The Medals of Creation, Volumes 1 and 2 / First Lessons in Geology and the Study of Organic Remains

by Gideon Algernon Mantell

Chalk-marl, Lewes.

Showing the form of the aperture, and the spinous tubercles. The specimen is a cast in indurated chalk-marl; the last wreath only is figured.

Fig.	1.—	Posterior view, exhibiting the expanded outer lip, and the obtuse termination of the columella.
	2.—	Front view, showing the form of the aperture. a.—Two tubercles, bearing spines.

The Chalk-marl of Lewes, of the Sussex coast, and of the cliffs near Dover, and the Upper Green Sand of Dorsetshire, have yielded the principal British specimens of this genus. Several species occur in the lower cretaceous strata, at St. Catherine’s Mount, near Rouen, associated, as in England, with Scaphites, Hamites, and other allied genera.[426]

[426] See Fossils of the South. Downs for figures of many species of the Cephalopoda of the Sussex Chalk.

APTYCHUS.

Lign. 165. Aptychus sublævis. ¹/₂ nat.
Kimmeridge Clay, Hartwell, Bucks.

Fig.	1.—	The convex surface.
	1a.—	Magnified section of portion.
	2.—	The concave side.