276 



THE WINGS OF MEMBRACIDM 



photographs, and as, in the membracid wing, there is a sharp bend at the 

 point at'which the tracheae enter the body, it is difficult to secure a mount 

 in which the base and tip of the wing can be brought into focus at the same 

 time. 



It should be noted that in the membracid wing, as in the other cases 

 where a transverse basal trachea has not been developed, the medial trachea 

 is a member of the costo-radial group. 



A comparison of Figures 276 and 277 with the diagram of the hypotheti- 

 cal primitive type (Fig. 278) is of interest in this connection. 



■^^' Sc, 



Fig. 278. — The hypothetical primitive type of the tracheation of the wings. 



A general view of the wings. — Figure 279 represents the venation of the 

 fore wing of Thelia himaculata and will serve to illustrate the type of the 

 wing-venation of members of this family. A comparison of this figure with 

 Figure 276, which represents the tracheation of the wing of a nymph, will 

 indicate the reasons for the conclusions regarding the homologies of the 

 wing-veins. As the cross-veins are not preceded by tracheae in the Mem- 

 bracidas, the cross-veins shown in Figure 279 are not represented in 

 Figure 276. 



Fig. 279. — The venation of a fore wing of Thelia bimacidata (After Funkhouser). 



