PREFACE. 



The science of Entomology, in this country, is to a very con- 

 siderable degree traditional. The series of specimens which are 

 arranged and named have assumed their scientific value entirely 

 from the labors of four or five individuals, who, from peculiarly 

 favorable circumstances, have been enabled to lay a groundwork 

 for scientific investigation by conference or correspondence with 

 European students. 



The present small treatise, prepared at the request of the 

 Smithsonian Institution, is intended, so far as relates to the 

 determination of genera of Coleoptera, to obviate the necessity 

 for this traditional knowledge, and to enable those who have a 

 desire beyond that of the mere collection of specimens to acquire 

 sufficient information to enable them to consult with profit the 

 various works in which are found scattered the descriptions of 

 our species. 



At the same time it is designed to present in as compact a 

 form as possible the most recent results of scientific analysis, as 

 applied to the classification of those genera of Coleoptera which 

 have been found in that portion of America north of Mexico. 

 In presenting these results, I have by no means adhered to the 

 opinions expressed by those who have previously written on the 

 classification of the order of insects which will occupy our atten- 

 tion ; but where it has seemed to me possible to change with 

 advantage the schemes already proposed, I have not hesitated to 

 alter them. 



The work is, therefore, intended for two classes of persons — 

 for those who wish to obtain a knowledge of this branch of 

 science, and for those who have already acquired that knowledge, 

 and who now occupy the position of investigators. 



The first class, or beginners, will here find the elementary 



iii 



