HARD PARTS OF THE GRASSHOPPER. 239 



larly marked with dark-brown pigment spots. It is 

 strengthened by a network of chitinous tubes, the " veins "; 

 of which there are five on each wing, diverging from 

 the proximal end of the wing, and giving rise to smaller 

 veins. These in turn divide into much smaller veinlets, 

 which inosculate with each other and divide the surface 

 of the wing into small irregular polygonal areas or "cells." 



(i.) The vein nearest the anterior or costal margin of the 

 wing is the costal vein. It is undivided, and may be traced 

 for a little more than half the .length of the wing. 



(ii.) The second very much larger vein is the sub-costal. 

 It gives rise to several large branches, the subdivisions of 

 which form the framework of the greater part of the 

 wing. 



(iii.) The third or median is much smaller, and soon 

 divides into two branches of nearly equal size. 



(iv.) The remaining pair, which are known as the sub- 

 median and internal, run close to and nearly parallel with 

 each other near the internal or posterior margin of the 

 wing. 



c. The wmg is divided by the veins into three areas : 

 (i.) The costal area forms the anterior edge of the wing, 



and is bounded posteriorly by the costal vein. 



(ii.) The median area is much the largest, and lies be- 

 tween the sub-costal and sub-median veins. 



(iii.) The internal area is the free margin posterior to 

 the internal vein. 



d. Make a sketch of the wing-cover, showing the above 

 points. 



e. The second pair of wings are about equal to the first 

 in length, and w r hen the animal is at rest are folded up 

 under the latter. On the side from which the wing-cover 

 has been removed seize the dark-colored maririnal vein of 



