BY R. J. TlLLYARlJ. 401 



Turning now to the Orders Lepidoptera and Planipennia, we 

 see that both of tliese preserve the complete set of tracheie in the 

 pupal wing. In this character, then, they are both of them 

 much more archaic than the Mecoptera and the other three 

 Orders discussed above. It must be clear, therefore, on this 

 character alone, that the Lepidoptera cannot be descended either 

 from the Mecoptera, as Handlirsch supposed, or from the Tri- 

 choptera, as Meyrick would have it. 



Let us now return to the question of the interpretation of the 

 imaginal wing-venation in Chorista. The tracheation having 

 failed us, what other evidence have we to go upon in working 

 this out? 



First of all, it may be stated that the main scheme of venation 

 in Chorista^ like that of the Trichoptera, is so primitive that 

 there can be no hesitation in naming the veins, even though we 

 cannot call upon the trachea? as evidence. The subcosta, the 

 radius, the radial sector with its dichotomous branches, and the 

 anal veins can all be named without any misgivings. It is only 

 the media and cubitus that offer a difficult problem. By re- 

 ferring to Text-fig. 1, it will be seen that the main stem of the 

 media, in both fore- and hind wings, is continued straight on by 

 a strongly convex vein right to the wing-border. All the rest 

 of the media lies anteriorly to this. The media being properly 

 a concave vein, it follows that there is at once a strong supposi- 

 tion that this straight prolongation of the media is really Cuj, 

 and that the result has been brought about by a fusion of this 

 latter vein, not far from its original at the cubital fork, witli the 

 main stem of the media. 



If we examine the imaginal venation carefully, we shall see at 

 once strong evidence in favour of this view. Picking up the 

 base of the cubitus, which is a very weakly chitinised vein, and 

 following it to the cubital fork (en/), we see that the apparent 

 cross-vein from this point to the media may very well be the 

 basal portion of Cuj, arching up to unite with the media at the 

 point k; and then leaving it again as the straight, strong, convex 

 vein in question. If that be so, then Cuo hi the forewing is the 



