PREFACE 



the plates, these photographs are from living reptiles, and 

 they, therefore, set forth something of the natural attitudes 

 of the various species as well as many details of coloration 

 and scale characters. The securing of living individuals of 

 so many species, and the photographing of them, has in itself 

 involved a vast amount of labor extending over many years. 

 Some of these photographs have already been published in 

 other papers on our western reptiles ; others appear here 

 for the first time. Two photographs have been contributed 

 by friends, Miss S. R. Atsatt and Mr. W. O. Backus. 



This work is primarily based upon the collections in the 

 California Academy of Sciences, which now number more 

 than 46,000 specimens, but use has also been made of 

 material belonging to Leland Stanford Junior University, 

 the University of California, the United States National 

 Museum, Harvard University, the University of Michigan, 

 and the American Museum of Natural History. For the 

 privilege of using these collections I wish to express my 

 obligation to my friends, Doctors Charles H. Gilbert, 

 John O. Snyder, Joseph Grinnell, Leonhard Stejneger, 

 Thomas Barbour, Alexander G. Ruthven, G. K. Noble, and 

 Mr. K. P. Schmidt. I also am indebted, for help in many 

 ways, to my assistant, Mr. Joseph R. Slevin, who captured 

 most of the living reptiles which have been photographed. 

 My thanks are also extended to other friends too numerous 

 to mention here. 



THE AUTHOR. 

 San Francisco, California. 

 February 1, 1922. 



