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Now the great locust has only to harden its tissues a little longer and to tan the grey of its costume in the ecstasy of the sunshine. Let us leave it to its happiness, and return to an earlier moment. The four stumps which emerge from their coverings shortly after the rupture of the corselet along its median line contain, as we have seen, the wings and elytra with their innumerable nervures.
Its inner edge carries, on the under side, near the base, a callosity from which five radiating nervures proceed; two of them upwards and two downwards, while the fifth runs approximately at right angles to these.
In the dragon-flies, the nervures are minutely netted for the sake of increased strength; in the bees, the nervures are simply parallel. Most insects have two pairs of these transparent membraneous wings; but in such as burrow, one pair is converted into a dense leather-like case, under which the other pair are folded away.
He says, "It is remarkable for having a sort of drum at the base of the fore wings, between the costal nervure and the subcostal. These two nervures, moreover, have a peculiar screw-like diaphragm or vessel in the interior." The noise was continued at short intervals, and could be distinguished at about twenty yards' distance: I am certain there is no error in the observation.
In the crickets the wing-cases are symmetrical; both have straight edges and sharply-scored nervures adapted to produce the stridulation. A distinct portion of their edges is not, therefore, set apart for the elaboration of a sound-producing instrument. In this family the wing-cases lie flat on the back of the insect, and overlap each other for a considerable portion of their extent.
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