330 



LEPIDOPTERA 



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

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

 either wing-rib or trachea or both may be absent.^ Schaffer^ 

 was unable to find any tracheae in the completed wings he 

 examined, and he states that the 

 matrix of the tracheae and e^'eu 



their inner linings disappear. The 

 wing-ribs were, however, found liy 

 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 



" g 



Fig. 170. — Structure of wing of imago. A, 

 Transver.se section of hasal portion of win" 

 [of Vanessa ?] containing a nervure ; c, 

 cuticle ; /;•, wing-rib ; g, wall of nervure 

 ("Grunilmembran") ; A, hypoderniis ; jo, 

 connectingcolumns : r, lumen of nervure ; B, 

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

 jections ; str, central rod. (After SchiiHer.) 



Fig. 171. — Scales of ina.\e Lepidojifera. 

 A, Scale from upper surface of 

 Ei-eres comyntas ; B, from upper 

 surface of Pieris rapae : C, from 

 inner side of fold of inner margin 

 of hind wing of Laertias pJiilenor ; 

 D, one of the cover-scales from the 

 costal androconium of Eudaimis 

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

 conium of T/wrybes pylades. (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. u'te. Zool. liii. 1892, p. 623. - Zool. Jahrh. Anat. iii. 1889, p. 646. 



