. The descent of man, and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings; Sexual selection in animals; Sexual dimorphism (Animals); Sex differences. INSECTS. 323 the wing-covers, and which has probably the effect of increasing the sound/'* We thus see that the musical apparatus is more dif- ferentiated or specialized in the Locustidae (which include, I believe, the most powerful performers in. ^g. 13. Chlorocoelus Tanana (from Bates). «, 6. Lobes of opposite wing-coTers. the order), and in the Achetidae, in which both wing- covers have the same structure and
. The descent of man, and selection in relation to sex. Evolution; Natural selection; Heredity; Human beings; Sexual selection in animals; Sexual dimorphism (Animals); Sex differences. INSECTS. 323 the wing-covers, and which has probably the effect of increasing the sound/'* We thus see that the musical apparatus is more dif- ferentiated or specialized in the Locustidae (which include, I believe, the most powerful performers in. ^g. 13. Chlorocoelus Tanana (from Bates). «, 6. Lobes of opposite wing-coTers. the order), and in the Achetidae, in which both wing- covers have the same structure and the same function ]- Landois, however, detected in one of the Locustidae, namely in Decticus, a short and narrow row of small teeth, mere rudiments, on the inferior surface of the right wing-cover, which underlies the other and is never used as the bow, I observed the same rudimentary structure on the under side of the right wing- cover in Phasgonura viridissima. Hence we may infer with confidence that the Locustidae are descended from a form ip which, as in the existing Achetidae, both wing- ?Westwood, "Modern Class, of Insects," vol. i, p. 453 t Landois, ''Zeitsch. t wiss Zoylo^/' B. xvU, 1867, ss. 12t 12?. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York : A. L. Burt
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