OF THE WINGS AND LEGS. 167 



appearance of wings, and have become simple bristles, 

 totally useless in flight. It should, however, be observed, 

 that some authors have expressed doubts as to the identity 

 of these undeveloped and imperfect wings, with the obvi- 

 ously perfect and complete hind wings possessed by beetles, 

 butterflies, bees, &c. Questions of this kind are deeply 

 interesting to the abstruse physiologist, but to the practical 

 entomologist are of little or no value. The main object 

 of a describer is to make himself clearly understood, and 

 of a reader clearly and quickly to understand; and, to 

 both these classes, it is almost a matter of indifference 

 whether the two fully developed wings of gnats and flies 

 are equivalent to the fore or hind wings of the bee. 



The nervures in membranous wings divide the membrane 

 into small compartments, called cells or cellules: these 

 cells are very constant in their form and proportion in the 

 same genus of insects ; consequently their variations dis- 

 tinguish one genus from another. The strong nervure which 

 runs along the upper edge of each wing, either on the 

 extreme edge or just below it, is called the costal nervure 

 or nervura costalis ; and the portion of membrane, if any, 

 above this nervure, is the costal cell, or if divided by mi- 

 nor nervures, the costal cells or cellula costales, m. The 

 incrassated portion of this nervure, g, which is frequently 

 observable at about two-thirds of the distance from the 

 body, towards the apex of the wing, is called the stigma, 

 both in English and Latin descriptions. The cells imme- 

 diately beyond the stigma, towards the extreme point of 

 the wing, are called the marginal cells or cellul<e maryi- 

 nales, h h ; these are generally two or three in number ; 

 and the cells immediately below these, the submarginal 

 cells or cellula submarginales, k k k k. The wings of all 

 insects present a somewhat triangular figure. The upper 

 portion of this triangle is called the costal region or regio 



