Fig. 3. Carbonized coniferous wood, from the so-called "Bovey Coal" formation of Devonshire. Fig, 4. A piece of calcareous wood, showing very distinctly the ligneous structure on the surface. Fig. 5. Lignite, or carbonized wood, in clay; the cracks or fissures in the wood are filled up with white calcareous spar. Specimens of this kind are common in many argillaceous strata, as well as in limestone. Fig. 6. A fragment of shale, covered with the imprints of the leaf-stalks that have been shed. It is a species of _Lepidodendron_. See description of Plate XXVI. Fig. 7. This fossil vegetable is part of the stem of a tree; and possibly of a species of _Sigillaria_. Fig. 8. Portion of a nodule of ironstone, enclosing some pinnules or leaflets of a beautiful fern (_Neuropteris_): from Coalbrook Dale, Shropshire. [Illustration: Plate II.] PLATE II. Petrified Woods. Fig. 1. Silicified bituminized wood; probably from New Holland. Fig. 2. Silicified root of a coniferous tree, (_Rhizolithes_, of the early collectors,) "resembling in structure that of the larch."--_Mr. Parkinson._ Fig. 3. A similar example of silicified bituminous wood, or root. Fig. 4. Fossil coniferous wood, a longitudinal section. Fig. 5. Another section of the same fossil wood. Fig. 6. "Petrified larch-tree," from Mount Krappe in Hungary. Fig. 7. Silicified bituminous wood. Fig. 8. "Jasperized wood, resembling in structure that of the hazel."--_Mr. Parkinson._ Fig. 9. Silicified coniferous wood; apparently a dried and withered mass, before it underwent petrifaction. Fig. 10. Silicified wood, having a cavity lined with mammillated chalcedony; appearing as if the silex had percolated through the substance of the mass, and had slowly oozed into the hollow. Fig. 11. Silicified bituminous wood. In this specimen the siliceous matter occurs in yellow semi-pellucid globules; the colour is supposed to have been derived from the bitumen. The silicified woods delineated above, belong to the division which Mr. Parkinson denominated opaline; he conceived their peculiar characters to have resulted from an infiltration of fluid silex into the ligneous tissue, which, having previously undergone bituminization, was in a permeable state; hence originated the conchoidal fracture and peculiar resinous lustre which these specimens exhibit.