vra 
PREFACE. 
America, and other memoirs, by Dr. Geo. H. Horn. But whenever a 
general enumeration of the species in any group is given, without quali- 
fication, it must be understood to embrace all the known North American 
species. In stating the numbers of species, I bavefollowed, for the most 
part, the recently published Check List of Mr. G. R. Crotch, (1874). 
Where two or more closely allied genera or sub-genera are merged in one, 
all the species are, of course, included under the leading generic title. 
A precise adjustment of species formed no part of my plan, and my 
principal object in giving these numbers has been to show the compara- 
tive numerical importance of the several families and their leading or 
typical genera. 
In the definition of genera I have had constant reference to the great 
work of Lacordaire on the genera of Coleoptera* ; and to Dr. J . L. Le- 
Conte’s very accurate and scientific classification ot the Coleoptera of 
North America, prepared for the Smithsonian Institution. (Part 1st, 1 
vol., 8 vo., 1861 ; and Part 2d, 1873.) To these elaborate systematic 
works, and especially the latter, which, for obvious reasons, is most 
readily available to the American student, the present treatise is only 
intended to serve as an introduction or stepping stone; and to them the 
reader is referred for more extensive details, and for the definition of 
the smaller families and genera not included in the present work. 
In the families Chrysomelidae, Erotylidae, Endomychidie and Coccin- 
ellid®, which have not been reached in either of the uncompleted works 
just referred to, 1 have derived valuable aid from the synopsis of these 
families by Mr. G. R. Crotch, recently published in the Proceedings of 
the Academy of Natural Sciences of Philadelphia, and in the Transac- 
tions of the American Entomological Society. 
In treating of the internal structure of insects I have necessarily lim- 
ited myself to the briefest geueral statements. Those who wish to pro- 
secute further this department of the science, will find much interesting 
matter in Dr. A. S. Packard’s well known Guide to the study of In- 
sects. 
It will be seen that some of the families of Coleoptera are much more 
fully treated than others. This has been owing, partly, to the greater 
amount of material at my command, partly to the comparative impor- 
tance of certain families in a practical or economic point of view, and 
partly to the irregularity of the intervals at which the work has been 
prosecuted, which has prevented that uniformity of execution which 
would have been desirable. 
In order to make this little work as useful as possible, I have added 
a glossary of the terms most commonly used in descriptive entomology ; 
and also, a brief catalogue of authors, especially those whose names ap- 
Genera des Coleoptera.. Ten vols. 8 vo., Paris, 1854-1872. The author died before the completion 
of thin work, and the tenth volume has not yet been published. 
