[xxi-A] Preface to 5th ed. of Studies of University of Cambridge.

[xxii-A] Principles, 4th ed. 1835, vol. i. p. 231, and vol. i. chap. 9. subsequent ed.

[xxii-B] In my Anniversary Address, for 1851, to the Geological Society, the reader will find a full discussion of the facts and arguments which bear on the theory of progressive development.—Quart. Journ. Geol. Soc., vol. vii.

[3-A] See Principles of Geology, by the Author, Index, "Nile," "Rivers," &c.

[4-A] See [p. 18.]

[4-B] See Geograph. Journ. vol. iv. p. 64.

[11-A] The kaolin of China consists of 71·15 parts of silex, 15·86 of alumine, 1·92 of lime, and 6·73 of water (W. Phillips, Mineralogy, p. 33.); but other porcelain clays differ materially, that of Cornwall being composed, according to Boase of nearly equal parts of silica and alumine, with 1 per cent. of magnesia. (Phil. Mag. vol. x. 1837.)

[11-B] See W. Phillips's Mineralogy, "Alumine."

[14-A] Consult Index to Principles of Geology, "Stratification," "Currents," "Deltas," "Water," &c.

[21-A] Siau. Edin. New Phil. Journ. vol. xxxi.; and Darwin, Volc. Islands, p. 134.