¹ In the Mineralogieal and Geological Gallery of the British Museum (Room III., Table-case 45) is exhibited a very beautiful and slender Obsidian core from Mexico, agreeing closely in general form with those figured in Plate XVI. It is one of the “Cracherode Collection,” and is thus described by the donor:—“Obsidian; Black Volcanio Glass; remarkable for breaking into Prisms; this has 14 sides. From Peru, where they make mirrors of it. Magellan's Cronstedt, p. 917; Kirwan, vol. i. p. 264; Babington, p. 9, sp. 24.” [Cracherode Catalogue.] There are besides three flakes and numerous examples of Obsidian in its unwrought state, both from Iceland and Mexico. Many other specimens of cores and flakes in Obsidian and Flint are exhibited in the Ethnological Department of the British Museum.

² In a subsequent letter to the Editor, General Twemlow states that neither chalk nor flint are found near the spot where the flint cores were embedded, and that the rock is a Limestone.—H. W.