The Descent of Man

In the last and third family, namely the Acridiidae
or grasshoppers, the stridulation is produced
in a very different manner, and according
to Dr. Scudder, is not so shrill as in the
preceding Families. The inner surface of the
femur (Fig. 14, r) is furnished with a longitudinal
row of minute, elegant, lancet-shaped, elastic
teeth, from 85 to 93 in number (40. Landois,
ibid. s. 113.); and these are scraped across the
sharp, projecting nervures on the wing-covers,
which are thus made to vibrate and resound.
Harris (41. 'Insects of New England,' 1842, p.
133.) says that when one of the males begins to
play, he first "bends the shank of the hind-leg
beneath the thigh, where it is lodged in a furrow
designed to receive it, and then draws the
leg briskly up and down. He does not play both
fiddles together, but alternately, first upon one
and then on the other." In many species, the
base of the abdomen is hollowed out into a
great cavity which is believed to act as a resounding
board. In Pneumora (Fig. 15), a S.