Identifier: descentofmansele01darw (find matches)
Title: The descent of man, and selection in relation to sex
Year: 1871 (1870s)
Authors: Darwin, Charles, 1809-1882
Subjects: Evolution Natural selection Heredity Human beings -- Origin Evolution
Publisher: London, J. Murray
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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hich serves as the fiddle itself. One ofthe nervures (a) on the under surface of the former isfinely serrated, and is scraped across the prominentnervures on the upper surface of the opposite or rightwing. In our British Pliasgonura viridissima it ap-peared to me that the serrated nervure is rubbedagainst the rounded hind corner of the opposite wing,the edge of which is thickened, coloured brown, andvery sharp. In the right wing, but not in the left,there is a little plate, as transrjarent as talc, surroundedby nervures, and called the speculum. In Ephippig&rvitium, a member of this same family, we have a curious 3:- Zeitsehrift fur wissenschaft. Zoolog. B. xvii. 18G7, s. 117.:i3 Westwood, Modern Class, of Insects, vol. i. p. 440. Chap. X. ORTHOPTERA. 355 subordinate modification; for the wing-covers are greatlyreduced in size, but the posterior part of the pro-thorax is elevated into a kind of dome over the wing-covers, and which has probably the effect of increasing the sound.34
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Fig. 12. (Jblorocoilus Tanana (from Bates), a, b. Lobes of opposite wing-covers. We thus see that the musical apparatus is moredifferentiated or specialised in the Locustidse, whichincludes I believe the most powerful performers inthe Order, than in the Achetidse, in which both wing-covers have the same structure and the same function.35Landois, however, detected in one of the Locustidse,namelv in Decticus, a short and narrow row of small 31 Westwood, Modern Cla&s. of Insects, vol. i. p. 453.35 Landois, ibid. s. 121,122. 2 a 2 356 SEXUAL SELECTION. Part II. teeth, mere rudiments, on the inferior surface of theright wing-cover, which underlies the other and isnever used as the bow. I observed the same rudi-mentary structure on the under side of the right wing-cover in Phasgonura viridissima. Hence we may withconfidence infer that the Locustidaa are descended froma form, in which, as in the existing Achetidas, bothwing-covers had serrated nervures on the under surface,and could be i

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