568 INVESTIGATION OF INSECTS. 
above, only a sexual character 3 . , Authors also in their 
descriptions in this respect sometimes mislead the young 
student. When Linne calls the thorax of Aphodius er- 
ratlcus smooth (lavis), he would not expect to find it co- 
vered with impressed puncta, and with a longitudinal 
posterior impressed line. Likewise in describing Chlccnius 
vestitus and nigricornis, Fabricius passes without notice 
their punctate surface, so different from that of other 
Harpalidce. Errors of this kind however, it is but fair 
to observe, are chiefly to be attributed to the circum- 
stance that both Linne and Fabricius rarely employed 
a microscope in making descriptions; though no one now 
. attempts this, except where insects are large, without 
such an aid. 
If you ask, How am I to acquire this delicacy of tact 
which is to decide when the terms of a specific character 
are to be rigidly adhered to, and when taken with a cer- 
tain latitude ? I answer, In the same way in which a 
connoisseur attains the faculty of discerning the works 
of different masters in painting ; — by such careful study 
of your author as will make you master of his style. 
Thus you will soon perceive in what cases expressions 
are to be taken literally and strictly, or with some al- 
lowance and abatement. 
There yet remains more distinctly to be adverted to, 
the assistancethat may be derived in the investigation of 
insects fromjftgures. Generally speaking, these should 
never be referred to in the first instance, but be regarded 
as a resource when the ordinary methods leave the sub- 
ject of inquiry doubtful. Those who begin their ento- 
a Vol. III. p. 304. 
