332 



LEPIDOPTERA 



structures is sometimes ornamental. As a rule, however, the 

 " l)rands " of male Lepidoptera detract from their beauty to 

 our eyes. 



Fio. 173. A, section of part of wing showing the complex androconia of Thanaos (ages, 

 a Skipper butterfly. The turning over of the costal margin of the wing is in this 

 case part of the arrangement. <<. Upper covering-scales attached to the costal 

 portion of the under surface of the wing ; b, edge of costal margin of the wing ; 

 c, costal nervure with its scales ; d, field of the wing next the costal nervure, bearing 

 stunted scales : e, the androconia proper, or male scales ; f, posterior covering 

 scales ; (/, lumen of the costal nervure : B, a portion of the costal area flattened 

 out and seen from above ; lettering as before : C, section of androconium on the 

 second nervure of Argynnis paphia. (After Aurivillius.) 



Resuming our consideration of the development of the wings, 

 we may remark that the history of the changes during the 

 pupal state is still imperfect. By the changes of relative size 

 of the thoracic segments the hind wing is brought to lie under 

 the anterior one (i.e. between it and the body), so that in the 

 newly formed pupa the arrangement is that shown in Fig. 1*74. 

 The wings are two sacs filled with material surrounding peri- 

 tracheal spaces in which run tracheae. The subsequent history 

 of the tracheae is very obscure, and contrary opinions have been 

 expressed as to their growth and disappearance. We have 

 alluded to the fact that in some nervures tracheae are present, 

 while in others they are absent ; so that it is quite possible that 



