Figs. 6, 7, & 8. Specimens of a seed-vessel, or nut, of an unknown plant, often found in the strata of the coal measures. It is called _Trigonocarpum olivæforme_, from its general shape. From Leicestershire; it probably belongs to a plant of the Palm family. [Illustration: Plate VIII.] PLATE VIII. Petrified Stems and Woods. Figs. 1-7, represent different sections and parts of some remarkably beautiful and interesting silicified stems of an extinct tribe of plants, related to the arborescent ferns, and which are found in considerable abundance at Chemnitz, near Hillersdorf, in Saxony. The name of _Psaronius_ is given to the genus by M. Cotta. Figs. 1, 2, 5, 7, are _P. helmintholithes_; figs. 3, 6, _P. asterolithes_; figs. 5, 6, 7, are enlarged figures of the transverse sections of some of the vessels forming the vascular tissue. From the stellular figure produced by transverse sections of the vessels, this fossil wood has received the name of "_Staarenstein_," or Starry-stone. In the time of Mr. Parkinson, the tubes now known to be the vessels of the vascular tissue, were supposed to have been produced by some boring or parasitical animals. Fig. 4. Transverse section of a stem of calcareous wood from the Bath oolite. Figs. 8, & 9. Calcareous fossil wood; the cylindrical cavities have been formed by the depredations of the ligniverous boring mollusk, the _Teredo_, and are now filled with translucent calcareous spar. This kind of fossil was called "_Lapis syringoides_" by the early collectors. Fig. 10. Silicified wood; the perforations are supposed to have been occasioned by the depredations of boring mollusca: the cavities are filled with a white pellucid chalcedony. [Illustration: Plate IX.] PLATE IX. Fossil Stems and Seed-vessels. Fig. 1. The strobilus or cone of an extinct family of plants whose remains are very abundant in the coal strata, and which have largely contributed to the formation of the mineral fuel now become so indispensable to the necessities and luxuries of man. There are several kinds, and although there can be no doubt that they are the seed-vessels of the _Lepidodendra_ with which they are associated, yet but few species are identified with their parent trees. The specimen figured is the _Lepidostrobus ornatus_ of Lindley and Hutton. From the coal measures of Coalbrook Dale. Fig. 2. One of the so-called "Petrified Melons" of Mount Carmel. Figs. 3 & 4. An unknown fossil body; possibly a coral.