LEPIDOPTERA 



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

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

 either wing-rib or trachea or both may be absent.^ Schiiffer"-'' 

 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 f] containing a nervure ; c, 

 cuticle ; f'r, wing-rib ; ff, wall of nervure 

 (" Grundmenibran ") ; A, liyijoderniis ; p, 

 connectingcolunins : r, lumen of nervure ; B, 

 section of a rib ; />, one of the ehitinous pro- 

 jections ; st); central roil. (After SchiiH'er.) 



Fig. 171. — Scales of male Lepidojitem. 

 A, Scale from upper surface of 

 Everes comyntas ; B, from upper 

 surface of Pieris rajoae. ; C, from 

 inner side of fold of inner margin 

 of hind wing o'i Laertias phllcnor ; 

 D, one of the cover-scales from the 

 costal androconium of Eiidamns 

 protcus ; E, F, G, scales from andr<i- 

 conium of T/iori/bes/'i/lcdcs. (After 

 Scudder). 



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

 as delicate, ehitinous 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 

 ^ Zcitschr. wiss. ZouJ. liii. 1892, p. 62-3. - Zool. Jahrh. Anat. iii. 1889, p. 646. 



