The Dracæna (Dragon-blood tree), a tall, slender, elegant tree with amplexicaul leaves (common in our hot-houses), belongs to this family; and certain stems found with Clathrariæ, and bones of the Iguanodon, in the Kentish-rag at Maidstone (ante, [p. 173].), so closely resemble the trunk of this plant, that they have been named by Mr. König,[170] Dracæna Benstedi; the specimens are in the British Museum. Until the internal structure of these fossils has been examined, the correctness of this identification is, however, uncertain: the external resemblance to the stem of the Dracæna consists in the interrupted annular ridges, denoting amplexicaul leaves: no vestiges of the foliage have been observed.
[170] Petrifactions, p. 49.
FRESH-WATER PLANTS. FOSSIL CHARÆ.
Fossil Fresh-water Plants.—The tertiary fresh-water strata often contain abundance of the remains of the aquatic vegetables that inhabited the lakes and rivers in which those deposits were formed. The remains of several species of the common lacustrine plant, the Chara, are found in immense quantities in the fresh-water limestones and marls of the Isle of Wight, of the coast of Hampshire, and of the Paris Basin. The shell-marls, still in progress of formation in the lakes of Scotland, and the travertine precipitated from thermal springs, in like manner envelop and preserve the leaves and fruits of recent species.
Fossil Fruits of Chara. (Gyrogonites.) [Lign. 66.]—The Chara is a well-known inhabitant of almost every stream and rivulet. The stems are hollow, and composed of tubes filled with a fluid in which green globules circulate; they form beautiful microscopic objects for exhibiting the circulation in vegetables. The fruit consists of very small nuclei, contained in a calcareous pericarp, composed of five spirally twisted plates, that unite at the summit. These seed-vessels, when first discovered in a fossil state, were supposed to be the shells of mollusks, and a genus was formed for their reception with the name of Gyrogonites (twisted-stones); a term still employed, though the vegetable nature of these bodies is well known. In Plate III. fig. 5, a branch of the common Chara with seeds is represented: and figures of the seed-vessels, of two fossil species are given in [Lign. 66, figs. 1, 2].
Specimens of the fossil fruits and stems of Charæ, may be collected in abundance in the fresh-water limestone at East Cliff Bay, Isle of Wight.[171]
[171] See my Geology of the Isle of Wight, Lign. 5, p. 109.
