One dwelling of three storeys, with flights of steps in good preservation, is called the Castle by the peasants. Parthey, a German traveller, who investigated these dwellings, reckoned their number to be over 1500. He saw nowhere any trace of ornament about them. Doors and windows were mere rough holes cut through the limestone. Rings hewn in the stone which are found in the chambers probably served some purpose of domestic economy. Fragments of Samian ware and carved marble have been found in them, but are probably later than the construction of these habitations. Some contain graves, and these also may be later, but actually we know from history nothing about them. Rock tombs may have been utilised as dwellings or abandoned dwellings as tombs. To the present day some of them are still occupied, mainly by shepherds and poor peasants. The range in the Crimea from Cape Kersonese to the Bay of Ratla is formed of layers of limestone alternating with clay and argilaceous schist, a disposition of the strata that tends greatly to accelerate the disintegration of the cliffs. The clay gradually washed out by springs or eaten away by the weather forms great caverns in the sides, and these are liable to fall in when deprived of support. They have, however, been utilised as habitations. The Rock of Inkermann, the ancient Celamita, runs east of the town beyond the marshy valley of the Chernaya; it has been converted into a vast quarry which menaces with destruction the old Troglodyte town that occupied the cliffs. The galleries of this underground town form a rabbit warren in which it is dangerous to penetrate without a guide or a clue. Some of the chambers are large enough to contain five hundred people. The rocks of Djonfont-kaleharri are also honeycombed, with still inhabited caves; some are completely cavernous, but others have the openings walled up so as to form a screen. Beneath an overhanging rock is a domed church used by this Troglodyte community. If we cross the Mediterranean to Egypt, we see there whole villages of cave-dwellers. The district between Mansa-Sura and Cyrene is full of grottoes in the very heart of the mountains, into which whole families get by means of ropes, and many are born, live and die in these dens, without ever going out of them. The volcanic breccia as well as chalk and limestone has been utilised for the habitation of man. There is a very interesting collection of cave-dwellings all artificial, the Balmes du Montbrun, a volcanic crater of the Coiron, near S. Jean le Centenier in the Vivarais. The crater is 300 feet in diameter and 480 feet deep; and man has burrowed into the sides of porous lava or pumice to form a series of habitations, a chapel, and one that is traditionally said to have served as a prison. This rock settlement was occupied till the close of the eighteenth century.