PREFACE. 
As this essay never before appeared under its present 
title, it seems necessary to explain why it is called a 
second edition. 
In the year 1832 I published an essay under the 
title of c Sphinx Vespiformis/ the object of which was 
to set forth the views now more fully explained. 
The essay in question contained three chapters;— 
the first ‘ On the Primary Division of Nature; ’ the 
second ‘On the Classes of Insecta;’ and the third 
( On the Sub-classes of Lepidoptera.’ 
The third chapter, treating solely of Lepidoptera, 
is entirely omitted in the present edition, and this for 
two reasons;— first, the subject seemed complete 
without that chapter; and secondly , my knowledge of 
Lepidoptera is not sufficiently extensive to enable me 
to elucidate my views by an analysis of that beautiful 
class. The insect whose situation formed a principal 
subject of the chapter in question, is not mentioned 
in the present edition, consequently its name, as a 
title, could not, with propriety, be retained. 
