Thelpusa in the context of "Arion (horse)"

In Greek mythology, Arion or Areion (/əˈraɪ.ən/;Ancient Greek: Ἀρίων, Ἀρείων), is a divinely-bred, fabulously fast, black-maned horse. He saved the life of Adrastus, king of Argos, during the war of the Seven against Thebes.

Arion was (by most accounts) the offspring of Poseidon and Demeter. When the goddess Demeter was searching for her daughter Persephone, she was pursued by Poseidon. To escape Poseidon, Demeter turned herself into a mare and hid among the mares of Oncius, king of Thelpusa in Arcadia. But Poseidon turned himself into a stallion and mated with Demeter, fathering Arion. Other accounts had Arion as the offspring of Gaia (Earth), or of Zephyrus and a harpy.