_Stone Lake Dwellings._--On some of these artificial islands the last structures seemed to have been formed of stone: for example, in Loughtamand, county Antrim, a stone house or castle, the stronghold of the MacQuillans, replaced a circular structure composed of wood; a similar change seems to have been made in one of the crannogs of Loughrea. The transition from buildings of wood to those of stone has also been observed in Scotland. Mention may be made of a few stone-built island fortresses; and although, strictly speaking, the term “crannog” is scarcely applicable, yet many of them that present a modern appearance are structures erected on ancient foundations. In parts of Galway and Mayo, where timber was either scarce or of stunted growth, buildings of stone seem to be most numerous, whilst in Ulster they occur in the rocky districts of Antrim and Donegal. Goromna Island, in Lough Hilbert, county Galway, is a peculiar structure, which, though not formed of wood, is somewhat allied to a crannog, being wholly or in part an artificial island. A large and good specimen, _Caislen-na-Caillighe_, or the Hag’s Castle, stands in Lough Mask. It is one of the oldest fortresses mentioned in the Irish Annals, being noticed at the date A.D. 1195. In 1233 the Anglo-Norman castle erected on its site was demolished by Felim O’Conor, chief of Connaught, and so late as 1586 it was with difficulty captured by Sir Richard Bingham. This great circular enclosure, ninety feet in diameter and thirty feet in height, occupies almost the entire island. The walls, which are still eight feet in depth at top, exhibit the characteristic inward slope peculiar to the cashel; its situation near the mouth of a river (the Robe) is characteristic of crannogs. In Lough Bola there is a curious cashel, or stone lake dwelling; the accompanying sketch gives an idea of its present appearance. A primitive habitation lies in Lough Cam, north of Roundstone, and two miles west of Toombeola. All these islands have a crannog-like aspect. To the south of Ballinahinch lake lies that of Ballinafad, and in its northern portion there becomes visible, when the water is low, a circle of stones and a small island, evidently the remains of some artificial structure. O’Flahertie, in his _History of Iar-Connaught_, mentions that the ancient castle of the O’Flaherties of Bunowen, in the lake of Ballinahinch, was built on an artificial island: this had been constructed by one of the original septs long prior to the occupation of the country by the O’Flaherties, who in their turn were driven out by the Martins.[51] [Illustration: Fig. 3.--Stone Lake Dwelling in Lough Bola.]