THE WINGS OF HYMEN OPT ERA 



367 



387) veins R4 and R5 still retain the appearance of branches of a forked vein. 



In Paniphilius vein Ri is cur\'ed away from the costal margin of the wing 



to make room for a stigma (Fig. 391 and Fig. 382, st), and vein R3 ends in 



Fig. 387. — Wings of a honey-bee (From C. & N.). 



the costal margin a short distance before the apex of the wing. Vein R2 

 has been lost in this genus but as it is well-preserved in the closely allied 

 genus Macroxyela (Fig. 392) it is represented in the figure of the typical 

 h^Tiienopterous wing (Fig. 3S2). 



While the tips of the branches of the radial sector have migrated away 



from the apex of the wing, 

 the bases of these branches 

 coalesce in the opposite 

 direction; from these two 

 causes results the transverse 

 bracing of the radial area of 

 the wing, which is a very 

 characteristic feature of the 

 venation of the wings of this 

 order. 



The details of these 

 changes will be made clear 

 by an examination of Figures 

 388a and 388b. The former 

 represents the primitive 



Fig. 388. — Diagrams of the radius: a, typical; 

 b, hymenopterous (After C. & N.). 



mode of branching of the radius; the latter, the radial area of the typical 

 hymenopterous wing. As the radial cross-vein is usually present in the 

 H>Tnenoptera, it is represented in these figures. In the hvTuenopterous 

 type, veins R2+3 and R4+5 of the primitive t>T3e coalesce so far that the 



