CHAPTER XX.

SUBTERRANEAN RELICS OF PREHISTORIC MAN.

The Peat Mosses of Denmark—Shell-Mounds—Swiss Lacustrine Dwellings—Ancient Mounds in the Valley of the Mississippi—The Caves in the Valley of the Meuse—Dr. Schmerling—Human Skulls in the Cave of Engis— Explorations of Sir Charles Lyell in the Cave of Engihoul—Caverns of Brixham—Caves of Gower—The Sepulchral Grotto of Aurignac—Flint Implements discovered in the Valley of the Somme—Gray’s Inn Lane an ancient Hunting-Ground for Mammoths 221