620 EXTERNAL ANATOMY OF INSECTS. 
&c., are of a firmer substance than those of the other 
Orders ; in many Locusta, Fulgore, &c., they are nearly 
as firm as the ¢egmina,; and in Ascalaphus italicus, ex- 
cept at their base, the secondary wings are less membra- 
nous than the primary. M. Chabrier has observed * 
that the wings of insects in general diminish in thickness 
from their base to their apex, and from their anterior to 
their posterior margin. 
3. I should have had, it is probable, but little original 
matter to communicate under the head of the composition 
and neuration of wings, had M. Jurine, who has written 
so ably on those of Hymenoptera, undertaken a survey of 
the organs of flight in every Order of insects: but as his 
views were confined to only ¢wo of the Linnean Orders, 
it is not wonderful that his system and set of terms should 
fail where a generalization is necessary ; and I may stand 
acquitted of presumption and conceit if I attempt to sub- 
stitute a system and body of terms more universally ap- 
plicable. Had the plan of this able Entomologist led 
him to pay attention to ¢egmina and hemelytra, their 
division into three longitudinal areas would have imme- 
diately struck him; and having acquired this outline of 
the greater natural divisions, he would have applied it to 
the Orders that have wings only, and having discovered 
that it is to be traced in all, the result would have pro- 
bably superseded my labours. Had his life been longer 
spared, perhaps something of this kind would have been 
effected by him; but ashe, alas! is gone, and no abler 
hand seems to have undertaken the task, I will do what 
I can to give you satisfaction on this subject”. You 
2 Sur le Vol des Ins. c. i. 424. 
> The idea of dividing the wing of an insect into larger areas seems 
first to have been acted upon in Monogr. Apum Angé. (1801), in which 
