is made a standard of comparison for all
preceding creations. Of course, the collections of living types in any
museum must be more numerous than those of fossil forms, for the simple
reason that almost the whole of the present surface of the earth, with
the animals and plants inhabiting it, is known to us, whereas the
deposits of the Silurian and Devonian periods are exposed to view only
over comparatively limited tracts and in disconnected regions. But let
us compare a given extent of Silurian or Devonian sea-shore with an
equal extent of sea-shore belonging to our own time, and we shall
soon be convinced that the one is as populous as the other. On the
New-England coast there are about one hundred and fifty different kinds
of fishes, in the Gulf of Mexico two hundred and fifty, in the Red Sea
about the same. We may allow in present times an average of two hundred
or two hundred and fifty different kinds of fishes to an extent of ocean
covering about four hundred miles. Now I have made a special study of
the Devonian rocks of Northern Europe, in the Baltic and along the shore
of the German Ocean. I have found in those deposits alone one hundred
and ten kinds of fossil fishes. To judge of the total number of species
belonging to those early ages by the number known to exist now is about
as reasonable as to infer that because Aristotle, familiar only with the
waters of Greece, recorded less than three hundred kinds of fishes in
his limited fishing-ground, therefore these were all the fishes then
living. The fishing-ground of the geologist in the Silurian and Devonian
periods is even more circumscribed than his, and belongs, besides, not
to a living, but to a dead world, far more difficult to decipher.

But the sciences of Geology and Palaeontology are making such rapid
progress, now that they go hand in hand, that our familiarity with past
creations is daily increasing. We know already that extinct animals
exist all over the world: heaped together under the snows of
Siberia,--lying thick beneath the Indian soil,--found wherever English
settlers till the ground or work the mines of Australia,--figured in the
old Encyclopaedias of China, where the Chinese philosophers have drawn
them with the accuracy of their nation,--built into the most beautiful
temples of classic lands, for even the stones of the Parthenon are full
of the fragments of these old fossils, and if any chance had directed
the attention of Aristotle towards