. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. 284 THE DESCENT OF 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, "whe
. The descent of man : and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings. 284 THE DESCENT OF 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 "; 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 familie
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Keywords: ., bookcentury1800, bookdecade1870, booksubjecthumanbeings, bookyear
