EASTERN UNITED STATES. 



29 



FIG. 6 



and on each side a small, scaly piece covering the base 

 of the fore wings, and known as the shoulder-tuft, lap- 

 pet, or pterygoid. The second and third thoracic joints 

 bear each a pair of wings. These are composed of mem- 

 branes supported by a 

 framework of slender, 

 tapering tubes between 

 the membranes. The 

 fore wings are the largest, 

 triangular in general 

 outline, \vhile the hind 

 wings are more or less 

 rounded or square. The 

 veins or framework are 

 nominally five principal 

 veins, the costal, sub- 

 costal, median, sub- 

 median, and internal. 

 The first two are close 

 together near the front 

 edge of the wing, and Fore and hind wing of a butterfly : ^ fore 



form the COSta (see Fig. wing; a, costal vein; b, subcostal vein; 61, 

 d\ rrn i 6 2, 6 3, 6 4, 6 5, five subcostal veinlets ; c, in- 



b). 1 he median passes dependent vein . rf) median vein . d ,, d 2) d 3> 



through the middle from d 4 > four median veinlets ; e, submedian vein ; 

 , , i /, internal vein ; b and d are situated in the 



the base to near the discal cen . ffl> g ^ g3t t he upper, middle, 

 outer third, where it and lower discal veinlets ; n.wnd wing (the 



. . ,. , lettering the same). 



usually joins the sub- 

 costal by a cross-vein ; and from this and the cross-vein 

 are given off several branches, the subcostal also being 

 branched on its upper side, more in the fore wings than 

 in the hind. The area between the subcostal and median 

 veins is known as the discal cell, or the cell, the branches 

 3* 



