hich fringes their
jaws. Here are drawings of them. 1. Limacina (on which the whales
feed); and 2. Hyalea, a lovely little thing in a glass shell, which lives
in the Mediterranean.

But since then strange discoveries have been made, especially by the
naval officers who surveyed the bottom of the great Atlantic Ocean before
laying down the electric cable between Ireland and America. And this is
what they found:

That at the bottom of the Atlantic were vast plains of soft mud, in some
places 2500 fathoms (15,000 feet) deep; that is, as deep as the Alps are
high. And more: they found out, to their surprise, that the oozy mud of
the Atlantic floor was made up almost entirely of just the same atomies
as make up our chalk, especially globigerinas; that, in fact, a vast bed
of chalk was now forming at the bottom of the Atlantic, with living
shells and sea-animals of the most brilliant colours crawling about on it
in black darkness, and beds of sponges growing out of it, just as the
sponges grew at the bottom of the old chalk ocean, and were all,
generation after generation, turned into flints.

And, for reasons which you will hardly understand, men are beginning now
to believe that the chalk has never ceased to be made, somewhere or
other, for many thousand years, ever since the Winchester Downs were at
the bottom of the sea: and that "the Globigerina-mud is not merely _a_
chalk formation, but a continuation of _the_ chalk formation, so _that we
may be said to be still living in the age of Chalk_." {1} Ah, my little
man, what would I not give to see you, before I die, add one such thought
as that to the sum of human knowledge!

So there the little creatures have been lying, making chalk out of the
lime in the sea-water, layer over layer, the young over the old, the dead
over the living, year after year, age after age--for how long?

Who can tell? How deep the layer of new chalk at the bottom of the
Atlantic is, we can never know. But the layer of live atomies on it is
not an inch thick, probably not a tenth of an inch. And if it grew a
tenth of an inch a year, or even a whole inch, how many years must it
have taken to make the chalk of our downs, which is in some parts 1300
feet thick? How many inches are there in 1300 feet? Do that sum, and
judge for yourself.

One difference will be found between the chalk now forming at the bottom
of the ocean, if it ever become dry land, and the chalk on which you
tread on