[168] See especially Osborn and Wortman, Bull. Amer. Mus. Nat. Hist. vii. 1895, p. 333, and Osborn, ibid. viii. 1896, p. 157.
[169] See Osborn, Bull. Amer. Mus. Nat. Hist. vii. 1895, p. 82.
[170] N. Acta Acad. Caes. Leop. Car. xxvii. 1885, p. 238.
[171] See Bateson, Materials for the Study of Variation, London, 1894, p. 387.
[172] See, however, p. [196], for a discussion as to which is the more primitive arrangement.
[173] Titanotherium (see p. [266]) is exceptional.
[174] Bones of Hippopotamus, however, indicate the very recent occurrence of that animal in Madagascar.
[175] "On the Pygmy Hippopotamus of Liberia," Proc. Zool. Soc. 1887, p. 612.
[176] Tomes, Proc. Zool. Soc. 1850, p. 160.
[177] There is, however, some doubt about the first premolars.