582 THE PANORPOID COMPLEX, tii., 



already dealt with above (p. 577). Text-fig. 54 will explain this 

 formation, which, as tar as I am aware, has remained quite un- 

 noticed by all Lepidopterists and students of wing-venation up 

 to the present day. The most archaic stage is to be seen in 

 Xyleutes (Text-fig's. 546, 87) . In tins genus, when trachea 1A 

 diverges from Cua, after its approach to it more basally, it 

 converges towards trachea 2A, until they come to lie alongside 

 one another for a short distance about the middle of their 

 lengths. It then diverges again from 2A, but fails to reach 

 the wing border. In the imaginal venation (Text-fig. 88), all 

 that part of 1A lying distad from the fusion with 2A fails to 

 become chitinised. Moreover, the basal portions of the two 

 veins are withdrawn towards the base of the wing, so that the 

 final result is a small basal Y-vein, of much the same type as 

 that seen in the highest stages of evolution of the same Y-vein 

 in the forewing (as in the Butterflies). 



An examination of the venation of the Superfamily Tor- 

 tricina shows that this Y-vein formation is almost universally 

 present in the hindwings of this group. The precedent forma- 

 tion in the pupal wing is well shown in Carpocapsa (Text-figs. 

 54c, 89) . Here we notice a slight advance upon the condition 

 shown in 'Xyleutes, in that trachea 1A is much shortened, and 

 only just succeeds in reaching 2A after diverging from Cu 2 , 

 But the resulting formation in the imaginal venation (Text-fig. 

 54, d) is practically the same as in Xyleutes. 



In the Superfamily Tineina, this basal Y-vein of the hind- 

 wing is only to be seen in a few archaic genera. In examining 

 the hindwing of Wingia (Text-fig. 93) I was just able to make 

 it out as a weakly chitinised formation in the imago. Turning 

 to the pupal tracheation, I was very surprised to find that 

 trachea 1A was well formed and complete, from base to wing- 

 border, and that it maintained its basal contact with Cu 2 intact. 

 There was no sign whatever of trachea 2A, and the course of 

 that vein in the imaginal wing was indicated only by the usual 

 pale band. If this be the usual condition in the Tineina, it 

 indicates a clear dichotomy between them and the Tortricina ; 

 for, in the latter, it is trachea 1A which becomes reduced, 

 whereas in Wingia the same fate befalls ti"achea 2A. While 

 further researches are needed on this point, it should be noted 

 that, whereas the Y-vein is retained almost throughout the whole 

 of the Totricina, it is soon lost in the Tineina, the great ma- 



