168 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Stanford University, University of Oregon, and University of 

 Washington. 



The most important works used in this study are given in 

 the appended bibhography, though many others, not cited, were 

 consulted. 



The classic writings of Carpenter, Gould, and Cooper on 

 the Recent Mollusa gave the groundwork for the investigation. 

 The pioneer works of Conrad and Gabb on Tertiary fossils 

 gave the basis for comparison of Recent and Tertiary faunas. 

 This was amplified by detailed study of the later literature, 

 especially of Dall on the Recent and Tertiary faunas, and of 

 Arnold on the Tertiary of California. Also the papers of 

 Weaver on the Tertiary faunas of Washington have been in- 

 valuable, in determining the horizons of the Puget Sound 

 region, and comparing them with those of California. 



The writings of Dall, Arnold, Anderson, Hannibal, Dicker- 

 son, B. L. Clark, C. A. Waring, J. M. Nomland, and many 

 others, on Tertiary geographic conditions on the West Coast, 

 have changed many of our old ideas on the subject, and neces- 

 sitated much revision. 



It has been the aim of the writer to bring the information on 

 the subject up to date, and to formulate results of his own 

 studies as well as those of the other workers in the stratigraphy 

 and paleontology of California. 



