Passage 6.21.1
τὸ δὲ ἕτερον τοῦ ἱπποδρόμου μέρος οὐ χῶμα γῆς ἐστιν, ὄρος δὲ οὐχ ὑψηλόν. ἐπὶ τῷ πέρατι τοῦ ὄρους ἱερὸν πεποίηται Δήμητρι ἐπίκλησιν Χαμύνῃ· καὶ οἱ μὲν ἀρχαῖον τὸ ὄνομα ἥγηνται, χανεῖν γὰρ τὴν γῆν ἐνταῦθα τὸ ἅρμα τοῦ Ἅιδου καὶ αὖθις μύσαι· οἱ δὲ Χάμυνον ἄνδρα Πισαῖον Πανταλέοντι ἐναντιούμενον τῷ Ὀμφαλίωνος τυραννοῦντι ἐν Πίσῃ καὶ ἀπόστασιν βουλεύοντι ἀπὸ Ἠλείων, ἀποθανεῖν φασιν αὐτὸν ὑπὸ τοῦ Πανταλέοντος καὶ ἀπὸ τοῦ Χαμύνου τῆς οὐσίας τῇ Δήμητρι οἰκοδομηθῆναι τὸ ἱερόν.
The other part of the hippodrome is not a mound of earth, but a hill, though not a high one. At the far end of this hill there is a sanctuary dedicated to Demeter, surnamed Chamynē. Some consider this surname ancient, asserting that here the earth opened (chanein) to admit Hades' chariot and afterward closed again. Others say that Chamynos was a man from Pisa who opposed Pantaleon, the son of Omphalion who was tyrant in Pisa and plotted revolt against the Eleans. They relate that Chamynos was killed by Pantaleon, and from Chamynos' property the sanctuary for Demeter was built.