[21] See Table I, p. 211, of Allen's Winter Birds of Florida.
[22] Proc. Zool. Soc., 1864, p. 64.
[23] J.A. Allen, on Geographical Variation among North American Mammals, Bull. U.S. Geol. and Geog. Survey, vol. ii. p. 314 (1876).
[24] Proc. Zool. Soc. Lond., 1864, p. 700, and 1868, p. 28.
[25] See Trans. Entomological Society of London, 1887, p. 24.
[26] Nature, vol. xix. p. 554.
[27] Nature, vol. xvi. p. 163; and vol. xi. p. 227.
[28] Ibid., vol. xxxi. (1885), p. 533.
[29] Nature, vol. xxvi. p. 81.
[30] Animals and Plants under Domestication, vol. ii. p. 258.