^ 



PREFATORY. 



Upon the publication of the first part of the West American Oaks, Mr. McDonald was 

 impressed with the necessity of further examination and study of the new species and 

 varieties mentioned therein. These had not been known to Dr. Kellogg : the systematic 

 plan of collection, investigation and representation, which was his life work, was broken 

 by declining health and by adverse circumstances. 



After a few copies of the work had been sent out, the further distribution was sus- 

 pended until the new species should be illustrated ; and Mr. McDonald suggested that 

 special examination should be made to secure satisfactory specimens. When the matter 

 had been fully discussed Professor Greene volunteered to give his summer vacation to the 

 field work in the Sierra Nevada, and in the Rocky Mountains of Colorada and Montana. 

 Mr. McDonald generously bore all the expenses of this trip, and the result has been the 

 verification of former species and the acquisition of new ones. Professor Greene has since 

 employed his hours outside of University duties in the description of all these species, and 

 in the direction of the drawing by Mr. George Hansen. 



It was at first proposed to omit all of the first part of this Volume after page 44, but 

 finally decided to add the second part thereto, in order to make the history and biblio- 

 graphy of the work complete. 



GEORGE DAVIDSON. 



San Francisco, California, 



April 26th, 1890. 



