Passage 2.5.7
οὗτος ὁ Ἆπις ἐς τοσόνδε ηὐξήθη δυνάμεως, πρὶν ἢ Πέλοπα ἐς Ὀλυμπίαν ἀφικέσθαι, ὡς τὴν ἐντὸς Ἰσθμοῦ χώραν Ἀπίαν ἀπʼ ἐκείνου καλεῖσθαι. Ἄπιδος δὲ ἦν Θελξίων, Θελξίονος δὲ Αἴγυρος, τοῦ δὲ Θουρίμαχος, Θουριμάχου δὲ Λεύκιππος· Λευκίππῳ δὲ ἄρρενες παῖδες οὐκ ἐγένοντο, θυγάτηρ δὲ Καλχινία. ταύτῃ τῇ Καλχινίᾳ Ποσειδῶνα συγγενέσθαι φασὶ καὶ τὸν τεχθέντα ὑπʼ αὐτῆς ἔθρεψεν ὁ Λεύκιππος καὶ τελευτῶν παρέδωκέν οἱ τὴν ἀρχήν·
This Apis had grown to such power, before Pelops arrived at Olympia, that the territory within the Isthmus was named Apia after him. The son of Apis was Thelxion, the son of Thelxion was Aigyrus, and his son Thurimachus, and Thurimachus begot Leucippus. Leucippus had no male children, but only a daughter named Calchinia. Poseidon, they say, united himself with this Calchinia, and the child born from her Leucippus reared, and at his death he passed on to him the kingship.