swarm, on the dry sandy shores of the
streams, they frequently compel the natives to desert their villages.
Mrs Agassiz mentions having on one occasion hung some towels to dry on
the cord of her hammock, and was about to remove them, when suddenly her
hand and arm seemed plunged into fire. She dropped the towels as if
they were hot coals, which for the moment they literally seemed to be.
She then saw that her arm was covered with little brown ants. A native
brushed them off in all haste; and an army of them was found passing
over the hammock, and out of the window, near which it hung. He said
they were on their way somewhere, and if left undisturbed would be gone
in an hour or so.

INSECTS--FIRE-FLIES.

Of those diamonds of the night, the fire-flies and fire-beetles, there
are numerous species. One of the most abundant--and of much larger
dimensions than the rest of the elaters or beetles--pyrophorus
noctilucus, called by the natives cocuja, displays both red and green
light. On the upper surface of the thorax there are two oval tubercles,
hard and transparent, like bull's-eye lights let into a ship's deck.
These are windows out of which shine a vivid green luminousness, which
appears to fill the interior of the chest. Then on the under surface of
the body, at the base of the abdomen, there is a transverse orifice in
the shelly skin, covered with a delicate membrane, which glows with a
strong ruddy light; visible, however, only when the wing-cases are
expanded. It is about an inch and a half long, of a brown colour, and
has a strong spine situated beneath the thorax, which fits at pleasure
into a small cavity on the upper part of the abdomen. By means of this
machine it can, when placed on its back, spring up a couple of inches,
and regain its feet. When preparing to do this it moves its head and
thorax backwards, so that the pectoral spine is drawn out and rests on
the edge of the sheath. The same backward movement being continued, the
spine, by the full action of the muscles, is bent like a spring, and the
insect at this moment rests on the extremity of its head and wing cases.
The effort being suddenly relaxed, the head and thorax fly up, and in
consequence the base of the wing-cases strike the supporting surface
with such force that the insect by the reaction is jerked upward, while
the projecting points of the thorax and the sheath of the spine serve to
steady the whole body.

So brilliant is the light