AcanthopsycJie opacella. 409 



persistent, and always reaches the margin of the wing. 

 The third or inner one, thougli very constant and well 

 within the wing area at an early stnge, soon becomes quite 

 a marginal vein, and does not so far as I know leave any 

 trace in the imaginal wing. The second or intermediate 

 one (la of Meyrick and Hampson, 3rd anal of Comstock) 

 may or may not persist in the imago, it usually joins the 

 first near the base, and there are very few exceptions (if 

 any) to the rule that it never reaches the margin of the 

 wing. In Psyche this vein joins the 2nd anal (lb) in the 

 manner that is so very usual, but further on appears to 

 leave it again and proceed to the inner margin, forming 

 one of the exceptions I have alluded to where this vein 

 does not follow the rule of failing to reach the margin. 



In the case of A, opacella, I have succeeded in examining 

 the pupal wing at a suitable late stage, when the relation- 

 ship of the primary pupal trachese to the imaginal veins is 

 obvious. In these examples the trachea of the 3rd anal 

 (la) is short and occupies the position of the lower loop of 

 the bifurcation, without quite reaching the 2nd anal (Ic). 

 At about this point the 2nd anal trachea divides into two 

 stems which keep together for a short distance and then 

 one goes on in the normal course of that vein, the other 

 proceeds more directly to the inner margin, forming the 

 inner vein so characteristic of the Psychids. The im- 

 portant point is that this vein is not a continuation of the 

 3rd anal (la) after coalescing for a time with the 2nd (lb), 

 but is a new development of that vein. It clears away 

 this one apparent exception to the rule that the Srd anal 

 never reaches the wing margin. In the CEketicids there 

 are several veins in this position, two, three, or even more, 

 though it is clear these could not all be a simple continua- 

 tion of the 3rd anal (la); tliis observation on A. opacella 

 renders it tolerably certain that they are all fresh develop- 

 ments of the 2nd anal. A small tracheal twig from the 

 2nd anal marks the place of anastomosis with the 1st 

 anal (Ic). 



As regards the hindwings A. opacella presents nothing 

 having a very wide significance. But its special place in 

 the scheme of evolution of the anterior veins of the hind- 

 wing arc possibly important. My few observations on 

 these appear to suggest that the primary frenate subcosta 

 (8 of Meyrick and Hampson) was formed by the union of 

 the true subcostal vein, with the first branch of the radius 



