8 PREFACE. 



Erpetology that of Brongniart ; and as the systematic classi- 

 fication of Fishes is in need of much improvement, I still 

 follow in this department the system of Linnaeus. 



In Entomology I have adopted the classification of Lin- 

 naeus ; but in Helminthology I have formed out of the numer- 

 ous orders of Blumenbach, Cuvier, Lamarck, and Oken, only 

 five, for the purpose of simplifying, to beginners, the study 

 of this difficult class. 



The Author. 



New York, May, 1849. 



