Atlantic soundings, he found the two to be identical; and thus
proved that the chalk, like the soundings, contains these mysterious
coccoliths and coccospheres. Here was a further and a most interesting
confirmation, from internal evidence, of the essential identity of the
chalk with modern deep-sea mud. Globigerinae, coccoliths, and
coccospheres are found as the chief constituents of both, and testify
to the general similarity of the conditions under which both have been
formed.[2]

[Footnote 2: I have recently traced out the development of the
"coccoliths" from a diameter of 1/7000th of an inch up to their
largest size (which is about 1/1600th), and no longer doubt that they
are produced by independent organisms, which, like the Globigerinae,
live and die at the bottom of the sea.]

The evidence furnished by the hewing, facing, and superposition of the
stones of the Pyramids, that these structures were built by men, has
no greater weight than the evidence that the chalk was built by
Globigerinae; and the belief that those ancient pyramid-builders were
terrestrial and air-breathing creatures like ourselves, is not better
based than the conviction that the chalk-makers lived in the sea.

But as our belief in the building of the Pyramids by men is not only
grounded on the internal evidence afforded by these structures, but
gathers strength from multitudinous collateral proofs, and is clinched
by the total absence of any reason for a contrary belief; so the
evidence drawn from the Globigerinae that the chalk is an ancient
sea-bottom, is fortified by innumerable independent lines of evidence;
and our belief in the truth of the conclusion to which all positive
testimony tends, receives the like negative justification from the
fact that no other hypothesis has a shadow of foundation.

It may be worth while briefly to consider a few of these collateral
proofs that the chalk was deposited at the bottom of the sea.

The great mass of the chalk is composed, as we have seen, of the
skeletons of Globigerinae, and other simple organisms, imbedded in
granular matter. Here and there, however, this hardened mud of the
ancient sea reveals the remains of higher animals which have lived and
died, and left their hard parts in the mud, just as the oysters die
and leave their shells behind them, in the mud of the present seas.

[Illustration: UPPER SILURIAN CORALS AND CRUSTACEANS.]

There are, at the present day, certain groups of a