ies were known to Adolphe Brongniart as early as 1849,
and that number has largely increased since.

Now one point is specially noticeable about these plants of the coal;
namely, that they may at least have grown in swamps.

First, you will be interested if you study the coal flora, with the
abundance, beauty, and variety of the ferns. Now ferns in these
islands grow principally in rocky woods, because there, beside the
moisture, they get from decaying vegetable or decaying rock,
especially limestone, the carbonic acid which is their special food,
and which they do not get on our dry pastures, and still less in our
cultivated fields. 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. In Hampshire, in Devon, and Cornwall, and in
the southwest of Ireland, the King-fern too is a true swamp fern.
But in the Tropics I have seen more than once noble tree-ferns
growing in wet savannahs at the sea-level, as freely as in the
mountain-woods; ferns with such a stem as some of the coal ferns had,
some fifteen feet in height, under which, as one rode on horseback,
one saw the blazing blue sky, as through a parasol of delicate lace,
as men might have long ages since have seen it, through the plumed
fronds of the ferns now buried in the coal, had there only been a man
then created to enjoy its beauty.

Next we find plants called by geologists Calamites. There is no
doubt now that they are of the same family as our Equiseta, or horse-
tails, a race which has, over most parts of the globe, dwindled down
now from twenty or thirty feet in height, as they were in the old
coal measures, to paltry little weeds. The tallest Equisetum in
England--the beautiful E. Telmateia--is seldom five feet high. But
they, too, are mostly mud and swamp plants; and so may the Calamites
have been.

The Lepidodendrons, again, are without doubt the splendid old
representatives of a family now dwindled down to such creeping things
as our club-mosses, or Lycopodiums. Now it is a certain fact, which
can be proved by the microscope, that a very great part of the best
coal is actually made up of millions of the minute seeds of club-
mosses, such as grow--a few of them, and those very small--on our
mo