with well-ossified vertebrae, in
the Edinburgh coal-field. Since that time eight or ten distinct genera
of Labyrinthodonts have been discovered in the Carboniferous rocks
of England, Scotland, and Ireland, not to mention the American forms
described by Principal Dawson and Professor Cope. So that, at the
present time, the Labyrinthodont Fauna of the Carboniferous rocks is
more extensive and diversified than that of the Trias, while its chief
types, so far as osteology enables us to judge, are quite as highly
organized. Thus it is certain that a comparatively highly organized
vertebrate type, such as that of the Labyrinthodonts, is capable
of persisting, with no considerable change, through the period
represented by the vast deposits which constitute the Carboniferous,
the Permian, and the Triassic formations.

The very remarkable results which have been brought to light by the
sounding and dredging operations, which have been carried on with
such remarkable success by the expeditions sent out by our own, the
American, and the Swedish Governments, under the supervision of
able naturalists, have a bearing in the same direction. These
investigations have demonstrated the existence, at great depths in the
ocean, of living animals in some cases identical with, in others very
similar to, those which are found fossilized in the white chalk. The
_Globigerinae_, Cyatholiths, Coccospheres, Discoliths in the one are
absolutely identical with those in the other; there are identical, or
closely analogous, species of Sponges, Echinoderms, and Brachiopods.
Off the coast of Portugal, there now lives a species of _Beryx_,
which, doubtless, leaves its bones and scales here and there in the
Atlantic ooze, as its predecessor left its spoils in the mud of the
sea of the Cretaceous epoch.

Many years ago[1] I ventured to speak of the Atlantic mud as "modern
chalk," and I know of no fact inconsistent with the view which
Professor Wyville Thomson has advocated, that the modern chalk is not
only the lineal descendant of the ancient chalk, but that it remains,
so to speak, in the possession of the ancestral estate; and that from
the Cretaceous period (if not much earlier) to the present day, the
deep sea has covered a large part of what is now the area of the
Atlantic. But if _Globigerinae_, and _Terebratula caput-serpentis_
and _Beryx_, not to mention other forms of animals and of plants, thus
bridge over the interval between the present and