THE WINGS OF LEPIDOPTERA 



333 



The coalescence of vein Ri and the subcosta was not suspected until the 

 tracheation of pupal wings was studied; it then became evident. Figure 



Fig. 341. — Hind wing of a pupa of Picris rapcc. 



341 represents the tracheation of a hind wing of a pupa of Pier is rapes. In 

 this wing, trachea Ri extends from the radial fork directly towards the costal 

 margin of the wing until it 

 nearly reaches the subcostal 

 trachea ; it then bends out- 

 ward and extends closely 

 parallel with the subcostal 

 trachea. A single vein is 

 formed about these two 

 trachege; this vein appears 

 to be the subcosta, but the 

 evidence presented by the 

 tracheation of the pupal 

 Vv^ing shows that it is vein 

 Sc+Ri. Figure 342 repre- 

 sents the wings of the adult 

 of the closely allied Pontia 

 protodice, in which it can be 

 seen that a single vein, 

 Sc-|-Ri occupies the posi- 

 tion of the two tracheae just 

 described. 



In the adult wings of 



Fig. 342. 



-Wings of Poiitia protodice. 



the greater number of the Frenata there is no indication of the coal- 

 escence of veins Sc and Ri of the hind wings; this is the case in Pontia 



