[ 484 J 64 



whole sentence in English. It is also an important consideration that 

 in learning the elements of any science or art, an indispensable part of 

 such education is to acquire a knowledge of the more common technical 

 terms which properly belong to it, and which constitute its peculiar 

 phraseology, and which the student will continually meet with in all 

 writings upon the subject. In a work intended, like the present, for the 

 common student, all unnecessary use of such words should, of course, 

 be avoided, and whenever we have found it necessary to use them, we 

 have taken care, as a general rule, to exx)lain theii' meaning, either 

 directly or by the nature of the context. 



The student must not expect that any science can be so simplified as 

 to remove all difficulties ; and especially true is this of so extensive and 

 complex a science as entomology. Nor is it desirable that this should be 

 done. One of the principal advantages to be expected from the study 

 of this science is the admirable mental discipline which it affords. The 

 forms- with which it has to deal are so numerous and diversified, and 

 often, at the same time, so closely allied, that their- classification con- 

 stantly demands a minute and carefid examination, and a discrimina- 

 tive analysis, which, regarded purely as an exercise of the mind, are 

 scarcely inferior to those required by the abstract mathematics, whilst 

 they possess the additional interest which naturally attaches to the 

 study of li\ing beings. 



CLASSIFICATION AND NOMENCLATURE. 



(Classification in natural history, has two objects in view — first, to 

 show the relationship which exists between organized beings, by put- 

 tiug til em in groups in accordance with the similarity of their charac- 

 ters ; and secondly, to facilitate the study of them by enabling the stu- 

 dent to comprehend a great number of different but allied forms under 

 a comparatiN ely small number of general heads, and thus to affVuxl an 

 important aid to the memory. 



By nomenchiture is meant the giving to these groups and the species 

 which compose them distinctive names. This is necessary to enable us 

 either to receive or to communicate knowledge ; and without it natural 

 history could not be raised to the dignity of a science. 



In a department so extensive as that of insects, a very great number 

 of names, not only of species, but of the groups in which these are 

 (joraprehended, nnist be necessarily introduced. It is therefore import- 

 ant that the science shall not be encumbered by the creation of unneces- 

 sary genera, or such as are founded upon slight and unimportant char- 

 acters. It is, indeed, often difficult to determine precisely what charac- 

 ters or combination of characters necessitate or justify the formation 

 of a new genus, or the subdivision of an old one. N'o definition of the 

 term genus which is universally applicable, ever has been, or perhaps 



