564- INVESTIGATION OF INSECTS. 
the Dynastidce and many other Petalocerous beetles, the 
principal specific character is derived from the horns or 
tubercles that arm the head and thorax : in Lucanus 
from the mandibulce ; and in Prio?ius from the marginal 
teeth of the thorax. If the insect, then, you want to 
name belongs to any of these genera, having observed 
its peculiar characters in this respect, you may ascertain 
in a very few minutes whether any already described 
exhibit the same. This facility of investigation can be 
better acquired by practice than precept, and cannot be 
attained all at once. The above hints, however, may be 
of some use ; and cannot fail to be so, if you always en- 
deavour to make yourself acquainted by a previous care- 
ful examination with the characters of every new insect 
you acquire, — whether those of form, colour, or sculp- 
ture, — before you attempt to discover its name in Fabri- 
cius or any other author. 
When you have made such proficiency in the study 
as to be familiar with a few species of each section of an 
extensive genus, the labour of investigation will some- 
times be greatly facilitated by attending to that con- 
formity between the proportions, general aspect, and 
figure of a known and an unknown insect, which Natu- 
ralists express by the name of habit, and which, though 
easily perceived by a practised eye, is described with 
such difficulty. Scientific Entomologists in their de- 
scriptions have usually taken care to place near to each 
other, species agreeing in habit. When therefore you 
know the name of one species, and find another of the 
same general habit, you may commonly take it for 
granted that if described at all by your author, it will be 
placed near that already known to you. Thus, suppo- 
