Coal is forming now, I doubt not, in many places on the earth, and would form in many more, if man did not interfere with the processes of wild nature, by draining the fens, and embanking the rivers.

But in these islands there are two noble species, at least, which are true swamp-ferns; the Lastraea Thelypteris, which of old filled the fens, but is now all but extinct; and the Osmunda, or King-fern, which, as all know, will grow wherever it is damp enough about the roots.

Less nimbly now through brakes they wind, And ford wild creeks where men have drowned; They skirt the pool, a void the fen, And so till night, when down they lie, They steeds still saddled, in wooded ground: Rein in hand they slumber then, Dreaming of Mosby's cedarn den.