Possibly the rushing stream was personified as a steed, and the horse-goddess Epona is occasionally connected with streams, while horses which emerge from lakes or rivers may be mythic forms of water-divinities. In more recent folk-belief the monstrous water-horse of France and Scotland was capable of self-transformation and waylaid travellers, or, assuming human form, he made love to women, luring them to destruction. Did such demoniac horses already exist in the pagan period, or are they a legacy from Scandinavian belief, or are they earlier equine water-divinities thus distorted in Christian times? This must remain uncertain, but at all events they were amenable to the power of Christian saints, since St. Fechin of Fore, when one of his chariot-horses died on a journey, compelled a water-horse to take its place, afterward allowing it to return to the water.20 Akin to these is the Welsh afanc, one of which was drawn by the oxen of Hu Gadarn from a pond, while another was slain by Peredur (Percival) after he had obtained a jewel of invisibility which hid him from the monster with its poisoned spear.21
Mortals as well as síde were transformed Into deer, and fairies possessed herds of those animals, while Caoilte slew a wild three-antlered stag—"the grey one of three antlers"
—which had long eluded the hunters.22 Three-horned animals —bull or boar—are depicted on Gaulish monuments, and the third horn symbolizes divinity or divine strength, the word "horn" being often used as a synonym of might, especially divine power. On an altar discovered at Notre Dame in Paris, the god Cernunnos ("the Horned," from cernu-, "horn".^) has stag's horns; and other unnamed divinities also show traces of antlers. Possibly these gods were anthropomorphic forms of stag-divinities, like other Gaulish deities with bull's horns.23
Serpents or dragons infesting lochs, sometimes generically called péist or béist (Latin bestia, "beast"), occur in Celtic and other mythologies and are reminiscent of earlier reptile
