We find the following quote from a Book titled:  More Letters of Charles Darwin Vol. 2
Down, May 22nd, 1860.

"Lyell tells me that Binney has published in Proceedings of Manchester
Society a paper trying to show that Coal plants must have grown in very
marine marshes.  (555/1.  "On the Origin of Coal," by E.W. Binney, "Mem.
Lit. Phil. Soc. Manchester," Volume VIII., 1848, page 148.  Binney examines
the evidence on which dry land has been inferred to exist during the
formation of the Coal Measures, and comes to the conclusion that the land
was covered by water, confirming Brongniart's opinion that Sigillaria was
an aquatic plant.
  He believes the Sigillaria 'grew in water, on the
deposits where it is now discovered, and that it is the plant which in a
great measure contributed to the formation of our valuable beds of coal.'
(Loc. cit., page 193.))  Do you remember how savage you were long years ago
at my broaching such a conjecture?"
  Emphasis Added