A splendid specimen of another species of _Hydatica_, spread out on the surface of the coal-shale, as if expanded on the bosom of the lake in which it grew: the length of the original, a part of which only is figured in the plate, was eight feet, five inches. This species is named by Mr. Artis, _Hydatica prostrata_. The stem is jointed, and slightly striated; the joints are formed with irregular sutures, whence arise tufts of linear leaves resembling those of our common grasses. Fragments of this fossil plant are abundant in the roofs of several of the chambers whence the coal has been extracted, in Elsecar Colliery, Yorkshire. [Illustration: Plate XII.] PLATE XII. "Slender Myriophyllite." The fossil here figured seems to approximate very closely to the Hydatica; but Mr. Artis describes the plant under the generic name of _Myriophyllites_;--_M. gracilis_. The stem is herbaceous and slender, terminating in a point; it is thickly covered with hair-like leaves. It was found imbedded horizontally, in detached masses, separated from the great mass of vegetable matter which covers the coal, by an intervening layer of shale. It is rarely met with in the same bed with other vegetables, but generally in solitary and thin strata, taking a horizontal position; so that by riving the shale which contains these plants, numbers of them are disclosed on the same surface. In its general aspect this fossil vegetable resembles the trailing roots of some aquatic plants. [Illustration: Plate XIII.] PLATE XIII. "Branched Calamite." Long and large jointed stems, generally more or less flattened by compression, and bearing some resemblance to a cane or bamboo, are very abundant in the coal formations. Some of them attain many feet in length, and are of a corresponding magnitude in circumference. The original plants are supposed to have been related to the _Equisetaceæ_, or Mare's-tail, and not to the _Bambusiæ_, and other arborescent grasses. The stem is jointed, and longitudinally striated, having annular impressions at the articulations. The present species (_Calamites ramosus_) has the stem arborescent and branched; the branches are cylindrical, striated, and inserted at the articulations of the trunk; the articulations of the branches are surrounded by a striated disk. The stem has been found nine feet in length, and occurs both horizontally and vertically, in sandstone, in Leabrook Quarry, near Wentworth. [Illustration: Plate XIV.] PLATE XIV. "Doubtful Calamite." These fossil stems are from the same sandstone quarry as the Calamite delineated in the previous plate.