They differ in some respects from the usual type of the genus, hence the specific name (_Calamites dubius_). The striæ are narrow, and have a fine groove running down the middle; the fifth or sixth articulation is surrounded by a double line of large globular indentations, one row belonging to each of the connected joints; these imprints have apparently been left by a zone of some organs which surrounded the articulations, and by its pressure left the indented frill, shown in the upper extremity of fig. 2. These stems are generally found compressed, and from two to three feet in length. Their termination is unknown. This species is figured by M. Ad. Brongniart in Hist. Veg. Foss. tab. 18, figs. 1-3. [Illustration: Plate XV.] PLATE XV. "Pseudo-Bamboo Calamite." (_Calamites pseudo bambusia_, of Sternberg. ---- _Suckovii_, of Brongniart, Hist. Foss. Veg. tab. 14.) "This fossil was found in the clay which fills the fissures of a very fine grit, called by the workmen 'Delf,' that forms a stratum from twenty to twenty-five feet thick, in the quarry at Leabrook, near Wentworth, in Yorkshire. Immediately under this stratum there is a thin bed of very good coal; and at a considerable depth below this bed, there is a second layer of coal, eight feet thick, which is covered in particular places with immense masses of fossil plants." The species here figured very closely resembles the Bamboos. The stem is arborescent, and marked with parallel linear strife, which are intercepted at the sutures; it is simple and cylindrical, and contracted at the articulations; it occurs five feet or more in length. Fig. 1, represents part of the middle of a stem. Fig. 2, shows the gradual upward diminution of the stem, and its pointed termination. [Illustration: Plate XVI.] PLATE XVI. "Short-jointed Calamite." (_Calamites approximatus_, Sternberg. ---- ----, Brongniart, Hist. Veg. Foss. tab. 24.) This species of Calamite is characterized by the shortness and number of the joints; these are intercepted by distinct articulations, and have small compressed tubercles, forming a studded row round the trunk. The articulations are about one-fifth the diameter of the stem apart. The tubercular studs, or warts, are probably the cicatrices of fallen leaves; they rise directly from the articulations, and not from the lower termination of the striæ, as in the species figured in the next plate. The specimen was found imbedded horizontally in soft sandstone, at the bottom of the rock in Hober Quarry, near Wentworth. Fig. 1, represents a portion of the upper part of the trunk, of the natural size, terminating at the top in a sharp compressed point. Fig. 2. An outline on a reduced scale, to show the proportionate size of the stem. [Illustration: Plate XVII.] PLATE XVII. "Ornamented Calamite." (_Calamites decoratus_, Artis. ---- ----, of Brongniart, Hist. Veg. Foss. tab. 14, figs. 1-5.)