2 BULLETIN 18 7, UNITED STATES NATIONAL MUSEUM 



Aside from the two collections mentioned, we have seen or otherwise 

 checked all Mexican snakes (excluding those from Baja California) 

 in the Museum of Vertebrate Zoology, California Academy of Sciences, 

 Museum of Comparative Zoology, Chicago Academy of Sciences, Mu- 

 seum of Zoology of the University of Michigan, University of Utah 

 Museum, Carnegie Museum, Brigham Young University, Chicago 

 Natural History Museum, the personal collection of L. M. Klauber, 

 San Diego Society of Natural History, and Stanford University Mu- 

 seum. A few specimens have been examined in the collections of the 

 American Museum of Natural History and the Academy of Natural 

 Sciences of Philadelphia. While we have not incorporated herein all 

 data from these collections, since some are undergoing study by other 

 students, much distributional data have been gleaned from them and 

 used to augment those otherwise available. Thus the ranges and lo- 

 calities cited for many species are based upon unpublished records ; all 

 records, however, are based upon specimens examined by us or by other 

 herpetologists, or upon literature records we consider reliable. 



Though our survey of the literature has extended over several years, 

 we may well have overlooked published accounts that would add to 

 our statement of ranges or synonymies. For the benefit of possible 

 future editions we shall appreciate advice of such omissions. 



METHODS AND DEFINITIONS 



Our object has been to list only species known with certainty from 

 any part and possession of Mexico, yet a certain few have been added in 

 spite of the lack of definite records ; these exceptions, however, are so 

 certainly to be found in Mexico that we have had no hesitancy in con- 

 sidering them a part of the Mexican fauna. They are marked with an 

 asterisk preceding the name. Many others are known from nearby 

 localities but for various reasons have been omitted. We have fol- 

 lowed no particular rule in deciding which species we believe almost 

 certainly occur in Mexico and which may not. 



Regarding the use of parentheses for authors' names, despite the 

 gaining popularity of another interpretation, we follow the Inter- 

 national Rules of Zoological Nomenclature, which are clear on this 

 point: "When a species is transferred to another than the original 

 genus or the specific name is combined with any other generic name 

 than that with which it was originally published, the name of the 

 author of the specific name is retained in the notation but placed in 

 parentlieses" (Article 23). Obviously the rule implies that paren- 

 theses are to be used only to indicate the changes prescribed, not in- 

 discriminately to indicate any change of combination. This procedure 

 is not only very clearly indicated but in addition is of very useful, 

 practical application. Use of parentheses to indicate changes other 



