138 ON STRUCTURE 



Like the anterior pair they have three longitudinal 

 nervures; the anterior (7), which runs close and 

 parallel to the anterior nerveless margin, and often 

 touches it at about half the length of the wing ; 

 the median (8) and posterior (9) run in diverging 

 lines from the base towards the exterior margin 

 of the wing, the anterior and median nervures 

 being almost always joined by a cross nervure, 

 and the median usually united to the posterior 

 by a cross or curved nervure. The actual base 

 of the anterior wing is covered by a little convex 

 somewhat shell-like cap, called the tegula (T). The 

 abdomen is composed of a series of segments in 

 linear arrangement (c 1 c 2 , etc.). These call for no 

 special remark, beyond what has been said in the 

 chapter on males and females, but those who wish 

 to investigate the very interesting questions con- 

 nected with the terminal segments of these 

 creatures should consult some more technical 

 work. 1 The arrangements of the mouth parts 

 and of the apical segments of the Hymenoptera 

 afford perhaps the most important structural 



1 cf. Transactions of the Entomological Society of London., 

 1884, p. 251 et seq. : Hymenoptera Aculeate of the British 

 Islands, etc. 



