CHAPTER III 
THE CLASSIFICATION OF MOTHS 
“The filmy shapes that haunt the dusk.” 
Tennyson, In Memoriam , xciii. 
The insects of to-day, like the animals of all other classes 
found upon the globe, represent lines of descent from an ancestry, 
which runs back into the remote geologic past. The attempt to 
trace the lines of descent in any order by studying the resem¬ 
blance between genera and species as they exist to-day, while 
throwing considerable light upon the subject, can never yield 
wholly satisfactory results in the absence of testimony derived 
from the field of paleontological inquiry. The study of fossil insect 
life is as necessary to elucidate the story of the development of 
the insect world, as the study of fossil vertebrates is necessary in 
order to understand the manner in which existing mammals have 
been derived from preexisting forms. At best descent can only 
be positively asserted within the lines of those groups, to which 
naturalists have given the name of families. Within these it is 
possible to declare of this or that genus that it has been possibly, 
or even probably, derived from the same stock as another. 
Reference to a common ancestral form may safely be predicated 
of very few families, so far as such assertion of a common 
parentage rests upon evidences found in the living structures of 
to-day. 
All attempts to classify the lepidoptera in such a manner 
as to show the derivation of one of the existing families from 
another, and to maintain a lineal sequence in the order given, 
must necessarily prove wholly disappointing. The fact is, that 
the various families represent divergences from the parent stem, 
which may be likened to the divergence of the branches from the 
trunk of a tree. Any system of classification, which leaves this 
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