"first-created forms of living beings," as if they were the most
familiar things in the world; and even cautious writers seem to be on
quite friendly terms with the "archetype" whereby the Creator was
guided "amidst the crash of falling worlds." Just as it used to be
imagined that the ancient world was physically opposed to the present,
so it is still widely assumed that the living population of our globe,
whether animal or vegetable, in the older epochs, exhibited forms so
strikingly contrasted with those which we see around us, that there is
hardly anything in common between the two. It is constantly tacitly
assumed that we have before us all the forms of life which have ever
existed; and though the progress of knowledge, yearly and almost
monthly, drives the defenders of that position from their ground, they
entrench themselves in the new line of defences as if nothing had
happened, and proclaim that the 'new' beginning is the 'real'
beginning.

Without for an instant denying or endeavouring to soften down the
considerable positive differences (the negative ones are met by another
line of argument) which undoubtedly obtain between the ancient and the
modern worlds of life, we believe they have been vastly overstated and
exaggerated, and this belief is based upon certain facts whose value
does not seem to have been fully appreciated, though they have long
been more or less completely known.

The multitudinous kinds of animals and plants, both recent and fossil,
are, as is well known, arranged by zoologists and botanists, in
accordance with their natural relations, into groups which receive the
names of sub-kingdoms, classes, orders, families, genera and species.
Now it is a most remarkable circumstance that, viewed on the great
scale, living beings have differed so little throughout all geologic