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Oncius

In Greek mythology, Oncius or Oncus was a son of Apollo and a ruler over Ónkeion (Ὄγκειον), a region of Arcadia adjacent to Thelpusa, as well as eponym of a city Oncae. He owned a herd of horses, in which Demeter tried to hide from Poseidon's advances, changing herself into a mare. Poseidon did mate with her in the shape of a stallion, which resulted in the birth of the fantastic horse Arion. Oncius kept Arion and later gave him away to Heracles as the latter was starting a military campaign against Elis.

Last revised
Jun 4, 2026
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In Greek mythology, Oncius (Ancient Greek: Ὄγκιος, romanizedÓnkios, lit.'case for arrowheads') or Oncus (Ancient Greek: Ὄγκος, romanizedÓnkos, lit.'point of an arrow')1 was a son of Apollo and a ruler over Ónkeion (Ὄγκειον), a region of Arcadia adjacent to Thelpusa,23 as well as eponym of a city Oncae.4 He owned a herd of horses, in which Demeter tried to hide from Poseidon's advances, changing herself into a mare. Poseidon did mate with her in the shape of a stallion, which resulted in the birth of the fantastic horse Arion. Oncius kept Arion and later gave him away to Heracles as the latter was starting a military campaign against Elis.5

Notes

Notes

  1. Liddell Scott s.v. ὄγκιον & ὄγκος (Α)
  2. Pausanias, Description of Greece, 8. 25. 4
  3. Stephanus of Byzantium s. v. Onkeion
  4. Etymologicum Magnum, 613. 43
  5. Pausanias, Description of Greece, 8. 25. 5 & 10
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