(), a son of Apollo and Asteria, the daughter of
Coronus (Schol. ad Apollon. Rhod. 1.139), or, according to others, of
Apollo, by Antianeira, of Ampycus, or of Apollo and Cyrene. (Orph. Arg.
185, &c., 721; Apollon. 1.139, &c.; Hyg. Fab. 14; comp. V. Fl. 1.228.) He
was one of the soothsayers who accompanied the Argonauts : his name signifies " the knowing,"
and has been considered to be a mere epithet of Thestor or Mopsus. (Schol. ad
Apollon. Rhod. 1.139.) He joined the expedition of the Argonauts, although he knew
beforehand that death awaited him. He was killed in the country of the Mariandynians by a boar
or a serpent; or, according to others, he died of a disease. (Apollod. 1.9.23; Apollon. 1.140, 443, 2.815, &c.; V. Fl. 5.2, &c.) The Megarians and Boeotians who were to found
Heracleia, were commanded by Apollo to build the town round the tomb of the hero, and to
worship him as the protector of the place. (Apollon. 2.846,
&c.) There are three other mythical personages of the name of Idmon. (Apollod. 2.1.5; Ov. Met. 6.8, 138; Stat. Theb. 3.389.)