36 
ELEMENTS OF ENTOMOLOGY, 
clearly exemplified in that description of wings which is usually term- 
ed transparent, as in the common house-fly and the bee. The true 
wing, by means of which the insect is enabled to fly, is always con- 
structed in this manner, whatever may be its appearance externally, 
arising from a superficial covering of down, feathers, hair, or any other 
cause. The variety in the form and structure of the wings, in the 
number, figure, and disposition of the nervures, or the colours with which 
they are adorned, is infinite. The diversity’ in the disposition of the 
nervure is evident from a comparison of the simply constructed wing of 
the common house-fly with the complex wing of the Panorpa or the 
Ephemera, or the wings of an earwig, which consists of a series of sin- 
gle nervure, with the elaborately wrought lattice-work of the wing of the 
Libellula. The whole of the lepidopterous order exhibit the superficial 
coating of feathers, down, or hairs; and upon the removal of these the 
wings are found constructed in the same manner as the transparent 
wings of the ot her orders. A varia tion in the form of the wing as well 
as its texture is manifest throughout ail insects of the winged kind. 
Those of the Caleoptera have two membranaceous wings, which fold 
upon each oilier, forming a plait or double at their external margin, 
which fold is accommodated by a peculiar joint in the main rib of 
the wing, and the disposition of the nervures in the middle of the wing 
contiguous. In the Hemiplcru the wings generally fold longitudinally', 
without any transverse double; so that in expansion these parts open 
somewhat Jikea fan. I he anterior wings of the Lepidoptera are neither 
doubled across nor folded longitudinally’; they’ are entirely flat, and 
arc but little capable of contraction and dilatation. In the genus Pa- 
pilio they are endowed with the power of erection, which is rarely the 
case in the Phalena, though occasionally observed among the Sphin- 
ges; the Phaltena- have the lower wings concealed under the anterior 
pair, flic latter being laid in a flat position over them. The wings of 
the Lepidoptera are downy, and often decorated with very beautiful 
colours disposed in the most pleasing and varied manner. The Neu- 
roptera in general have the wings flat; this is not invariable; they are 
constantly membranaceous, and reticulated with nervures. In the 
Hymenoptera the wings are membranaceous, generally flat, but some- 
times folded when the insect settles, as in the wasp genus. The Dipte- 
rous order cannot be confounded with the preceding, as they have only- 
two wings : they are membranaceous as in die former. 
In all insects of the winged kind these organs present the greatest 
diversity, and afford characters both for genera and species less liable 
to fluctuation than common observers would conceive. The number, 
figure, construction, proportion, consistence, and texture of the wings 
have enabled naturalists to distribute insects into principal groups 
with considerable precision. Linne derived much assistance from an 
