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Show 200 SEXUAL SELECTION : BlllDS. PART II. tions in brightness which occurred in the females or in the young would have been of no service ~o them, and would not have been selected; moreover, If dangerous,. would have been eliminated. Thus the females and the young wm either have been left unmodi~ed, or, and this bas much more commonly occurred, Wlll have been partially modified by receiving through transference from the males some of the successive variations. Both sexes have perhaps been directly acted on by the conditions of life to which they have long been exposed; but the females from not being otherwise much modified will best exhibit any such effects. These changes and all others will have been kept uniform by the free intercrossing of many individuals. In some caRes, especially with ground birds, the females and the young may possibly have been modified, independently of the males, for the sake of protection, so as to have acquired the same dull-coloured plumage. CLASS II. When the adult female is more conspicuous than the adult male, the young of both sexes in their first plumage resemble the adult male.-This class is exactly the reverse of the last, for the females are here more brightly coloured or more conspicuous than the males; and the young, as far as they are known, resemble the adult males instead of the adult females. But the difference between the sexes is never nearly so great as occurs with many birds in the first class, and the cases are comparatively rare. Mr. ·wallace who first called attention to the singular relation which exists between the less bright colours of the males and their performing the duties of incubation, lays great stress on this point/3 as a crucial test that obscure colours have 18 'Westminster Review,' July, 1867, and A. Murray, 'Journnl of Travel,' 1868, p. 83. CliAP. XVJ. 'l'IIE YOUNG LIKE TilE ADULT :1\IALES. 201 beo~1 acquire~ for the .sake of protection during the pcrwd of nestmg. A chfferent view seems to me more probable. As the cases are curious and not numerous I will briefly give all that I have been able to find. ' In one section of the genus Turnix, quail-like birds the femal.e is invaria~ly larger than the male (bein~ nearly .t':Ice as large I.n one of the Australian species) and tlns Is an unusual Circumstance with tl1e Gallinacere. In most of the species the female is more distinctly coloured and brighter than the male,14 but in some few species the sexes are alike. In Turnix taiqoor of India the male " wants the black on the throat and neck "aud the whole tone of the plumage is lighter and les~ "pronounced than that of the female." The female appears to b~ more vociferous, and is cer.tainly much more pugnaciOus than tho male; so that the females and not the males are often kept by the natives for fighting, 'like game-cocks. As male birds are exposed ?Y the English bird-catchers for a decoy near a trap, m order to catch other males by exciting their rivalry, so the females of this Turnix are employed in India. When thus exposed the females soon begin their "loud "purring call, which can be heard a long wny off, "and any females within ear-shot run rapidly to the " spot, and commence :fighting with the caged bit·d.'' In this way from twelve to twenty birds, all breedingfemales, may be caught in the course of a single day. The natives assert that the females after laying their eggs associate in flocks, and leave the males to sit on them. There is no reason to doubt the truth of this assertion, which is supported by some observa- 14 For the Australian species, see Gould's • Handbook,' &c., vol. ii. p. 178, 180, 186, and 188. In the British Museum specimens of the :Aust~al~an Plain-wanderer (Pedionomus torquatus) may be seen, showmg s1mllnr sexual differences. |