22 INSECTS iff GENERAL. 



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

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

 such education is to acquire a knowledge of the more common techni- 

 cal terms which pro])erly belong to it, and which constitute its peculijir 

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

 writings ui)ou 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 explain their meaning, 

 eitiier directly or by tlie nature of the context. 



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

 to remo\e all ditidcjulties ; and especially true is this of so extensive and 

 com[)lex a science as entomology. Nor is it desirable that this should 

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

 stu<ly of this science is the adndrable mental discipline which it atibrds. 

 The forms with which it has to deal are so numerous and di\ ersified, 

 and often, at the same time, so closely allied, that their classili cation 

 constantly demands a minute and careful examination, and a discrimi- 

 na!i\'c analysis, which, regarde<l purely as an exercise of the mind, nre 

 scarcely inferior to those required by the abstract mathematics, whilst 

 they possess the additional interest which naturally attaches to the 

 study of liN'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- 

 ting them 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 com])rehend a great number of different but allied forms under 

 a comjjaratively sinall number of general heads, and thus to afford an 

 imjiortant aid to the mem»ry. 



I>y nomenclature is meant the giving to these groups and the species 

 which com})ose 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 groui)S in which these are 

 com})rehended, must 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 ditficult 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. No definition of the 

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



