The Metamorphoses of Ovid, Books I-VII

A tumult arising during the celebration of the nuptials, Phineus claims Andromeda, who has been betrothed to him; and together with Prœtus, he and Polydectes are turned into stone. Pallas, who has aided Perseus, now leaves him, and goes to Helicon, to see the fountain of Hippocrene. The Muses tell her the story of Pyreneus and the Pierides, who were transformed into magpies after they had repeated various songs on the subjects of the transformation of the Deities into various forms of animals; the rape of Proserpine, the wanderings of Ceres, the change of Cyane into a fountain, of a boy into a lizard, of Ascalaphus into an owl, of the Sirens into birds in part, of Arethusa into a spring, of Lyncus into a lynx, and of the invention of agriculture by Triptolemus.