a brushwood fire; but although thousands are
killed, not more than 160 jars of clear oil are obtained. A small river
flows through the cavern, and the visitor is compelled, as he proceeds,
to wade through water, not, however, more than two feet deep. From the
entrance as far as 1458 feet the cavern maintains the same direction,
width, and height, after which it loses its regularity, and its walls
are covered with stalactites. The same bird has been found in the
province of Bogota, and may probably be discovered in other caverns.
Animal life exists in considerable quantities in many subterranean
regions, such as beetles, eyeless spiders, scorpions, millipedes, and
crustaceans. The most curious is the Proteus anguinus, which breathes
at the same time through lungs and gills. It has a long eel-like body,
with an elongated head, and four very short and thin legs. The skin is
flesh-coloured, and so translucent that the liver and heart, which beat
about fifty times a minute, can be seen distinctly beneath. Two little
black spots, resembling eyes, lie buried under the skin, and are only
partially developed. Weak as it appears, it glides rapidly through the
water, when its four little legs remain motionless; it uses them,
indeed, only for creeping, and then in a very imperfect manner. Seven
distinct species of proteus have been discovered, six of which were
found in the cavern of Carniola, besides crickets, spiders, and a few
crustaceae. A peculiar blind rat is found in the Mammoth Cave of
Kentucky. A blind fish swims in its rivers, and Professor Agassiz is of
opinion that they, like all other blind animals of the cavern world,
have at no time been connected with the world of light.

Vegetable life also exists in caverns, but consists of such mushrooms or
fungi which, shunning the light, love darkness and damp. For their
existence, however, moisture and warmth of air is necessary, but they
are invariably dependent on organic basis, and are commonly found
germinating on pieces of wood, particularly in a state of decomposition.
More than seventy subterranean fungi have been discovered, some
remarkable for their size. A few years ago a fungus was found growing
from the wood-work of a tunnel near Doncaster, which measured no less
than fifteen feet in diameter.

In the neighbourhood of Paris the cultivation of edible mushrooms is
extensively carried on in the catacombs or caverns, seventy or eighty
feet below the surfa