PREFATORY NOTE. 



This memoir is the first of a series designed to illustrate 

 the biological investigations and explorations undertaken 

 by the Hopkins Biological Laboratory, a branch of the 

 Leland Stanford Jr. University, under the especial pat- 

 ronage of Timothy Hopkins, Esq., of Menlo Park, Cal- 

 ifornia. The present paper is published with the co- 

 operation of the California Academy of Sciences. It 

 appears simultaneously in its present form and as part of 

 the proceedings of the Academy. 



Charles H. Gilbert, 

 Oliver P. Jenkins, 



Editors. 

 Date of publication, September 7, 1895. 



