LEPIDOPTERA . 
203 
Ties of Lepidoptera, regarding them as those that depart most widely 
from the primitive type. 
From the foregoing it will be seen that a study of the relation to 
each other of the fore and hind wings gives us important hints as to 
the probable courses development has taken in the different families. 
Equally suggestive hints may be derived from a study of the venation 
of the wings. 
By an extended study of fossil forms and the more generalized of 
living forms, the details of which study cannot be given here,* it has 
been determined that in the primitive Lepidoptera vein V of both 
fore and hind wings was well developed, and extended from the base 
of the wing out through the discal cell. We find that in certain 
families of existing moths this vein is still preserved (see p. 221), 
while in others it has been lost. Those families of the Frenatae in 
which it is best and most uniformly preserved are grouped together 
as the Generalised Frenatcs (see the following synopsis), while those 
in which it is lost or nearly so are considered more specialized. 
With the loss of the base of vein V there occurs a connection of 
its branches with veins III and VII, so that in the more specialized 
forms these branches of vein V appear to be branches of those veins 
(Fig. 241). A study of the extent to which this change has gone 
gives much aid in determining the zoological position of the different 
genera and families. In certain families vein V 3 tends to become 
united to vein III; in others it tends to become united to vein VII. 
This too is an important character, of which use is made in the 
following synopsis. 
The number of anal veins is another character the study of which 
throws much light on the relative position of the different forms. It 
has been determined that the ancient Lepidoptera had at least three 
anal veins in both fore and hind wings. This number has been pre¬ 
served in one or both pairs of wings of the more generalized of living 
moths, but has been reduced to two or even to one in the more 
specialized families. 
Enough has been said, without going into further details here, to 
show that the way to determine the relationships of organized beings 
is to determine the primitive form of their organs and the changes 
that have been brought about in these organs by the action of natural 
* The data upon which these conclusions are based are given at greater 
length in an essay, by the senior author, entitled Evolution and Taxonomy. 
This essay forms a part of the Wilder Quarter-Century Book, published by 
the Comstock Publishing Company, Ithaca, N. Y. 
