366 



THE WINGS OF HYMENOPTERA 



towards the base of the wing has so modified the course of that part of vein 

 M4 which is still free that it extends towards the base of the wing. This 

 change is very similar to the change in the course of vein Cu2 in the dipter- 

 ous genus Rhamphomyia (Fig. 385). 



A curious result of this change in the direction of the course of vein M4 

 is that the cell M4 has been closed and pressed back to the center of the wing 



^4 + J 



Fig. 385. — Wing of Rhamphomyia. 



(Fig. 382, M4), and now lies in front of the free portion of vein M4 instead of 

 behind it. A somewhat similar modification of cell Ms is found in the 

 dipterous genus Eulonchus (Fig. 386). 



Let us now consider the courses of the branches of the radius. Here 

 again we can gain help from a study of dipterous wings. Observe in 

 Pantarbes (Fig. 384) the coalescence of the tips of veins R5 and Mi. In the 

 Hymenoptera a similar coalescence of veins R5 and Mi has occurred; but it 

 has proceeded much farther, so that the free portion of vein R5 in Pampkilius 



Fig. 386. — Wing of Eulonchus. 



(Fig. 391, Rr.) is remote from the end of the wing and has the appearance of 

 a cross-vein. 



In the Hymenoptera vein Rr, has been followed in its migration along 

 vein Ml by vein R4, which has now reached a stage in Pamphilius that is 

 quite similar to that reached by vein R.^ in Pantarbes; but like vein R5 it has 

 the appearance of a cross-vein. In the fore wing of the honey-bee (Fig. 



