Translation according to P. W. Joyce:
Lispheasty in Galway; Lios-pheiste, fort of the piast or great reptile. See Piast, in vol. i. p. 199 [reproduced below].
Legends of aquatic monsters are very ancient among the Irish people. We find one mentioned by Adamnan (Lib. II., cap. 27), as infesting Loch Ness, in Scotland. In the Life of St. Mochua of Balla, it is related that a stag which was wounded in the chase took refuge in an island in Lough Ree; but that no one dared to follow it "on account of a horrible monster that infested the lake, and was accustomed to destroy swimmers". A man was at last prevailed on to swim across, "but as he was returning the beast devoured him". O'Flaherty (Iar Connaught, c. 19) has a very circumstantial story of an "Irish crocodil", that lived at the bottom of Lough Mask; and in O'Clery's Calendar (p. 145) we read about the upper lake of Glenadalough: - "They say that the lake drains in its middle, and that a frightful serpent is seen in it, and that from fear of it no one ever durst swim in the lake". And in some of the very ancient tales of the Lebor-na-hUidhre we find heroes encountering enormous lake-serpents. This legend assumes various forms in individual cases, and many are the tales the people can relate of fearful encounters with a monster covered with long hair and a mane; moreover, they are occasionally met with in old castles, lisses, caves, etc., as well as in lakes. The word by which they are most commonly designated in modern times, is piast; we find it in Cormac's Glossary in the old Irish form béist, explained by the Lat. Bestia, from which it has been borrowed; and it is constantly used in the Lives of the Irish saints, to denote a dragon, serpent, or monster. Several lakes in different parts of the country are called Loughnapiast, or more correctly, Loch-na-peiste, each of which is inhabited by a demoniacal serpent; and in a river in the parish of Banagher, Derry, there is a spot called Lig-na-peiste (Lig, a hollow or hole), which is the abode of another. When St. Patrick was journeying westward, a number of them attempted to oppose his progress at a place in the parish of Ardcarn in Roscommon, which is called to this day Knocknabeast, or in Irish, Cnoc-an-bpiast, the hill of the serpents. In the parish of Drumhome in Donegal, stands a fort which gives name to a townland called Lisnapaste; there is another with a similar name in the townland of Gullane, parish of Kilconly, Kerry, in which the people say a serpent used to be seen; and near Freshford in Kilkenny, is a well called Tobernapeastia, from which a townland takes its name. There is a townland near Bailieborough in Cavan, called Dundragon, the fort of the dragon, where some frightful monster must have formerly taken up his abode in the old dun. Sometimes the name indicates directly their supernatural and infernal character; as, for instance, in Pouladown near Watergrasshill in Cork, i.e. Poll-a'-deamhain, the demon's hole. There is a pool in the townland of Killarah, parish of Kildallan, Cavan, three miles from Badyconnell, called Longhandoul, or, in Irish, Loch-an-diabhail, the lake of the devil; and Deune Castle, in the parish of Kilconly in Kerry, is the demon's castle, which is the signification of its Irish name, Caislen-a'-deamhain.