[5] Acadian Geology, 2nd edit., 1868.
[6] Quart. Geol. Journ., vol. ix, p. 58.
[7] Dawson, Air-Breathers of the Coal in Nova Scotia, Montreal, 1863.
[8] Dawson, Acadian Geology, 1868, p. 385.
CHAPTER XXIV.
FLORA AND FAUNA OF THE CARBONIFEROUS PERIOD.
Vegetation of the Coal Period. — Ferns, Lycopodiaceæ, Equisetaceæ, Sigillariæ, Stigmariæ, Coniferæ. — Angiosperms. — Climate of the Coal Period. — Mountain Limestone. — Marine Fauna of the Carboniferous Period. — Corals. — Bryozoa, Crinoidea. — Mollusca. — Great Number of fossil Fish. — Foraminifera.
Vegetation of the Coal Period.—In the last chapter we have seen that the seams of coal, whether bituminous or anthracitic, are derived from the same species of plants, and Goppert has ascertained that the remains of every family of plants scattered through the shales and sandstones of the coal-measures are sometimes met with in the pure coal itself—a fact which adds greatly to the geological interest of this flora.
The coal-period was called by Adolphe Brongniart the age of Acrogens,[[1]] so great appears to have been the numerical preponderance of flowerless or cryptogamic plants of the families of ferns, club-mosses, and horse-tails. He reckoned the known species in 1849 at 500, and the number has been largely increased by recent research in spite of reductions owing to the discovery that different parts of even the same plants had been taken for distinct species. Notwithstanding these changes, Brongniart’s generalisation concerning this flora still holds true, namely, that the state of the vegetable world was then extremely different from that now prevailing, not only because the cryptogamous plants constituted nearly the whole flora, but also because they were, on the whole, more highly developed than any belonging to the same class now existing, and united some forms of structure now only found separately and in distinct orders. The only phænogamous plants were constitute any feature in the coal are the coniferæ; monocotyledonous angiosperms appear to have been very rare, and the dicotyledonous, with one or two doubtful exceptions, were wanting. For this we are in some measure prepared by what we have seen of the Secondary or Mesozoic floras if, consistently with the belief in the theory of evolution, we expect to find the prevalence of simpler and less specialised organisms in older rocks.
Ferns.—We are struck at the first glance with the similarity of the ferns to those now living. In the fossil genus Pecopteris, for example (Fig. 448), it is not easy to decide whether the fossils might not be referred to the same genera as those established for living ferns; whereas, in regard to some of the other contemporary families of plants, with the exception of the fir tribe, it is not easy to guess even the class to which they belong. The ferns of the Carboniferous period are generally without organs of fructification, but in the few instances in which these do occur in a fit state for microscopical investigations they agree with those of the living ferns.
