A Broch like Clickamin is practically a lake-dwelling—Many Pages defensive structures in lakes which are not 260–307 Brochs—Defensive structure in the Loch of Hogsetter, Whalsay—Its special peculiarities—Lake-dwellings constructed of wood, known as Crannogs—The Crannogs of the Loch of Dowalton—The Crannogs of Ayrshire—General similarity of the groups of objects recovered from them to those found in Brochs—No class of ancient remains of which we have less precise knowledge than Hill-Forts—They differ essentially from all other structures—They are of two varieties, earthworks and stoneworks—Character of the earthworks—Earthwork on Midhill Head, Midlothian—Stone fort at Garrywhoine, Caithness—The White Caterthun, Forfarshire—Fort on Ben Ledi—The vitrified forts—Knockfarril in Strathpeffer—Craig Phadrig, near Inverness—Fort at Finhaven, Forfarshire—Dun Mac Uisneachan, in Loch Etive—Forts in Arisaig, Inverness-shire—Vitrified forts do not differ in character from forts that are not vitrified, if their vitrifaction be not a feature of their construction—The evidence insufficient to establish that the vitrifaction was a method of construction—The phenomena of the vitrified forts in France—The Gaulish forts constructed with alternate layers of logs and stones—Similar construction of the great rampart of Burghead in Morayshire—The hill-fort of Dunsinnane associated with underground chambers—Similar association in the forts of Ireland—Underground chambers not associated with forts—The “Earth-Houses” at Broomhouse, Berwickshire—In Strathdon, Aberdeenshire—Groups of them at Airlie, Forfarshire, and Kildrummy, Aberdeenshire—Associated with an overground habitation and a group of graves at Grange of Conan, Forfarshire—With objects of the Roman period at Tealing, Pitcur, Newstead, and Crichton Mains—The range and period of this type of structure—The culture and civilisation of the people who constructed them INDEX 309 LIST OF ILLUSTRATIONS.