Turning the sea-wall and crossing a bit of shingle on the right, we
stand upon the western extremity of the beach.

At our feet, a smooth, globular object, of the size of a crab-apple,
is lying half-buried in the sand. Taking it in your hand, you find it
to be a univalve shell, the inhabitant of which is concealed behind a
closely-fitting door, resembling a flake of undissolved glue.

It is a Natica. Place it gently in this pool and watch for a few
moments. Slowly and cautiously the horny operculum is pushed out,
turned back, and hidden beneath a thick fleshy mantle, which spreads
over half the shell. Two long tentacles appear upon its front, like
the horns of an ox, and it begins to glide along upon its one huge
foot.

Had you seen it thus at first, you could not have believed it possible
for so bulky a body to be retracted into so small a shell. Lift it
into the air, and a stream of water pours forth as it contracts.

Two kinds are common here, one of which has a more conical spire than
the other. The animals differ somewhat in other points, but both have
a cream-colored base, and a mantle of pale cream clouded with purple.
You may get them from half an inch to three inches in diameter. Take
them home and domesticate them, and you will see surprising things.

I kept one of middling size for many months. During two or three weeks
I wondered how he lived, for he was never seen to eat. He used to
climb to the top of the tank and slide down the slippery glass as
though it were a _montagne russe_. Then he would wander about upon the