[54] J. G. Wood, Natural History, p. 262.
[55] Westermarck, The History of Human Marriage, p. 11.
[56] Brehm, Bird-Life.
[57] Letourneau, The Evolution of Marriage and the Family, p. 27.
[58] Ibid., p. 35.
[59] Darwin, The Descent of Man, p. 590.
[60] Letourneau, The Evolution of Marriage and the Family, p. 32.
[61] Anthropology, p. 405.
[62] Life in Abyssinia, vol. ii., p. 152.
[63] Tylor, Anthropology, p. 406.