1919] Braun: Wing Structure of Lepidopter a 357 



Adela bella (Fig. 5) shows a branching of the third anal vein 

 of the hind wing, similar to that in Micropterygidae and 

 Trichoptera. 



It has just been shown that certain essential features of 

 venation common to Micropterygidae and Trichoptera and 

 seemingly found in no other insects can be identified in more or 

 less modified form in most of the more primitive Lepidoptera. 

 In most cases the steps in this process of modification can be 

 traced. The evidence is perhaps least satisfactory in the 

 Hepialidae, which would indicate their divergence from the other 

 lepidopterous groups, a view borne out by other points of 

 structure. It is apparent that these characteristic features 

 of venation which the Micropterygidae hold in common with the 

 Trichoptera do not distinguish them from the rest of the 

 Lepidoptera as sharply as might be inferred by a comparison 

 of the Micropterygidae with more specialized Lepidoptera only. 

 The manner of specialization in the Nepticulidae, with respect 

 to the course of cubitus, is of especial value in determining 

 the true phylogenetic relationship of the Micropterygidae to 

 the rest of the Lepidoptera. The coiirse of modification in 

 the more generalized Nepticulidae, paralleling that sometimes 

 occurring in Trichoptera, which is a divergence from, the 

 usual lepidopterous type, together with the possession of the 

 fibula, undoubtedly indicates a common ancestry with Trichop- 

 tera, while certain other typically lepidopterous characters, 

 such as the single spined frenulum of the male, the short tongue 

 and six-jointed maxillary palpi characteristic of many primitive 

 Frenatag, gbsolescence of the first anal vein of the fore wing, 

 the reduction of radius of the hind wing in the same manner as 

 it has taken place in the Frenatae, place the Nepticulidae with 

 certainty in the Lepidoptera. This peculiar combination of 

 characters in the Nepticulidae, taken in connection with the 

 undoubted specialization in venation, places them as the end 

 group of a line of development divergent from that of the other 

 Lepidoptera. Since these two divergent lines of development 

 are both lepidopterous, the common ancestor must also be 

 lepidopterous. It has just been shown, that the course of 

 modification in venation in both lines of development can be 

 traced back to Micropterygidae, which therefore, on the basis 

 of evidence derived from a study of venation, must be regarded 

 as the common ancestor and is hence lepidopterous. To 



