This lateral fold encloses the flank of the abdomen and is covered with fine oblique and parallel nervures.
The powerful nervures of the dorsal portion of the wing-cover are of the deepest black, and their general effect is that of a complicated design, not unlike a tangle of Arabic caligraphy.
Seen by transmitted light the wing-cover is of a very pale reddish colour, excepting two large adjacent spaces, one of which, the larger and anterior, is triangular in shape, while the other, the smaller and posterior, is oval.

Each space is surrounded by a strong nervure and goffered by slight wrinkles or depressions.

These two spaces represent the mirror of the locust tribe; they constitute the sonorous area.

The substance of the wing-cover is finer here than elsewhere, and shows traces of iridescent though somewhat smoky colour.
These are parts of an admirable instrument, greatly superior to that of the Decticus.

The five hundred prisms of the bow biting upon the ridges of the wing-cover opposed to it set all four tympanums vibrating at once; the lower pair by direct friction, the upper pair by the vibration of the wing-cover itself.