shoal with even five fathoms water on
it, can be discerned at a mile distance from a ship's mast-head, in
consequence of its greenish hue contrasting with the blue of deep
water. In seven fathoms water, the bottom can still be discerned on
looking over the side of a boat, especially if it have patches of
light-coloured sand; but in ten fathoms the depth of colour can
scarcely be distinguished from the dark azure of the unfathomable
ocean. This bed of reefs stretches along the coast of Australia, and
across Torres Strait, nearly to the coast of New Guinea, a distance of
one thousand miles!

One of the charms of Natural History is, that it gives a perpetual
interest to Nature,--that things, to the common eye of no attraction,
have the power of giving singular gratification; and that, in fact,
the intelligent naturalist is indulged with a sense of beauty, and an
accession of knowledge in almost every production of nature. We cannot
avoid quoting the example in the writer's own words. The subject was a
block of coral, accidentally brought up by a fish-hook from the bottom
of one of the anchorages. Nothing could have been less promising, and
any one but a naturalist would have pronounced it to be nothing but a
piece of rock, and have flung it into the sea again. But what a source
of interest does it become in the hands of the man of science.

"It was a mere worn dead fragment, but its surface was covered with
brown, crimson, and yellow _Nulliporae_, many small _Actinae_, and soft
branching _Corallines_, _Flustra_, and _Eschara_, and delicate
_Reteporae_, looking like beautiful lace-work carved in ivory. There
were several small sponges and _Alcyonia_, seaweeds of two or three
species, two species of _Comatula_, and one of _Aphiura_, of the most
vivid colours and markings, and many small, flat, round corals,
something like _Nummulites_ in external appearance.

"On breaking into the block, boring shells of several species pierced
it in all directions, many still containing their inhabitants; while
two or three _Nereis_ lay twisted in and out among its hollows and
recesses, in which, likewise, were three small species of crabs."

If it should be supposed that the receptacle or _nidus_ of all those
curious and varied things was a huge mass of rock, we are informed
that,--

"The block was not above a foot in diameter, and was a perfect
museum in itself, while its outside glared with colour, from the
many brightl