Part 16

15. The reign of Angiosperms includes the Cretaceous and Tertiary periods, and is marked by the predominance of Angiospermous Dicotyledons.

16. Coal is a vague term, referring to all kinds of fuel formed from the chemically-altered remains of plants.

17. When there is a great admixture of mineral matter, so that it will not burn as fuel, then a shale is produced.

18. The microscopic structure of Coal probably varies according to the nature of the plants of which it is composed, and the changes produced by pressure, heat, and other causes. Cellular tissue, punctated woody tissue, and scalariform vessels, have been detected in it.

19. Certain temporary and local floras seem to have given origin to peculiar layers of coal.

20. During the Carboniferous epoch we meet with Ferns, Sigillarias, and their roots called Stigmarias, Lepidodendrons, Ulodendrons, Calamites, Gymnosperms, etc.

21. The plants forming coal have grown in the basin where the coal is found; but sandstone rocks in the coal-measures deposited by water having a considerable velocity, and consequently carrying power, contain sometimes trunks of large trees which have been drifted like snags.

22. The strata between the Permian epoch and Chalk display numerous Gymnosperms, especially belonging to the Cycadaceous Order. Some of them exhibit limited coal deposits.

23. The Chalk and Tertiary strata display not only Acrogens and Gymnosperms, but also Angiospermous Dicotyledons, some of which, at the Miocene period, belong apparently to genera of the present day.

24. Brown Coal occurs in the Upper Tertiary beds, and in it vegetable structure is easily seen under the microscope.

25. Raulin thinks that during the Tertiary epoch the flora of Europe has gradually assumed a more temperate character.

26. The Eocene flora, according to Unger, resembled in many respects that of Australia at the present day.

27. The Miocene flora is characterised by a number of exotic forms of warm regions with those of temperate climates. It is largely seen in the Arctic Regions.

28. The Pliocene flora has great analogy with that of the temperate regions of Europe, North America, and Japan.

WORKS ON FOSSIL BOTANY.

On the subject of Fossil Botany the following works may be consulted:--

Abhandlungen der Kaiserlich Königlichen Geologischen Reichsanstalt, Band. ii. Wien. 1855.

Argyll, Duke of, on Tertiary Leaf-Beds in the Isle of Mull, Journ. Geol. Soc. Lond., vii. May 1851.

Balfour, J. H., on certain Vegetable Organisms in Coal from Fordel, Trans. R.S.E., vol. xxi. p. 187.

Baily, W. H., Figures of Characteristic British Fossils, 1871-2.

Bennett, J. Hughes, on the Structure of Torbane Hill Mineral and other Coals, Trans. R. Soc. Ed., vol. xxi. p. 173.

Binney, E. W., on Calamites and Calamodendron, Palæontographical Society's Memoirs, 1868.

---- on the Structure of Fossil Plants found in the Carboniferous Strata. Palæontographical Society's Memoirs, 1871.

---- Description of some Fossil Plants, showing Structure in the Lower Coal Seam of Lancaster and Yorkshire, Phil. Trans., vol. 155, p. 579.

Bowerbank, Fossil Fruits and Seeds of the London Clay.

Brongniart, Histoire des Végétaux Fossiles, 1828-44.

---- Observations sur la Structure intérieure du Sigillaria, etc., in Archives du Museum, i. 405.

---- Exposition Chronologique des Périodes de Végétation, in Ann. des Sc. Nat. 3d series, Bot. xi. 285.