6o4 



THE STUDY OF INSECTS. 



spect the homologous veins in the Lepidoptera and Diptera. In the 

 Hymenoptera the tips of the branches of vein III coalesce with 

 other vQins ; and when this coalescence has proceeded for a con- 

 siderable distance towards the base of the wing, the branches may 

 appear like cross-vems, instead of branches of a longitudinal vein. 

 This result is very similar to what takes place in the more specialized 

 Diptera. In Pamphiliis (Fig. 733) vein III2 is wanting; but this vein 

 is present in Mac7'ox-yela (mac-rox-y-e'la) (Fig. 735). In both of 

 these genera there is a cross-vein between veins II Ii and IIl2-f-5 (Fig. 

 733' <^"^j- -^ similar cross-vein exists in some crane-flies, dividing cell 



^-Ill4+,yj 



XII VIII 



Fig, 733. — Wings of a saw-fly, ramphilius^ with the veins numbered. 



nil into two parts (see Fig. 505). In both of these genera also the 

 tips of veins III4 and III5 coalesce with vein Vi to such an ex- 

 tent that these veins appear to be cross-veins. In the w4ng of the 

 Honey-bee (Fig. 730) these veins are more obviously longitudinal 

 veins. 



Vein V is very similar to the homologous vein in the Diptera. It 

 arises from a cross-vein extending from vein III to vein VII. In 

 Pa7nphilius it arises from near the costal end of this cross-vein; but 

 in Apis (Fig. 730) its origin is near the middle of the cross- vein. In 

 the Hymenoptera, however, the cross- vein III-VII is much farther 

 from the base of the wing than it is in the Diptera. In the more 



