GENERAL ACCOUNT OF BUTTERFLIES 



which this type has been modified in the Lepi- 

 doptera. 



Taking the hypothetical type (Fig. 5) as an 

 illustration, we see that the veins of the wings 

 can be grouped under two heads : first, longitudi- 

 nal veins, those that normally extend lengthwise 

 of the wing ; and second, cross-veins, those that 





3d A 



2d A 



Fig. 5. — Hypothetical venation of the primitive winged insect 



extend transversely from one longitudinal vein to 

 another. 



The names that have been applied to the longi- 

 tudinal veins, beginning with the one nearest the 

 costal margin of the wing, are casta, subcosta, ra- 

 dius, media, cubitus, first anal, second anal, and 

 third anal. In descriptions these veins are often 

 designated, as they are in Figure 5, by the follow- 

 ing abbreviations of these names : C, Sc, R, M, 

 Cu, 1st A, 2d A, and 3d A. 



Beginning with subcosta, the four veins that 



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