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
moors; a proof, surely, not only of the vast amount of the vegetation
in the coal-making age, but also of the vast time during which it
lasted. The Lepidodendra may have been fifty or sixty feet high.
There is not a Lycopodium in the world now, I believe, five feet
high. But the club-mosses are now, in these islands and elsewhere,
lovers of wet and peaty soils, and so may their huger prototypes have
been, in the old forests of the coal.
Of the Sigillariae we cannot say as much with certainty, for
botanists are not agreed as to what low order of flowerless plants
they belong. But that they rooted in clay beds there is proof, as
you will hear presently.
And as to the Conifers, or pine-like trees--the Dadoxylon, of which
the pith goes by the name of Sternbergia, and the uncertain tree
which furnishes in some coal-measures bushels of a seed connected
with that of the yew--we may suppose that they would find no more
difficulty in growing in swamps than the cypress, which forms so
large a portion of the vegetation in the swamps of the Southern
United States.
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