[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.