684 THE PANORPOID COMPLEX, tiL, 



R 4) is really the radial cell or areole, which has become sessile 

 upon R, owing to the separation of R2+3 anc ^ r *4+5 hasally. At 

 metamorphosis, not only all that part of trachea M, lying within 

 the basal cell, becomes aborted, but also the stem of R 4+5 , which 

 properly separates the areole from the basal cell. Thus, in the 

 imaginal forewing, the basal cell becomes an areocel, and is the 

 homologue of the basal cell of the Tortricina and Tineina. The 

 actual method by which this change is brought about is the 

 same as that already seen in Wingia, viz., a trachea from R 5 

 captures Mi, and another trachea from R 3 captures R 4 and 

 R 5 . Hence all the tracheae from R 4 to M x become hitched on to 

 R 3> , so that trachea R appears, at metamorphosis, as a trachea 

 having six branches all given off anteriorly in order. M 3 is 

 captured by CUj , as in Wingia. But M 2 loses its tracheal 

 supply, and fails to become annexed by either the radial or 

 cubital group of trachea?. 



In, the hindwing, Mj is captured by Rs at metamorphosis, and 

 M 3 by Cuj , But, as in the forewing, M 2 loses its tracheal 

 supply, and fails to become annexed to either group. Though 

 the vein M 2 is ehitinised in Eusehemon, it tends to become 

 aborted in many Hesperiidae, and its loss is primarily due to 

 the failure to secure a tracheal supply. 



Text-fig. 100 shows the imaginal venation of Eusehemon, for 

 comparison with Text-fig. 99. 



As a contrast to Eusehemon I studied the pupal tracheation 

 of one of the highly specialised Nymphalidae, Euploea corinna. 

 Text-fig. 101 shows the condition of the wings in a pupa 

 of this species about three days old, the veins and tracheae being- 

 indicated in the same manner as in Text-fig. 99. The only 

 important differences are as follows: — 



(1) In the forewing, I could find no sign of M 5 ; and M 1 _ 4 

 forks much closer to the base of the wing than in Eusehemon. 

 Also 2A is greatly reduced, and 3A completely absent. Besides 

 these differences, there is a fairly strong tracheal outgrowth 

 from Cu la along the vein M 4 towards M 3 . This is the same 

 outgrowth which appears in Eusehemon at metamorphosis. The 

 condition in Euploea is, then, an advance upon that seen in 

 Eusehemon. 



(2) In the hindwing, the condition of M is as in the forewing. 

 Ki comes off from the main stem of R in a highly specialised 

 manner, but is dominant over Sc. The latter trachea gives off a 



