of lime. In the
ancient seas, starfishes were rare and sea urchins did not exist, but
all over the sea bottom grew creatures called crinoids, the soft parts
of which were enclosed in limy protective cases and attached to rocks on
the sea bottom by means of jointed stems. No fossils are more plentiful
in the early limestones than these wonderful "stone lilies." Indeed, the
crinoidal limestone seemed to be built of the skeletons of these
animals. The lily-like body was flung open, as a lily opens its calyx,
when the creature was feeding. But any alarm caused the tentacles to be
drawn in, and the petal-like divisions of the body wall to close tightly
together, till that wall looked like an unopened bud.

On the bottom of the Atlantic, near the Bahama Islands, these stone
lilies are still found growing. Their jointed stems and body parts are
as graceful in form and motion as any lily. The creature's mouth is in
the centre of the flower-like top, and it feeds like the sea urchin, on
particles obtained in the sea water.

The old limestones contain great quantities of "lamp shells," which are
old-fashioned bivalves. Their shells remind us of our bivalve clams and
scallops, but the internal parts were very different. The gills of clams
and oysters are soft parts. Inside of the lamp shells are coiled, bony
arms, supporting the fringed gills.

It is fortunate for us that a few lamp shells still live in the seas. By
studying the soft parts of these living remnants of a very old race we
can know the secrets of the lives of those ancient lamp shells, the
soft parts of which were all washed away, and the fossil shells of which
are preserved. Gradually the lamp shells died out, and the modern
bivalves have come to take their places. Just so, the ancient crinoids
are now almost extinct; the sea urchins and the starfishes have
succeeded them.

The chambered nautilus has its shell divided by partitions and it lives
in the outer chamber, a many-tentacled creature, that is a close
relative of the soft-bodied squid. In the ancient seas the same family
was represented by huge creatures the shells of which were chambered,
but not coiled. Their abundance and great size are proved by the rocks
in which their fossils are preserved. Some of them must have been the
rulers of the sea, as sharks and whales are to-day. Fossil specimens
have been found more than fifteen feet long and ten inches in diameter
in the ancient rocks of some of the West