20 
BRITISH BEETLES. 
the groups are wider in extent, but all unite in some 
particular characters by which they may be known 
from other portions of the animal kingdom. It 
must however be admitted that the greater part 
of these relations and differences are to a very 
large extent artificial, and adopted more for the sake 
of convenience than because they are known to be 
scientifically correct ; in the case of the Goleoptera, 
with which we have more particularly to deal, it is 
perfectly impossible to arrive at any satisfactory con- 
clusion as regards their definite arrangement, and the 
confusion is increased a hundredfold by the fact 
that authors have often used the same characters as 
specific in one group and generic in another ; it is, in 
fact, perfectly impossible to define in words what 
constitutes a genus, a species, or even a variety. 
The beginner must in a great degree dismiss size 
and colour from his mind in investigating Beetles 
critically, and rather rely upon structure and sculpture, 
— as the former are bad guides, though good com- 
panions. An examination of the number and shape of 
the joints of all the tarsi, and the structure of the 
antennae and palpi, will usually afford a sufficient clue 
as to the section in which any individual species should 
be placed : further characters are to be sought in the 
relative length of the thorax and elytra, the develop- 
ment of the different limbs, the existence or non- 
existence of wings, and, above all, in the parts of the 
mouth, and the formation of the under-skeleton : the 
latter character is now regarded as one of the most 
valuable, but the formation of the mouth organs is still 
in many cases a very reliable character ; these organs 
are extremely variable, and in order to be properly 
