Half-Olympian son of Apollo by Evadne daughter of Poseidon and Pitane. The Pindaric narrative (Olympian 6.28-72, written ca. 472-468 BCE for the Olympic victory of Hagesias of Syracuse, an Iamid mantis) is the foundational reference. Evadne, reared in Arcadia by Aepytus king of Phaisana, was lain with by Apollo and gave birth secretly in a meadow with the Fates and Eleithyia attending. She concealed the infant in a thicket of violets and rushes; two grey-eyed serpents fed him honey for five days, until herdsmen searching found him "drenched in the gold-and-purple light of violets" — whence Evadne named him Iamus from the violets (ἴα). On reaching young manhood, descended into the middle of the Alpheus river and called on his maternal grandfather Poseidon and his father Apollo for honor among men. Apollo answered, calling Iamus to Cronion's height (the hill of Olympia), and gave him a twofold treasure of prophecy — first the voice-of-truth-hearing, and afterwards (when Heracles should establish the Olympic rite) the empyromantic divination at the great altar of Zeus. Established the Iamidae prophet-clan at Olympia, who held hereditary divinatory rights at the great altar of Zeus continuously from the archaic period through the Roman imperial era — the most prominent hereditary mantis-clan of ancient Greece. The most-famous Iamid mantis Tisamenus, recorded by Herodotus 9.33-35, prophesied at Plataea (479 BCE) the Greek victory over the Persians and was granted Spartan citizenship as reward (a unique Spartan honor). The serpentine-feeding-with-honey is the mantic-initiation moment shared with the Tiresias and Melampus narratives — Iamus's personal mantic-anointing fitting him into the broader Apollonian-mantis-initiation pattern.