562 INVESTIGATION OF INSECTS. 
authors, particularly Fabricius and Latreille, who have 
subdivided the genera of Linne ; and you will see which 
of your groups agree with theirs, detect your own errors, 
and often theirs, and be enabled to label each of your 
genera and higher groups, if already known, with its 
modern appellation. You are now qualified also to 
enter scientifically into the study of the characters that 
distinguish groups, and may proceed, wherever oppor- 
tunity is afforded, to examine the tropin, which may 
often be displayed sufficiently by the means recommended 
in my last letter a . In this way you may learn also to 
know your groups as well by character as by habit, and 
be qualified to trace the gradual progress of nature from 
form to form ; and may look upon yourself as duly pre- 
pared to put the last hand to your labours, and proceed 
to the examination of species. 
It will have occurred to you, in making out your genera 
or lowest groups, that some consist of a vastly greater 
number of species than others. It seems advisable 
therefore, when you apply yourself seriously to ascertain 
what described ones your cabinet contains, to begin with 
those genera which appear to be poor in them ; for here 
your labour will be comparatively light, from the small 
number you will have to examine ; and you will become 
practised in the employment before you are called upon 
to attack those that overflow. Had Fabricius and 
other describers of species taken the trouble to sub- 
divide the larger groups, as might easily have been done, 
into more genera and subgenera, the student would have 
been spared a most discouraging labour. To be obliged 
:i Sec above, p. 54(i. 
