X INTRODUCTION 



the difficult genus Thamnophis references are given to Ruth- 

 ven's excellent review. Common names for reptiles and am- 

 phibians are in great confusion, and are often of generic rather 

 than of specific application. No attempt is made to recognize 

 any except those which are in well-established usage. The 

 host which have been recently coined by various writers are 

 frequently inapt and almost surely unlikely to survive. It is 

 entirely possible that some vernacular names really often 

 used have escaped our notice, since many are in restricted 

 local use. The type localities are as nearly exact as it is pos- 

 sible to determine. This cannot be said regarding the ranges. 

 Many are obviously faulty, but a sincere attempt has been 

 made to collect records of authentic captures; however, with 

 a literature so extensive and so scattered, records have almost 

 surely been overlooked. In many cases, our knowledge does 

 not warrant drawing hard and fast lines delimiting a form's 

 occurrence, and we often state ranges in purposely general 

 terms. There still is opportunity for valuable field work to 

 determine the precise distribution of many of our most com- 

 mon species. An example is the recent discovery that Vir- 

 ginia valeriae is far from rare in parts of New Jersey. 



Our hearty thanks are due to many for information and 

 advice, especially to Samuel Henshaw, John Van Denburgh, 

 and Alexander G. Ruthven. 



G. K. Noble has assisted considerably in verifying refer- 

 ences and searching literature, and for this assistance he has 

 our grateful remembrance. 



T. B. 



