VENATION OF THE WINGS. 
29 
costal nervure, that nearest the stigma being called 
the cubital nerve. It occurs either simple, once, or 
twice forked, and thus it is characteristic.* 
The cells of the wings in general take their names 
from the neighbouring veins, as shown hj the figure 
attached. 
In the genus Callipterus the nerves have a tendency 
to flatten or expand their diameters towards the apical 
margins of the wings. They then often have an 
elegant clouded or brocaded appearance. 
The wing membranes are exceedingly delicate, and 
so thin that they reflect all the prismatic colours of the 
soap-bubble. This character is more richly seen in 
some species than in others. Occasionally the mem- 
branes are finely punctured. 
The stigma is a broad expansion of the post-costal 
nerve, and connects the same with the costal. It 
forms the most coriaceous portion of the upper wing, 
and varies much in form and colour. Usually it is 
finely punctured, slightly scaly, or strongly imbri- 
cated.! 
Aphides show a peculiarity in folding their wings 
when at rest, which is not usually seen in other 
insects. 
In most genera they are carried vertically with the 
costal nerve placed downwards, and therefore not as in 
the diurnal Lepidoptera. 
In Vacuna, however, the position is different, for 
the wings almost overlap each other, and then they fold 
themselves horizontally, as in most of the Homoptera 
Heteroptera, and other orders of insects. 
* In Kaltenbach’s explanation of his fig. 7 the term cubitus is given 
to what I describe as the cubital nervure (d). That which I name the 
cubitus (a) he calls the under- marginal vein (unterrandader). 
t Vide Plate B, fig. 8. 
