^\i PREFACE. 



Part II. Avill embrace tlic anatomy ami physiology of each genus, illustrated 

 with drawings of the dillcrent organs. 



It would have been better, perhaps, to have given the special anatomy of the 

 animal at the same time with the description of its external characters; but as 

 the work is published by subscription, the jilan adopted was thought most 

 advisable, as either part may be had separately. 



For the arrangement of the order Chclonia, I have followed that of Dlmeril 

 and BiBROx, and have adopted the genera that they have cither received or 

 established in their Avork, as far as our reptiles are concerned, with one or two 

 exceptions, which will be found in the body of the work. 



For the order Sauria I have also chosen the classification of Dlmeril and 

 BiBRON, in preference to that of any other naturalists, and have consequently 

 adopted it as far as it applies to the Saurian animals of the United States, with a 

 few exceptions, and the addition of one new genus, Crotophytus, for a western 

 Lizard, Avhich could not be referred to any of theirs. 



For the order Ophidia, I have preferred the classification of Cuvier, though I 

 have been obliged to deviate from it in some particulars, either adding such 

 genera as seemed to me necessary, from other naturalists, as Wagler, Boie, 

 KuHL, ^Scc, or establishing new ones. 



For the order Batrachia, and class Ecaudata, I have followed generally the 

 classification of Dumeril and Bibrox, and have received most of their genera as 

 for as they embrace our Reptiles. 



