Passage 7.1.3
ἀφικομένῳ δὲ ἐς τὸν Αἰγιαλὸν καὶ οἰκήσαντι αὐτῷ μὲν ἐγένετο ἐνταῦθα ἡ τελευτή, τῶν δέ οἱ παίδων Ἀχαιὸς μὲν ἐκ τοῦ Αἰγιαλοῦ παραλαβὼν καὶ ἐξ Ἀθηνῶν ἐπικούρους κατῆλθεν ἐς Θεσσαλίαν καὶ ἔσχε τὴν πατρῴαν ἀρχήν, Ἴωνι δὲ ἐπὶ τοὺς Αἰγιαλεῖς στρατιὰν καὶ ἐπὶ Σελινοῦντα τὸν βασιλέα αὐτῶν ἀθροίζοντι ἀγγέλους ἔπεμπεν ὁ Σελινοῦς, τὴν θυγατέρα Ἑλίκην, ἣ μόνη οἱ παῖς ἦν, γυναῖκα αὐτῷ διδοὺς καὶ αὐτὸν Ἴωνα ἐπὶ τῇ ἀρχῇ παῖδα ποιούμενος.
When he had arrived in Aigialos and settled there, he himself came to his end in that place. Of his sons, Achaios departed from Aigialos, and having gathered allies from Athens, went down into Thessaly and took possession of his ancestral domain. Ion, meanwhile, was mustering an army against the people of Aigialos and their king Selinous; but Selinous sent envoys to him, offering his daughter Helike, who was his only child, as wife, and adopting Ion himself as son and successor to his throne.