No. 376.] THE WINGS OF INSECTS. — 255 
families, there is more vein-material here than is necessary or 
perhaps desirable, for we find a very general tendency towards 
the atrophy of the base of the media. 
An excellent record of what has taken place is preserved in 
the fore wing of the adult of Anosia (Fig. 26). Here the base 
of the media has disappeared, but there remain three little spurs 
projecting back into cell R-+-/V/ (indicated by the arrows) which 
show the positions occupied by the three branches of the media 
when the base of this vein ceased to be of use. It should be 
2d A 
Fic. 26.— Fore wing of Anosia. 
observed that in the pupa of this butterfly the medial trachea 
is well preserved throughout its entire length; the atrophy of 
the base of the media pertains only to the adult state.’ 
Correlated with the atrophy of the base of the media, there 
arises a necessity for a new source of air supply for the medial 
area of the distal half of the wing of the adult, and probably 
also for a better bracing of this part of the wing than would 
exist if no other changes were made. These are furnished by 
a more intimate connection of the branches of the media with 
the adjacent veins, vein Mı becoming more intimately con- 
nected with the radial sector, vein M} with cubitus-one, and 
vein Mz with one or the other of these veins, differing in dif- 
ferent families. 
There result from the changes just pointed out striking 
modifications of the courses of the veins concerned. Note, for 
example, that the base of vein M, in Anosia (Fig. 26) has 
1 Figures of the wings of pupæ of Lepidoptera are omitted, as several have 
been published by Spuler and others. 
