LEPIDOPTERA. 203 



lies 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 

 oi 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. 65), 

 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 Generalized Frenatce (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 2 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 Taxono?ny- 

 This essay forms a part of the Wilder Quarter-Century Book, published by 

 the Comstock Publishing Company, Ithaca, N. Y. 



