[36] Bronn’s Klassen u. Ordnungen des Thierreichs, vol. iii. p. 466.
[37] Weismann, The Duration of Life, in “Essays on Heredity” (English translation), Oxford, 1889.
[38] Oustalet, “La Longévité chez les Animaux vertébrés,” La Nature, May 12, 1900, p. 378.
[39] “On the Comparative Ages to which Birds live,” The Ibis, Jan., 1899, vol. v. p. 19.
[40] J. Maumus, “Les cæcums des oiseaux,” Annales des sciences naturelles, 902. See also P. Chalmers Mitchell, “On the Intestinal Tract of Birds,” Trans. Linnæan Soc. of London, vol. viii. part 7, 1901.
[41] Weidersheim, Elements of the Comparative Anatomy of Vertebrates, translated by W. Newton Parker, p. 236, 1886.
[42] Elements of Comparative Anatomy, English translation by F. Jeffrey Bell, B.A., London, 1878, p. 562.
[43] Virchow’s Archiv, 1869, vol. xlviii. p. 151.
[44] P. Chalmers Mitchell, “On the Intestinal Tract of Mammals,” Trans. Zool. Soc. of London, vol. xvii. part 5, 1905.
[45] Travaux de la Société des médecins russes à Saint-Pétersbourg. September-October, 1905, p. 18 (in Russian).