Travellers on the North-Western to Holyhead or Snowdonia are familiar with several cave mouths that form a prominent feature in the Limestone cliffs above Lord Dundonald's castle, near the station of Llandulas. The most conspicuous is a vast antre near the cliff-top; and legend has it that this opens into passages running for great distances, and eventually descending beneath the sea. (Welsh cave-myths are not less extravagant than those of Derbyshire and Somerset, where stories of dogs, geese, and other animals that have made long pilgrimages underground and come into daylight again divested of feathers or hair, are still piously cherished by the credulous.) The name attached to this group of caves, Tanyrogo--"under the cave"--is derived from the Celtic ogo or ogof, a cavern, and is almost identical with the original name of Wookey Hole in Somerset. A party of explorers from Liverpool and Colwyn Bay have recently carried out some researches in the Tanyrogo caves, and in those at St. George, on the other side of Abergele; and while verifying their disbelief in the supposed extent of the subterranean galleries, have ascertained many interesting facts as to the formation and the geological history of both series. A grassy terrace runs along the cliff face to the gaping portal of the Ogo, the biggest of the Tanyrogo caves, which looks seaward and commands a magnificent view over the coast and the Irish sea. The prehistoric men who doubtless lived here once showed not only good taste in the choice of a site for their residence, but a judicious eye for military possibilities; the place is all but impregnable, save by starvation, the only access being by this narrow ledge, which a handful of men could defend against an army. Spanned by a noble arch is a colossal vestibule, rock-floored and dry. But this imposing entrance is a deception--there is nothing beyond to compare with its shape and magnitude. We swerved to the left, and at once found ourselves treading a floor of wet clay, which began to ascend, and soon steepened into a high bank leading up towards the roof. Creeping under an arch, we found ourselves in a transverse fissure that may have run as far as the legends pleased, but grew too narrow in a few feet for any human being to penetrate farther. A few rudimentary stalactites and a crust of pure white calcite adorned one small grotto; the rest was bare rock walls and rugged arches, springing here and there high into the darkness, in fissures that must reach very nearly to the summit of the cliff. A branch passage dwindled away still more quickly, and so did a minor opening that looks like a side door to the main entrance.