92 Lyell, B. i. c. iii. p. 67. (4th ed.)

93 B. iii. c. xiii. xiv. xv. xvi. xvii.

94 Lyell, B. iii. c. xvii. p. 286. See also his Address to the Geological Society in 1837, for an account of the Researches of Mr. Stokes and of Professor Göppert, on the lapidification of vegetables.