THE GENERAL FEATURES OF WINGS 



o9 



tion between the cubitus and the first anal vein; but in the males of the 

 Locustidas and the Gr\41ida3 the anal furrow crosses vein Cu2. It is evident, 



Fig. 40.- 



-Typical hymcnopterous wing. The median furrow and the 

 anal furrow are indicated by dotted lines. 



therefore, that this furrow is merely a fold in the adult wing, and that its 

 position is variable. 



The median furrow. — This is a longitudinal furrow which is usually 

 between radius and media (Fig. 41, mf). It is well-marked in many of the 

 Heteroptera, where it separates the embolium from the remainder of the 

 corium (Fig. 42) ; and in the Hymenoptera its course is marked by a series 

 of weak spots, the bullae, in certain veins (Fig. 40). 



The nodal fiirroiv. — The nodal furrow is a transverse suture beginning at 

 a point in the costal margin of the wing corresponding to the nodus of the 

 Odonata and extending towards the inner margin of the wing. It crosses a 

 varying number of veins in different orders of insects. It is well-shown in 



%i 'fe 



S{ » 



% 



'q:9' 



'■^V^S^f 





vA<;*«'' 





Fig. 41. 



-Fore wing of a bug, Hormostes reflex ul us; ni f, median furrow; 

 a f, anal furrow (After C. & X.). 



the fore wing of the flower-bug (Fig. 42) ; and in the fore wing of a Cicada 



(Fig. 43, n f). The nodal furrow is termed the costal hinge by some writers. 



The axillary furrow. — The axillary furrow is a suture-like line extending 



from the base of the wing to the inner margin ; it ends at the axillary excision 



