Archive image from page 297 of The descent of man . The descent of man : and selection in relation to sex descentofmanseledarw Year: 1874 284 THE DESCENT OF MAN. Fig. 14. Hind-leg of Stenoboth- rus pratorum: r, the stridu- lating ridge; lower figure, the teeth forming the ridge, much magnified (from Landois). elastic teeth, from 85 to 93 in number;' and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and re- sound. Harris' says that when one of the males begins to play, he first 'bends the shank of 'the hind-leg beneath the thigh,
Archive image from page 297 of The descent of man . The descent of man : and selection in relation to sex descentofmanseledarw Year: 1874 284 THE DESCENT OF MAN. Fig. 14. Hind-leg of Stenoboth- rus pratorum: r, the stridu- lating ridge; lower figure, the teeth forming the ridge, much magnified (from Landois). elastic teeth, from 85 to 93 in number;' and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and re- sound. Harris' 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. African genus belonging to the same family, we meet with a new and remarkable modification; in the males a small notched ridge projects obliquely from each side of the abdomen, against which the hind femora are rubbed. As the male is furnished with wings (the female being wingless), it is remarkable that the thighs are not rubbed in the usual manner against the wing- covers; but this may perhaps be accounted for by the unusually small size of the hind-legs. I have not been able to examine the inner surface of the thighs, which, judging from analogy, would be finely serrated. The species of Pneumora have been more pro- foundly modified for the sake of stridulation than any other orthopterous insect; for in the male the whole body has been converted into a musical instrument, being distended with air, like a great pellucid bladder, so as to increase the resonance. Mr. Trimen informs me that at the Cape of Good Hope these insects make a wonderful noise during the night. In the three foregoing families, the females are almost always
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