the
modern club-moss furnishes a complete explanation of the fossil
remains of the _Lepidodendra_, and the fronds of some of the ancient
ferns are hard to distinguish from existing ones. At the same time,
it must be remembered, that there is nowhere in the world, at present,
any _forest_ which bears more than a rough analogy with a coal-forest.
The types may remain, but the details of their form, their relative
proportions, their associates, are all altered. And the tree-fern
forest of Tasmania, or New Zealand, gives one only a faint and remote
image of the vegetation of the ancient world.

Once more, an invariably-recurring lesson of geological history,
at whatever point its study is taken up: the lesson of the almost
infinite slowness of the modification of living forms. The lines of
the pedigrees of living things break off almost before they begin to
converge.

Finally, yet another curious consideration. Let us suppose that one of
the stupid, salamander-like Labyrinthodonts, which pottered, with
much belly and little leg, like Falstaff in his old age, among the
coal-forests, could have had thinking power enough in his small brain
to reflect upon the showers of spores which kept on falling through
years and centuries, while perhaps not one in ten million fulfilled
its apparent purpose, and reproduced the organism which gave it birth:
surely he might have been excused for moralizing upon the thoughtless
and wanton extravagance which Nature displayed in her operations.

But we have the advantage over our shovel-headed predecessor--or
possibly ancestor--and can perceive that a certain vein of thrift runs
through this apparent prodigality. Nature is never in a hurry, and
seems to have had always before her eyes the adage, "Keep a thing long
enough, and you will find a use for it." She has kept her beds of coal
many millions of years without being able to find much use for them;
she has sent them down beneath the sea, and the sea-beasts could make
nothing of them; she has raised them up into dry land, and laid the
black veins bare, and still, for ages and ages, there was no living
thing on the face of the earth that could see any sort of value in
them; and it was only the other day, so to speak, that she turned a
new creature out of her workshop, who by degrees acquired sufficient
wits to make a fire, and then to discover that the black rock would
burn.

I suppose that nineteen hundred years ago, when Julius Caesar w