EASTERN UNITED STATES. 



29 



and on each «ide 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 



Fig. 6 



fore wings are the largest, 

 triangular 



in general 

 outline, while 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 

 form the costa (see Fig. 

 6). The median passes 

 through the middle from 

 the base to near the 

 outer third, where it 

 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 



Fore and hind wing of a butterfly: 1, fore 

 wing ; a, costal vein ; b, subcostal vein ; 6 1, 

 6 2, b 3, 6 4, b 5, five subcostal veinlets ; c, in- 

 dependent vein ; d, median vein ; d 1, cl 2, d 3, 

 d 4, four median veinlets ; e, submedian vein ; 

 /, internal vein; 6 and d are situated in the 

 discal cell; gl, g 2, gZ, the upper, middle, 

 and lower discal veinlets ; 1 1, hind wing (the 

 lettering the same). 



