164 GRAMMAR OF ENTOMOLOGY. 



beetles between the moths and the butterflies ; 

 neither would any one place one of the moths, 

 or butterflies, between the two beetles : thus the 

 most untaught mind acknowledges the existence 

 of a system. 



607. Resemblances, in natural history, are not 

 dependent on the outward and obvious distinc- 

 tions of size and colour, but are to be traced in 

 other characters ; in economy, habit, and struc- 

 ture. Economy comprises the acts of a living 

 being, as described in the First Book of this 

 volume ; structure is described in the Second 

 Book ; and habit is the external form and appear- 

 ance ; in fact, the result of structure. 



608. In arranging, it is necessary to consult 

 all these characters, but principally structure, 

 because, under all circumstances, we gain some 

 knowledge of this ; whereas, habit may be occa- 

 sionally altogether deformed, and economy fre- 

 quently altogether unknown : in structure, primary 

 variations occur in the systems of organs ; secon- 

 dary variations in the details, which comprise a 

 system of organs. 



609. In all animals, the bones, or organs of 

 support, and the covering of the surfac,e of the 

 body, as skin, hair, feathers, or scales, afford the 

 most ready characters by which to distinguish 

 different kinds of animals from each other : now, 

 in insects, we have seen that the organs of support 

 are on th^ surface of the body, and, therefore, 



