dodendron are enumerated in M. Ad. Brongniart s
Catalogue of fossil plants of the coal formation.
The internal structure of theLepidodendron has
been shewn to be intermediate between Lycopo-
diaceae and Coniferæ,* and the conclusions which
Prof. Lindley draws from the intermediate condition
of this curious extinct genus of fossil plants,
are in perfect accordance with the inferences
which we have had occasion to derive from analogous
conditions in extinct genera of fossil animals.
“ To Botanists, this discovery is of very
high interest, as it proves that those systematists
are right, who contend for the possibility of certain
chasms now existing between the gradations
of organization, being caused by the extinction
of genera, or even of whole orders ; the existence
of which was necessary to complete the harmony
which it is believed originally existed
in the structure of all parts of the Vegetable
kingdom. By means of Lepidodendron, a better
passage is established from Flowering to Flowerless
Plants, than by either Equisetum or Cycas,
or any other known genus.” Lindley and H u ttons
Fossil Flora, vol. ii. page 53.
* See annual Report of the Yorkshire Phil. Society for 1832.
Witham’s Fossil Vegetables, 1833, PI. 12. 13. and Lindley and
Hutton’s Fossil Flora. PI. 98 and 99.
Sigillaria*
Besides the above plants of the Coal formation
which are connected with existing Families or
Genera, there occur many others which can be
referred to no known type in the vegetable
kingdom. We have seen that the Calamites
take their place in the existing family of Equi-
setaceae; that many fossil Ferns are referrible
to living genera of this extensive family ; and
that Lepidodendra approximate to living Lyco-
podiaceae and Coniferae. Together with these,
there occur other groups of Plants unknown in
modern vegetation, and of which the duration
seems to have been limited to the Epochs of the
Transition Period. Among the largest and tallest
of these unknown forms of Plants, we find
colossal Trunks of many species, which M. Ad.
Brongniart has designated by the name of
Sigillaria. These are dispersed throughout the
sand-stones and shales that accompany the Coal,
and can occasionally be detected in the Coal
itself, to the substance of which they have
largely contributed by their remains. They
are sometimes seen in an erect position, where
views of the strata are afforded by cliffs on the
* PI. 56, Figs. 1. 2.