Lign. 66. Fossil Fresh-water Plants.
Eocene, Paris.
| Fig. | 1.— | Seed-vessel of Chara helicteres × 10; side view. 1a.—View of the base of the same. 1b.—One of the spiral valves separated. 1c.—View from above. |
| 2.— | Seed-vessel of Chara medicaginula × 10. The upper figure is a side view: the lower, a view of the base. | |
| 3.— | Carpolithes ovulum, magnified side view. 3a.—The same, natural size. 3b.—Magnified view of the base of the same. | |
| 4.— | A piece of fresh-water limestone, with impressions of two stems of Nymphea arethusa ×. |
The Purbeck beds at Durlstone Bay, near Swanage, also contain numerous Gyrogonites associated with fresh-water shells. The bands of siliceous sinter, which occur in the lowermost deposits, are especially rich in these remains.[172]
[172] I am indebted to the Rev. Osmond Fisher, of Dorchester, for a fine suite of these and other interesting fossils from the Purbeck beds of Ridgway and Osmington, near Weymouth; and to William Shipp, Esq., of Blandford, and Edward Woodhouse, Esq., of Ansty, for many specimens from Durlstone Bay, and Ridgway.
Fossil Nympheæ. [Lign. 66, fig. 4.]—Those magnificent aquatic plants, the Water-Lilies (Nympheæ), that adorn our rivers and lakes with flowers and foliage which partake more of the characters of an exotic flora than any other of our indigenous plants, are also found fossil in the lacustrine marls and limestones of the tertiary formations of France; but the nature of these remains could only be recognized by a profound botanist, for they consist of impressions of the internal structure of the stems, which, however, is so peculiar, that no reasonable doubt of their origin can be entertained. Two imprints on a piece of limestone from Lonjumeau, presented to me by the late M. Alex. Brongniart, are figured in [Lign. 66, fig. 4]; some minute seed-vessels ([Lign. 66, fig. 3]), found with them, closely resemble those of Nympheæ, and are supposed to belong to the same plants (Class. Vég. Foss. p. 72).
Fossil Flowers.—The tertiary limestones of Monte Bolca (Wond. p. 565), so rich in ichthyolites, and other fossil remains of great interest, contain leaves, and even flowers, of liliaceous plants. The specimen figured ([Lign. 67, fig. 3]) is in the Museum at Paris, and described by M. Brongniart under the name of Antholithes (stone-flower) liliaceus; it consists of the corolla and calyx: the anthers and pistils have not been observed in any example. The discovery of this fossil should excite the young collector to search diligently for such objects in the tertiary strata of England.
FOSSIL ANGIOSPERMS.
Fossil Angiosperms.—The fossil remains of the class which constitutes the grand features of the existing floras of most countries, the Exogenous Angiosperms, are now to be considered; and though our survey of fossil botany has partaken but little of a geological arrangement, yet the reader may have observed, that a large proportion of the vegetables composing the floras of the ancient secondary formations, belonged to the Cryptogamous and Gymnospermous classes. A striking contrast is presented in the geological position of the mineralized dicotyledonous plants, of existing genera. These abound in the tertiary strata, and generally in an inverse ratio to the antiquity of the deposit, while their remains are almost wholly absent in the older rocks; neither have there been discovered in the Tertiary, any beds of vascular cryptogamia, at all approaching the immense accumulations in the Carboniferous formations.