M. Brongniart, who carefully examined a great number of agates and pebbles, with the view of determining if vegetable substances were ever imbedded in them, could not detect a single instance in which the apparent mosses, confervæ, or algæ, were organic; in every case the mineral origin of the pseudo-vegetation was, in his opinion, unequivocal. Some of the beautiful green arborescent bodies in quartz pebbles, even under the microscope, present so close a resemblance to confervæ and mosses, that it is difficult to persuade oneself they are not vegetable structures; but the observations of M. Brongniart appear to me conclusive as to their mineral nature.[75] With the exception of three or four species of Jungermannia, and four or five of Muscites in Amber, M. Brongniart states that he knows but one true fossil plant of the family of Mosses; the Muscites Tournalii from the fresh-water tertiary deposits of Armissan.
[75] See Histoire des Végétaux Fossiles, pp. 29-34.
Vascular, or Acrogenous Cryptogamia.—These plants, as the name implies, possess a more complicated structure than the preceding, having vascular tissue as varied as in the phanerogamia.
Equisetaceæ.—The common species of Equisetum, or Marestail, is a plant that grows in marshy tracts, and on the banks of ditches and rivers; it has a jointed stalk, garnished with elegant sheaths which embrace the stem, and verticillate linear leaves: it attains a height of two feet, and is half an inch in diameter. In the fossil state there are many plants allied to the Equisetum, but only a few that are generically the same.
Lign. 12. Equisetum Lyellii.
Wealden. Pounceford. nat.
| Fig. | 1.— | A stem, having two sheaths, and a bud at the lowermost joint. |
| 2.— | Stem of a young plant, with sheaths, preserved in pyrites. | |
| 3.— | Stem, with the cryptogamous head or upper end. |