2 BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



About 1,200 specimens were examined. The number of specimens 

 in collections, however, is no criterion of the relative abundance of 

 these snakes, as the large size of the individuals has evidently made 

 the accumulation and preservation of large series of specimens seem 

 impractical. The lack of definite locality records has rendered useless 

 in the study of geographic variation a small percentage of the speci- 

 mens examined, and in several cases the localities recorded are obvi- 

 ously erroneous. The importance of detailed locality data, accom- 

 panied by physiographic and ecological records, cannot be stressed 

 too strongly. Such data will immeasurably increase the value of 

 specimens in modern taxonomic work. In several groups the mate- 

 rial available is admittedly inadequate, and a conclusive study of 

 variation in these forms must await the collection of larger series of 

 specimens. 



Most of the extant types in America are in the collection of the 

 United States National Museum, and all these were examined. 

 Detailed descriptions of the types in the Museum d'Histoire Naturelle 

 de Paris were very kindly sent to me by M. F. Angel. 



I am greatly indebted for assistance to several individuals and 

 institutions. In addition to the collection of specimens in the Museum 

 of Zoology of the University of Michigan, which served as a nucleus 

 for the work, I have had access to the collections of many museums 

 and universities and to the private collections of several individuals. 

 Often single specimens proved of unusual value; some by showing an 

 extreme variation, others by contributing a new locality record. 

 Every additional specimen, even though it possess no unusual features, 

 is an important contribution in swelling the numbers necessary for 

 accurate interpretation of individual, sexual, and geographic variation. 



ACKNOWLEDGMENTS 



I wish to express my appreciation to Dr. Leonhard Stejneger and 

 Dr. Doris M. Cochran, of the United States National Museum; to the 

 late Dr. B. W. Evermann and Joseph K. Slevin, of the California 

 Academy of Sciences; to the late Prof. Joseph Grinnell, of the Museum 

 of Vertebrate Zoology, University of California; to Dr. Thomas 

 Barbour and Arthur Loveridge, of the Museum of Comparative 

 Zoology of Harvard University; to Dr. G. K. Noble, of the American 

 Museum of Natural History; to Prof. J. O. Snyder, of Stanford Uni- 

 versity; to Henry W. Fowler, of the Academy of Natural Sciences 

 of Philadelphia; to M. Graham Netting, of the Carnegie Museum; to 

 Karl P. Schmidt, of the Field Museum of Natural History; to Dr. 

 Howard K. Gloyd, of the Chicago Academy of Sciences; to Prof. W. 

 B. Wilson and Dr. Wesley Clanton, of Ottawa (Kans.) University; 

 to Dr. A. I. Ortenburger, of the University of Oklahoma Museum of 

 Zoology; to the late Prof. J. E. Guthrie, of Iowa State College of 



