The cow-shaped Iö was guarded in Hera's sacred grove at Mycenæ by the hundred-eyed Argus, who was killed by Hermes, by order of Zeus; and Hera next persecuted Iö by a gad fly, which forced her to wander from place to place.[82] Thus Prometheus says: "How should I not hear the daughter of Inachus, who is chased around by the gad fly?" But the wandering of Iö is nothing else than the symbol of the moon, which restlessly moves in its orbit. This is also shown by the very name of Iö (᾽Ιώ), which is derived from the root I (in εἶμι, _I go_). Even in classical antiquity Iö was still frequently represented as a cow; as at Amyclæ.[83] Iö continued to be the old name of the moon in the religious mysteries at Argos.[84] Apis, king of the Argive realm, was the son of Phoroneus, and thus the grandson of Inachus, and the nephew of Iö. From Apis, the Peloponnesus and also Argos were called _Apia_; after his death he was worshipped under the name Serapis.[85] According to another tradition, Apis ceded his dominion in Greece to his brother, and became king of Egypt,[86] where, as Serapis, he was worshipped in the shape of a bull. Æschylus makes the wanderings of Iö end in Egypt, where Jove restores her to her shape, and she bears Epaphus, another name for the bull-god Apis. The cow-horns of the Pelasgian moon-goddess Iö, who became later the Argive Hera and is perfectly identical with her, as well as the cow-horns of Isis, were derived from the symbolic horns of the crescent representing the moon.[87] No doubt Iö, the later Hera, had at an earlier age, besides her cow-horns, a cow's face. Hera, under her old moon-name Iö, had a celebrated temple on the site of Byzantium, which city was said to have been founded by her daughter Keroëssa--i.e., "the horned."[88] The crescent, which was in all antiquity and throughout the Middle Ages the symbol of Byzantium, and which is now the symbol of the Turkish empire, is a direct inheritance from Byzantium's mythical foundress, Keroëssa, the daughter of the moon-goddess Iö (Hera); for it is certain that the Turks did not bring it with them from Asia, but found it already an emblem of Byzantium. Hera, Iö, and Isis, must at all events be identical also with Demeter Mycalessia, who derived her epithet "the lowing," from her cow-shape, and had her temple at Mycalessus in Bœotia. She had as door-keeper Hercules, whose office it was to shut her sanctuary in the evening, and to open it again in the morning.[89] Thus his service is identical with that of Argus, who in the morning unfastens the cow-shaped Iö, and fastens her again in the evening to the olive tree,[90] which was in the sacred grove of Mycenæ, close to the ῾Ἡραῖον.[91] The Argive Hera had, as the symbol of fertility, a pomegranate, which, as well as the flowers with which her