[253] For the Milvago, see ‘Zoology of the Voyage of the “Beagle,”’ Birds, 1841, p. 16. For the Climacteris and nightjar (Eurostopodus), see Gould’s ‘Handbook of the Birds of Australia,’ vol. i. p. 602 and 97. The New Zealand shieldrake (_Tadorna variegata_) offers a quite anomalous case: the head of the female is pure white, and her back is redder than that of the male; the head of the male is of a rich dark bronzed colour, and his back is clothed with finely pencilled slate-coloured feathers, so that he may altogether be considered as the more beautiful of the two. He is larger and more pugnacious than the female, and does not sit on the eggs. So that in all these respects this species comes under our first class of cases; but Mr. Sclater (‘Proc. Zool. Soc.’ 1866, p. 150) was much surprised to observe that the young of both sexes, when about three months old, resembled in their dark heads and necks the adult males, instead of the adult females; so that it would appear in this case that the females have been modified, whilst the males and the young have retained a former state of plumage. [254] Jerdon, ‘Birds of India,’ vol. iii. p. 598. [255] Jerdon, ‘Birds of India,’ vol. i. p. 222, 228. Gould’s ‘Handbook of the Birds of Australia,’ vol. i. 124, 130. [256] Gould, Ibid. vol. ii. p. 37, 46, 56. [257] Audubon, ‘Ornith. Biography,’ vol. ii. p. 55. [258] ‘Variation of Animals and Plants under Domestication,’ vol. ii. p. 79. [259] Charlesworth, ‘Mag. of Nat. Hist.’ vol. i. 1837, p. 305, 306. [260] ‘Bulletin de la Soc. Vaudoise des Sc. Nat.’ vol. x. 1869, p. 132. The young of the Polish swan, _Cygnus immutabilis_ of Yarrell, are always white; but this species, as Mr. Sclater informs me, is believed to be nothing more than a variety of the Domestic Swan (_Cygnus olor_). [261] I am indebted to Mr. Blyth for information in regard to this genus. The sparrow of Palestine belongs to the sub-genus Petronia. [262] For instance, the males of _Tanagra æstiva_ and _Fringilla cyanea_ require three years, the male of _Fringilla ciris_ four years, to complete their beautiful plumage. (See Audubon, ‘Ornith. Biography,’ vol. i. p. 233, 280, 378.) The Harlequin duck takes three years (ibid. vol. iii. p. 614). The male of the Gold pheasant, as I hear from Mr. J. Jenner Weir, can be distinguished from the female when about three months old, but he does not acquire his full splendour until the end of the September in the following year. [263] Thus the _Ibis tantalus_ and _Grus Americanus_ take four years, the Flamingo several years, and the _Ardea Ludovicana_ two years, before they acquire their perfect plumage. See Audubon, ibid. vol. i. p. 221; vol. iii. p. 133, 139, 211. [264] Mr. Blyth, in Charlesworth’s ‘Mag. of Nat. Hist.’ vol. i. 1837, p. 300. Mr. Bartlett has informed me in regard to gold-pheasants.