ts_. In the marine strata which
form the base of the Carboniferous series these creatures have only
been recognised by their curious hand-shaped footprints, similar
in character to those which occur in the Triassic rocks, and which
will be subsequently spoken of under the name of _Cheirotherium_.
In the Coal-measures of Britain, the continent of Europe, and
North America, however, many bones of these animals have
been found, and we are now tolerably well acquainted with a
considerable number of forms. All of them seem to have
belonged to the division of Amphibians in which the long tail
of the young is permanently retained; and there is evidence
that some of them kept the gills also throughout life. The skull
is of the characteristic Amphibian type (fig. 132, a), with
two occipital condyles, and having its surface singularly pitted
and sculptured; and the vertebrae are hollowed out at both
ends. The lower surface of the body was defended by an armour
of singular integumentary shields or scales (fig. 132, c);
and an extremely characteristic feature (from which the entire
group derives its name) is, that the walls of the teeth are deeply
folded, so as to give rise to an extraordinary "labyrinthine"
pattern when they are cut across (fig. 132, b). Many of the
Carboniferous Labyrinthodonts are of no great size, some of
them very small, but others attain comparatively gigantic
dimensions, though all fall short in this respect of the huge
examples of this group which occur in the Trias. One of the
largest, and at the same time most characteristic, forms of the
Carboniferous series, is the genus _Anthracosaurus_, the
skull of which is here figured.

No remains of true Reptiles, Birds, or Quadrupeds have as yet
been certainly detected in the Carboniferous deposits in any part
of the world. It should, however, be mentioned, that Professor
Marsh, one of the highest authorities on the subject, has described
from the Coal-formation of Nova Scotia certain vertebrae which
he believes to have belonged to a marine reptile (_Eosaurus
Acadianus_), allied to the great _Ichthyosauri_ of the Lias. Up to
this time no confirmation of this determination has been obtained
by the discovery of other and more unquestionable remains, and
it therefore remains doubtful whether these bones of _Eosaurus_
may not really belong to large Labyrinthodonts.

LITERATURE.

The following list contains some of the more important of the
original sources o