GENERAL ACCOUNT OF BUTTERFLIES 



that of the hypothetical type. The more impor- 

 tant modifications are the following : 



The costa forms the costal border of the wing, 

 and does not appear as a distinct vein. This is 

 the case with nearly all insects ; but in many pu- 

 pae the costa is distinct, and it is only in the later 



h-c.o- 



Fig. 6. — Venation of the wings of Sthenopis. 



stages of the development of the wings that it 

 coincides with the costal margin. 



In the hind wings, veins M 4 and Cu t unite for 

 a short distance, and then separate ; in the fore 

 winar these veins unite and remain united through- 

 out the remainder of their length (Fig. 6, M 4 -f- 



Cu,). 



ii 



