THE BUTTERFLY. 1 3 



of indicating the veins has been adopted, as it is the most 

 simple. In another method of referring to the venation, and 

 one that has been much in use, vein 12 of the fore wing 

 would be styled the costal nervure, or vein ; veins 11, 10, 9 

 (absent in figure), 8, and 7 would be the subcostal nervules 



1, 2, 3, 4, and 5 ; 6 would become the upper radial, and 5 the 

 lower radial ; 2, 3, and 4 would be the median nervules 1, 2, and 

 3 ; vein 1 would be the submedian nervure, or vein. On the 

 hind wing, vein la would be the internal vein ; 1 the submedian ; 



2, 3, and 4 the median nervules ; 5 the lower and 6 the upper 

 radials ; 7 the subcostal, and 8 the costal nervures. Just near 

 the base of the hind wing will be noted a short recurved vein 

 (p.c.) ; this is the precostal vein, and so named because it comes 

 before the costal. It is always absent in some species. Com- 

 paring the venation of A and B, it will be seen that in A the 

 fore wing has 12 veins 



and the hind wing 8 veins, 



whilst in B there are only 



1 1 veins on the fore wing, 



but the hind wing has one 



vein more than that of 



A. In the Black- veined 



White, vein 9 is absent 



on the fore wing, and on ,, ,, 1( .,, r 



the hind wing there is one 



internal vein. 



Dust-like as they appear 

 to the naked eye, the 

 scales from a butterfly's 

 wing seen under the mi- Arrangement of Scales, 



croscope are found to be (After Holland.) 



exceedingly interesting 



structures and very varied in shape. Dr. Sharp describes them 

 as " delicate chitinous bags." Chitin, it may be mentioned, is 



c 



