299-336, plates 12-13, 6 figures in text April 20, 191J 



A QUANTITATIVE ANALYSIS OF THE 



MOLLUSCAN FAUNA OF SAN 



FRANCISCO BAY 



BY 



E. L. PACKARD 



CONTENTS 



PAGE 



Introduction 299 



General distribution of the Mollusca 301 



Physical characters of San Francisco Bay 301 



The molluscan fauna of San Francisco Bay 303 



Economic considerations 308 



Factors governing the distribution of the Mollusca 317 



Relation to depth 318 



Relation to type of bottom 318 



Relation to salinity 322 



Relation to temperature 324 



Relation to the available food supply 327 



Relation to the biotic environment 330 



Summary 331 



Appendix 332 



Literature cited ;.... 333 



Explanation of plates 334 



INTRODUCTION 



Improved methods of procedure already applied in several different 

 regions of the world have revealed many of the actual conditions under 

 which the marine animal lives. Increased knowledge of such matters 

 has been made possible, locally, through the Biological Survey of San 

 Francisco Bay made by the United States Bureau of Fisheries. 



The survey was made by the U. S. S. "Albatross" under the 

 direction of a board consisting of Dr. F. B. Sumner, naturalist. Pro- 

 fessor Charles A. Kofoid, and Commander Gr. H. Burrage, U. S. N., 



