The different varieties of the scallop do not
possess the power of burrowing; they inhabit
deep water, where they lie on a rocky or shelly
bottom, and swim, or rather fly, through the
sea by the muscular action of suddenly opening
and shutting their shells, one of which is
flat and the other concave. During the season
any fishmonger's shop in London will enable us
to study its peculiar characteristics, and the
margin of its mantle will be found furnished
with glands similar to those of the cockle, but
on a larger scale, which secrete carbonate of
lime, and from this substance, derived from the
fish itself, the shell is gradually formed. The
shell grows by constant additions to its margin,
and as it increases, its walls thicken, while the
outer edges appear to shelve, becoming thinner;
but the observer is struck by the admirable
order in which the component parts are
arranged.

The oyster prefers mixed sandy and stony
ground, and the fishermen assert that the fish,
lying in its bed in the sea, may be seen to close
its shell when the shadow of a boat passes over it.
Here among the shingles washed by the tide, is
an oyster-shell in a spot where it would seem
improbable that the fish was ever invaded by
an oyster-knife. When we consider how difficult
it is at times to open an oyster, how
resolutely the strong-built dwelling he has formed
for himself resists the invader, we fancy that he
cannot be readily disturbed when at rest in the
sea. But this shell teaches us that the oyster
has secret enemies who bore through his shell.
Amongst the most numerous, the most
formidable, and the most untiring, are small sea-
worms, which attack him at all points in his
tenement. He first meets their attempts by
depositions of pearly matter interposed between
his soft and delicate skin and their voracious
mouths, but having once settled in his shell,
he is helpless and cannot remove them, and
as they renew their efforts he is often
exhausted. In the wounds they pierce, a species
of sponge constantly fixes itself, which spreads
like the dry-rot fungus in the timber of our
dwellings and ships, and thus under the persecution
of accumulated enemies the oyster perishes,
leaving his shell to the mercy of the waves.

As rocks intervene between the sands and the
pebbly beach, let us pause and examine the
peculiar shell-fishes which attach themselves to
their surface. Here are clusters of blue
mussels, which, though possessing bivalve shells, are
destined to a stationary existence on the naked
rock exposed to the sea. Nature has enabled
them to anchor themselves as firmly and as
securely as a ship in harbour. The foot is too
small for the purpose of progression, it is therefore
used in weaving silken threads or tendrils
of great strength, by which the animal affixes
itself to the rock and also to its neighbours
of the same family. See! we have here a
community of mussels, grasping each other as well
as the rock, and in safety defying the storm.
Observe, also, another class, the limpet, known
as the genus Patellidæ, from its obvious
resemblance to the knee-pan—patella. How flat it lies,
and how firmly the shell, a flat disc, adheres to
the smooth stone! The tongue of the limpet
is a remarkable piece of mechanism, contrived
so as to exhaust the air, and, by creating a
vacuum beneath the external pressure of the
air, enables the limpet to cling to the rock: thus
furnishing to modern art a model of the
pneumatic bracket in common use made of india-
rubber. The very seaweeds that seem so worthless
on the rocks must not be passed without
notice. The sea-wrack is the most common;
some of the varieties swell at irregular intervals
into oval air-cells, generally arranged in pairs;
those of the knotted wrack are too tough to be
burst by the pressure of the fingers, but by
stamping on them or throwing them into the
fire they produce a report similar to the explosive
detonating balls in which boys take delight.
This long thin seaweed, called by several names,
sea-lace, sea-catgut, sea-whipcord or whiplash,
grows in the sea several fathoms deep, attached
to stones at the bottom, and, reaching the surface
—perhaps attracted by the light—is sometimes
found forty feet long. The tube is divided into
chambers, the cavities being filled with air,
probably generated by the plant itself, and it is
supposed that the air-cells are intended to enable
the plant to float upon the ocean. We have
also here the sea network, which is very common,
and is remarkable for its regular reticulated
texture. Let us gather some of the delicate
weed, covering portions of the rock, of a deep
green colour, but finer than the finest silk.
From this is made the epicure's dish brought in
quantity from Devonshire, and sold as a delicacy
under the name of laver, which is said to be a
corruption of lava, from its supposed
resemblance to that substance when liquid. There
is a sea-plant of singular beauty representing
in shape a peacock's tail, which grows attached
to the rocks at the bottom of still and generally
shallow marine pools. It rises in the form of a
fan of a yellowish olive hue, marked with
concentric zones or bands of a dark brown. The
outward edge is constantly seen fringed by
exceedingly minute filaments which, while the
plant is living, often reflect the iridescent colours
or tints of the prism and rainbow. From the
coarsest of these weeds—the sea-wrack—when
burned, is procured kelp, or barilla, an essential
ingredient in the manufacture of soap and glass.
By chemical treatment we derive from barilla
the remarkable product known as iodine, which,
in its native state, is supposed to float in minute
particles in sea air and to conduce materially to
health; it is also believed that the efficacy of
many mineral springs is owing to its presence,
and it is said to be in some measure an antidote
to strychnine.

We are now upon the strand or sea-beach,
which probably once formed part of the seabed,
and is composed of mixed gravelly, sandy,
and shelly deposits, in which we constantly find
organic remains. Observe

                           ——the murmuring surge

That on the unnumbered pebbles idly chafes.