[8] Fishes were first introduced in the later Silurian; but became dominant in the Devonian.

[9] Amphibians were introduced in the Carboniferous, but true reptile not until the Permian.

[10] Of course I mean downward in social function. Individually the scavenger may be nobler than the statesman.

[11] Cope, “Science,” vol. ii, p. 274, 1883.

[12] Boston Society of Natural History—anniversary memoir, 1880. Also, “American Naturalist,” June, 1882.

[13] “Archives des Sciences,” vol. liv, 1875.

[14] “Nature,” vol. xxxi, p. 4, 1884.

[15] See abstract of Dr. Romanes’s views, “Nature,” vol. xxxiv, pp. 314, 336, 362. Also, discussions of the same by Meldola, Galton, Wallace, etc., in immediately subsequent numbers.

[16] This subject is more fully treated in chapter IX, p. 240 et seq.

[17] See an article entitled “Genesis of Sex,” “Popular Science Monthly,” 1879, vol. xvi, p. 167.