ACIS, in Mythology, the son of Faunus and the nymph Symrethis, was a beautiful shepherd of Sicily, who being beloved by Galatea, Polyphemus the giant was so enraged that he crushed his rival with a rock, and his blood gushing forth from under the rock, was metamorphosed into the river bearing his name (Ovid, Met. xiii. 750; Sil. Ital. xiv. 221). This river, now Fiume di Jaci, or Acque Grandi, rises under a bed of lava on the eastern base of Etna, and passing Aci Reale, after a rapid course of one mile, falls into the sea. The waters of the stream, once celebrated for their purity, are now sulphureous.