Okyrhoe was a daughter of Chiron and Chariklo. Her name means "swift-flowing." She was a prophetess. She was transformed into a mare by Zeus for revealing the secrets of the gods.
Ovid, Metamorphoses 2. 636 ff (trans. Melville) (Roman epic C1st B.C. to C1st A.D.) :
"One day the Centaurus’ [Kheiron’s] daughter came, her auburn hair falling upon her shoulders, whom the Nympha Chariclo once had borne upon the bank beside a flowing river, and had named Ocyroe (Swift-Flowing)."
The Theoi Project