HOW TO KNOW THE BUTTERFLIES 



It is only in a very few Lepidoptera that there 

 is any indication of the existence of vein M 4 . In 

 nearly all moths and in all butterflies media ap- 

 pears to be only three-branched ; and it is custom- 

 ary to regard the vein labeled M 4 4- Cu, in the 

 above figure as merely cubitus-one. For the sake 

 of simplicity this course is followed in this work. 



The most striking modification of the primi- 

 tive type that has taken place in the wings of 

 butterflies is the loss of the main stem of media 

 and the joining of the branches of media to the 

 veins on either side. Thus vein M, appears to be 

 a branch of radius ; vein M 3 , of cubitus ; and 

 vein M 2 is sometimes joined to radius and some- 

 times to cubitus. That this change has taken 

 place is easily seen by comparing the venation of 

 StJienopis (Fig. 6) with that of the various but- 

 terflies figured here. 



Not only has the main stem of media been lost, 

 but in nearly all wings of butterflies one or two 

 of the three anal veins have disappeared. A care- 

 ful study has shown that in the reduction of anal 

 veins in the Lepidoptera the first anal vein is the 

 first to disappear, and the third anal vein is the 

 next to go. 



The number of the branches of a branched 

 vein is often reduced by the growing together, or 



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