the idea that, in vegetable, as well as animal creation, a progress
has been observed, in conformity with advancing conditions. It is
also curious to find a missing link of so much importance in a genus
of plants which has long ceased to have a living place upon earth.

The other leading plants of the coal era are without representatives
on the present surface, and their characters are in general less
clearly ascertained. Amongst the most remarkable are--the
sigillaria, of which large stems are very abundant, shewing that the
interior has been soft, and the exterior fluted with separate leaves
inserted in vertical rows along the flutings--and the stigmaria,
plants apparently calculated to flourish in marshes or pools, having
a short, thick, fleshy stem, with a dome-shaped top, from which
sprung branches of from twenty to thirty feet long. Amongst
monocotyledons were some palms, (flabellaria and naeggerathia,)
besides a few not distinctly assignable to any class.

The dicotyledons of the coal are comparatively few, though on the
present surface they are the most numerous sub-class. Besides some
of doubtful affinity, (annularia, asterophyllites, &c.,) there were a
few of the pine family, which seem to have been the highest class of
trees of this era, and are only as yet found in isolated cases, and
in sandstone beds. The first discovered lay in the Craigleith
quarry, near Edinburgh, and consisted of a stem about two feet thick,
and forty-seven feet in length. Others have since been found, both
in the same situation, and at Newcastle. Leaves and fruit being
wanting, an ingenious mode of detecting the nature of these trees was
hit upon by Mr. Witham of Lartington. Taking thin polished cross
slices of the stem, and subjecting them to the microscope, he
detected the structure of the wood to be that of a cone-bearing tree,