er Bank, can tell us next to
nothing about the fish, crustaceans, mollusks, and corals, which are
being buried in the Bay of Bengal. Still stronger is the argument in the
case of terrestrial life. With more numerous and greater contrasts
between the types inhabiting one continent and those inhabiting another,
there is a far more imperfect registry of them. Schouw marks out on the
Earth more than twenty botanical regions, occupied by groups of forms so
distinct, that, if fossilized, geologists would scarcely be disposed to
refer them all to the same period. Of Faunas, the Arctic differs from
the Temperate; the Temperate from the Tropical; and the South Temperate
from the North Temperate. Nay, in the South Temperate Zone itself, the
two regions of South Africa and South America are unlike in their
mammals, birds, reptiles, fishes, mollusks, insects. The shells and
bones now lying at the bottoms of lakes and estuaries in these several
regions, have certainly not that similarity which is usually looked for
in those of contemporaneous strata; and the recent forms exhumed in any
one of these regions would very untruly represent the present Flora and
Fauna of the Earth. In conformity with the current style of geological
reasoning, an exhaustive examination of deposits in the Arctic circle,
might be held to prove that though at this period there were sundry
mammals existing, there were no reptiles; while the absence of mammals
in the deposits of the Galapagos Archipelago, where there are plenty of
reptiles, might be held to prove the reverse. And at the same time, from
the formations extending for two thousand miles along the great
barrier-reef of Australia--formations in which are imbedded nothing but
corals, echinoderms, mollusks, crustaceans, and fish, along with an
occasional turtle, or bird, or cetacean--it might be inferred that there
lived in our epoch neither terrestrial reptiles, nor terrestrial
mammals. The mention of Australia, indeed, suggests an illustration
which, even alone, would amply prove our case. The Fauna of this region
differs widely from any that is found elsewhere. On land, all the
indigenous mammals, except bats, belong to the lowest, or implacental
division; and the insects are singularly different from those found
elsewhere. The surrounding seas contain numerous forms which are more or
less strange; and among the fish there exists a species of shark, which
is the only living representative of a genus t