Editorial note — Chapter XII
Reading edition
[Footnote 18: Whilst the vegetation of the Coal-period was mainly a terrestrial one, aquatic plants are not unknown. Sea-weeds (such as the Spirophyton cauda-Galli) are common in some of the marine strata; whilst coal, according to the researches of the Abbé Castracane, is asserted commonly to contain the siliceous envelopes of Diatoms.]