198 University of California Publications in Zoology [ Vo1 - 



INTRODUCTION 



The first field work formally undertaken by the Museum of 

 Vertebrate Zoology, after its inauguration in March. 1908. was 

 centered in the San Jacinto Mountains of southern California. 

 The contiguous regions on both the desert and Pacific sides were 

 included in the explorations. This program was settled upon in 

 part because this particular area remained at that time the least 

 known part of southern California as regards its vertebrate 

 fauna, and in pari because there were likely to be presented here 

 in accentuated degree peculiar distributional features dependent 

 upon the great altitude of the mountain itself and the close juxta- 

 position on cither hand of the sharply contrasted faunas of the 

 desert and coast regions. 



Furthermore, (here were already available the collections and 

 informal ion resulting from the senior author's work in the San 

 Bernardino Mountains, since published (Grinnell, 1908). This 

 afforded a basis for a systematic plan of action looking towards 

 verification of certain previously entertained hypotheses. 



During the five years' interim, from the date of concluding 

 the San Jacinto field work until the final compilation of the 

 present report, much pertinent data has been secured from 

 studies of related areas. These additional sources of information 

 have enabled us to interpret the distributional problems con- 

 cerned with the San Jacinto area as we could not have done 

 otherwise. All of this contributory faunistic work, as well as 

 the main undertaking, has been made possible through the con- 

 tinued financial support provided by Miss Annie M. Alexander, 

 who has thus shown in an effective way her belief in the ultimate 

 value of efforts expended in this line of scientific inquiry. 



The San Jacinto Mountains form a sharply segregated sec- 

 tion in the series of high ranges which cut off the fertile coast 

 valleys of southern California from the arid deserts of the 

 interior. The San Bernardino Mountains lie directly to the - 

 northward, with the gap formed by San Gorgonio Pass between. 

 To the southward is the Santa Rosa range, separated but slightly 

 from the main San Jacintos, and farther south are various smaller 

 mountain chains (see profile, plate 7). 



