Passage 9.8.1
διαβεβηκότι δὲ ἤδη τὸν Ἀσωπὸν καὶ τῆς πόλεως δέκα μάλιστα ἀφεστηκότι σταδίους Ποτνιῶν ἐστιν ἐρείπια καὶ ἐν αὐτοῖς ἄλσος Δήμητρος καὶ Κόρης. τὰ δὲ ἀγάλματα ἐν τῷ ποταμῷ τῷ παρὰ τὰς Ποτνιὰς τὰς θεὰς ὀνομάζουσιν. ἐν χρόνῳ δὲ εἰρημένῳ δρῶσι καὶ ἄλλα ὁπόσα καθέστηκέ σφισι καὶ ἐς τὰ μέγαρα καλούμενα ἀφιᾶσιν ὗς τῶν νεογνῶν· τοὺς δὲ ὗς τούτους ἐς τὴν ἐπιοῦσαν τοῦ ἔτους ὥραν ἐν Δωδώνῃ φασὶν ἐπὶ λόγῳ τῷδε ἄλλος πού τις πεισθήσεται.
After crossing the Asopus and going about ten stades from the city, one finds the ruins of Potniae, and within them is a grove sacred to Demeter and Kore. The images of the goddesses are named after the river that runs near Potniae. At a prescribed time, the inhabitants perform certain other established rites, among which is the practice of releasing young pigs into a place they call the Megaron ("sanctuary"). Regarding these pigs, it is said that in the following season of the year at Dodona—on what account another person elsewhere might be convinced—they appear.