[2] Hartung, Die Azoren, 1860; also Insel Gran Canaria, Madeira und Porto Santo, 1864, Leipsig.

[3] Geognost. Beschreib. des Siebengebirges am Rhein. Bonn, 1852.

[4] Scrope’s Central France, p. 98.

[5] Principles of Geology, chap. xxvi, 9th ed., p. 432.

[6] Boblaye and Virlet, Morea, p. 23.

[7] De la Beche, Geol. Proceedings, vol. ii, p. 198.

[8] Maclaren, Geology of Fife and Lothians. Geikie, Trans. Royal Soc. Edinburgh, 1860-1861.

[9] Murchison, Silurian System, etc., p. 230.

[10] Ibid., p. 212.

[11] Murchison, Silurian System, etc., p. 325.