irritant fluid, generally supposed to
be formic acid, from the mouth, when alarmed, and this, if it enters the
eye, causes acute pain.

[Illustration: Fig. 4.--North American Great Peacock.]

The caterpillars of the Swallow-tailed moths, when irritated, give out
an offensive smell, but they are unable to 'spray.'

Many beetles have the power of forcing drops of blood from a minute hole
in one of the legs. This blood is saturated either with a fluid which
causes a burning sensation on everything it touches, or with an
intolerable odour; in either case the result is the same--they are given
a wide berth by all who have discovered their power. The little
lady-bird beetle, for example, sends out, when frightened, a tiny drop
of a yellow fluid from the 'knee-joint,' which has a smell like opium.
The Javanese 'violin-beetle' gives off a fluid which is said to paralyse
the fingers for twenty-four hours.

[Illustration: Fig. 5.--Caterpillar of Spurge-hawk Moth fighting
Ichneumon Fly.]

W. P. PYCRAFT, F.Z.S., A.L.S.

THE BLACK SWAN.

The Black Swan is an Australian bird, and was not known in Europe until
that continent began to be explored, although black swans had been often
spoken of before that time as a kind of fabulous monster. The ordinary
white, or mute, swan, which graces our rivers and lakes, has been
admired, and even protected by laws, for many centuries, and its plumage
is so beautifully and uniformly snowy that we can hardly be surprised if
people thought that all swans must be white, and should regard a black
swan as impossible, like the two-necked swan sometimes painted upon
inn-signs. But travellers have discovered many strange animals in
unexplored countries, and we now know that there are not only black
swans, but even swans that have a black neck and a white body.

The plumage of the black swan, with the exception of the quill
feathers, which are white, is entirely black. The bill and the skin
between the eyes are a beautiful red, which contrasts handsomely with
the black feathers. The tail of the bird is very short, and, next to the
colour of the plumage, this is the chief peculiarity which distinguishes
it from the white swan.

[Illustration: The Black Swan of Australia.]

The black swan frequents the swamps and secluded bays on the Australian
coast. It is not a very shy bird, and is frequently seen by the
sportsman and the camper-out. It enjoys the companionship of its kind,
and congreg