1919] Braun: Wing Structure of Lepidoptera 365 



comparison made only with more specialized groups of Lepi- 

 doptera. The modifications which are shown in the more 

 primitive groups of frenate Lepidoptera have their beginnings 

 in the Micropterygidas themselves. In addition we have 

 the evidence given by the Nepticulidse, which combine in one 

 group, certain characters found in the Frenatae, with characters 

 belonging to the Micropterygidae and in the manner of 

 specialization of certain characters of venation diverge from 

 all other Lepidoptera, paralleling what occurs in some 

 Trichoptera, The existence of these divergent groups, the 

 Frenatae and the Nepticulidae, both of which are derived 

 from Micropterygidae, is conclusive evidence of the lepidop- 

 terous character of their common ancestor, the Micropterygidae, 

 even if w^e do not take into consideration such features 

 of the Micropterygidas as the character of the mouth-parts and 

 the scale covering of the wings, which unmistakably stamp 

 them as lepidopterous. 



The conclusion drawn from a study of the various modes of 

 holding the wings together in flight in the Lepidoptera, is that 

 in the more primitive groups of Lepidoptera, including the 

 Micropterygidas, certain trichopterous structures are retained 

 and are functional, but in higher groups are modified or dis- 

 appear and their function is taken over by other wing structures, 

 chief of which is the frenulum. The frenulum in its specialized 

 form is shown to have had its origin in the Lepidoptera and to 

 have developed independently in several widely separated 

 groups. 



Certain general phylogenetic and taxonomic conclusions 

 follow from these studies. The Micropterygidae are close to the 

 common ancestor of both Lepidoptera and Trichoptera, but 

 are true Lepidoptera. From them the remaining Lepidoptera 

 have been derived, not from a single line of descent, but from 

 several divergent lines, one of which is represented by the 

 Nepticulidae alone; a second line by the Hepialidae, with the 

 Prototheoridas apparently forming a link between it and the 

 Micropterygidae, and to which the Cossidae show some degree 

 of relationship ; a third much branched line includes the frenate 

 Lepidoptera, of which some members such as the Prodoxidae, 

 Incurvariidas, etc., conserve some of the trichopterous char- 

 acters of their ancestry and must therefore be regarded as the 

 most primitive of the Frenatae. 



