330 



LEPIDOPTERA 



trachea, and also a " wing-rib " and blood-cells. Pie remarks that 

 even in uervures, perfectly formed as to their chitinous parts, 

 either wing-rib or trachea or both may be absent. 1 Schiiffer' J 

 was unable to find any tracheae in the completed wings he 

 examined, and he states that the 

 matrix of the tracheae and even 

 their inner linings disappear. The 

 wing-ribs were, however, found by 

 him to be present (Fig. 170, A 

 and B). 



The scales that form so con- 

 spicuous a feature in Lepidoptera 

 exist in surprising profusion, and 



FIG. 170. Structure of wing of imago. A, 

 Transverse section of basal portion of wing 

 [of Vanessa ?] containing a nervure ; c, 

 cuticle ; fr, wing-rib ; y, wall of nervure 

 ("Grundmembran ") ; /i, hypodermis ; p, 

 connectingcolumns : r, lumen of nervure ; B, 

 section of a rib ; b, one of the chitinous pro- 

 jections ; sir, central rod. (After Schaffer.) 



FIG. 171. Scales of male Lepidoptera. 

 A, Scale from upper surface of 

 Everes comyntas ; B, from upper 

 surface of 1'ieris rapae ; C, from 

 inner side of fold of inner margin 

 of hind wing of Laertias philenor ; 

 D, one of the cover-scales from the 

 costal androconium of Eradamvs 

 protects ; E, F, G, scales from andro- 

 conium of Tlwrybespylades. (After 

 Scudder). 



are of the most varied forms. They may be briefly described 

 as delicate, chitinous bags ; in the completed state these bags 

 are flattened, so as to bring the sides quite, or very nearly, 

 together. Their colour is due to contained pigments, or to stria- 

 tion of the exposed surface of the scale ; the latter condition 



1 Zeitschr. wiss. Zool. liii. 1892, p. 623. - Zool. Jahrl. Anat. iii. 1889, p. 646. 



