584 THE PANORPOJD COMPLEX, iii., 



dition is that seen in the Orthoptera. I know of no pupal 

 wings in which the three anal veins lie widely separated upon 

 the alar trunk trachea. Even in the Planipennia and Lepi- 

 doptera, where they are certainly separate, they lie close to- 

 gether upon this trunk, and are easily distinguished as a separate 

 group. Considering how greatly all the tracheae are split back 

 in the Lepidoptera, even R and M often appearing to arise a& 

 two distinct tracheae from the alar trunk, it would surely seem 

 more logical to take as the more archaic condition that in which 

 the three tracheae arose from a single base upon the alar trunk, 

 a condition from which all the above described states could 

 easily be derived. 



It seems necessary to emphasise this, since otherwise it is 

 hard to understand why the three anal veins should form an 

 exception to the usual rule of alternate convex and concave veins. 

 The fact that they are all three convex certainly points strongly 

 to their being all branches of a single anal vein. 



It should be noted that I do not consider Comstock's 1A in 

 Homoptera to be that vein, any more than it is in Lepidoptera. 

 It is certainly Cu 2 , and the cubitus is three-branched in both 

 these Orders. The Y-vein on the clavus of the Fulgoroidea is 

 strictly homologous with the anal Y-vein of the Lepidoptera, and 

 is formed by the looping-up of 2A on to 1A. 



Section vi. The Distal Y-Vein, Trigamma, Basal Cell and 

 Areole in the Lepidoptera. 



(Plate xxxiv., fig. 21, Plate xxxv., fig. 23, and Text-figs. 55-59.) 



When this research was begun, in 191C, it was recognised that 

 one of the most interesting problems to be studied was the 

 evolution of the Lepidopterous type of wing. At that time, the 

 fossil Archipanorpa was known, but Belmontia had not been 

 discovered. I saw, then, in the Protomecopterous type of wing- 

 venation, the ancestral form from which the Lepidopterous type 

 could best be derived; and I published a short Preliminary Re- 

 port ( 13) in which this idea was followed out. Since then, 

 the discovery of Belmontia, and the large amount of time that 

 I have given to researches upon the Lepidoptera, have con- 

 vinced me that it is the Parameeoptera which are the true an- 

 cestral Order from which the Lepidoptera have been derived 

 (20). 



