In this species of Calamite the joints are short, and decrease in length towards the summit, where they terminate in an enlarged rounded head. The striæ are ornamented with tubercles at the bottom, close to the articulation. The striæ are broader, and the tubercles larger, towards the summit. The stem is sometimes found two feet long, and from two to four inches in diameter. The situation of the tubercles at the lower extremity of the striæ, is a striking feature of this species; and the termination of the summit of the stem is remarkable for its obtuseness. The specimen is from Leabrook Quarry, Yorkshire. [Illustration: Plate XVIII.] PLATE XVIII. "Transverse Sternbergia." (_Sternbergia transversa_, of Artis. _Artesia_ ----, of Presl. Additions to Sternberg's _Flora der Vorwelt_.) The stems known by the name of _Sternbergia_, (from Count Sternberg, the author of the Fossil Flora,) appear to be related to the Yucca, or to the Pandanus or Screw-pine. Mr. Artis observes, that they bear considerable analogy to the stems of the _Stapeliæ_ of our gardens; but still, the external form, which Is the only character visible, does not furnish sufficient ground for their being positively referred to that genus. The stem is marked longitudinally with double keels or ridges, which terminate at different heights spirally round the stem, and have small tubercles at their terminations. There are likewise slight annular depressions, mostly distinct, but in some places two or more unite. The stem is straight, simple, and cylindrical, and is compressed towards the summit. It is sometimes found six feet in length, and from one to four inches in diameter. It is generally coated with a carbonized bark. Fig. 1, shows a portion of the stem of the natural size. Fig. 2. The upper extremity, in which the tubercular terminations of the double keels or ridges are seen at A, B. Found associated with Calamites in the clay-bind of Leabrook Quarry. [Illustration: Plate XIX.] PLATE XIX. "Fibrous Sigillaria." (_Rhytidolepis fibrosa_, of Artis.)