590 TAXONOMY. 



Typh&us, and many exotic species. A striking instance of the influ- 

 ence which good or bad nutriment has upon the development of the 

 larva is exhibited to us in the practice of the bees rearing queens from 

 the larvae of the neuters. 



These facts show that the establishment of a true species is not so 

 easy an affair, and that it requires very comprehensive tact. Good 

 specific characters however may be derived from the general form, the 

 form of individual parts, especially of the head and thorax, the sculp- 

 ture or markings of the external integument ; after which the size and 

 the relative proportions of different parts ; and lastly, also even colour. 



The specific character, or sum of ^ill the essential characters that 

 define the species, serves for the distinction of a species. 



325. 



II. IDEA OF A GENUS. 



Above the species stands the group, which has been called the 

 genus. A genus is composed of several species, which agree in certain 

 qualities of essential parts or organs ; its idea consequently comprises 

 that of conformity. 



This, in itself correct definition, admits however of a variety of inter- 

 pretations, according to the object aimed at in the foundation of the 

 system. Artificial classification divides where it observes divarications 

 and differences in the organs adopted as the basis of the subdivision ; 

 whereas the natural system regards the harmony of all the organs, and 

 only forms divisions where divarications of decided importance are 

 observed in those organs. An example will speedily illustrate this. 

 Fabricius, whose classification, founded upon the oral organs, is evi- 

 dently artificial, divided the Chrysomelina, according to the structure 

 of the parts of their mouths, into several genera, and referred to these 

 genera all those leaping beetles which Geoffrey and Illiger united in 

 the one genus Haltica, according as the parts of the mouth, or even 

 merely the external form, appeared to agree with the characters of this 

 or that family ; the most prominent character, that of leaping, he left 

 quite unnoticed, keeping merely the principles of his system in view. 

 Latterly, however, and even indeed formerly, as soon as it was wished 

 to form natural genera, the greatest attention has been paid, and justly, 

 to this power of leaping, and it has consequently been considered as 

 the chief characters of these creatures, and indeed they appear to be 

 particularly distinguished by it. 



