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Show 358 SEXUAL SELECTION. PART IL in the male the whole body has been converted into a musical instrument, being distenrlecl with air, like a great pellucid bladder, so as to increase the resonance~ Mr. Trimcn informs me that at the Cape of Good Hope these insects make a wonderful noise during the night. Fig. 14. Pncumora (from specimens in the British Museum). Upptr figur~. mule ;. lower figure, female. - There is one exception to the rule that the females. in these three Families are destitute of an efficient musical apparatus; for both sexes of Ephippiger (Locustidro) are said 40 to be thus pmvided. This case may 40 Wcstwouu, iuid. Yol. i. p. 4.53. CHAP. X. ORTHOPTERA. 359 be compared with that of the reindeer, in which species alone both sexes possess horns. Although the female ortboptera are thus almost invariably mute, yet Landois·n found rudiments of the stridulating organs on the femora of the female Acridiidre, and similar rudiments on the under surface of the wing-covers of the female Achetidre; Lut he failed to find any rudiments in the females of Decticus, one of the Locustidre. In the Homoptera the mute females of Cicada, have the proper musical apparatus in au undeveloped state ; and we shall hereafter meet in other divisions of the animal kingdom with innumerable instances of structures proJ?er to the male being present in a rudimentary condition in the female. Such cases appear at first sight to indicate that both sexes were primordially constructed in the same manner, but that certain organs were subsequently lost by the females. It is, however, a more probable view, as previously explained, that the organs in question were acquired by the males and partially transferred to the females. Landois has observed another interestino- fact, namelv 0 • that in the females of the Acridiidre, the stridulating teeth on the femora remain throughout life in the same condition in which they first appear in both sexes during the larval state. In the males, on the other hand, they become fully developed and acquire their perfect structure at the last moult, when the insect is mature and ready to breed. From the facts now given, we see that the means Ly which the males produce their sounds are extremely diversified in the Orthoptera, and are altogether different from those employed by the Homoptera. But throughout the animal kingdom we incessantly find the 41 Landois, ibid. s. 115, 116, 120, 122. |