Passage 5.15.7
ἐσελθόντων δὲ αὖθις διὰ τῆς πομπικῆς ἐς τὴν Ἄλτιν, εἰσὶν ὄπισθεν τοῦ Ἡραίου Κλαδέου τε τοῦ ποταμοῦ καὶ Ἀρτέμιδος βωμοί, ὁ δὲ μετʼ αὐτοὺς Ἀπόλλωνος, τέταρτος δὲ Ἀρτέμιδος ἐπίκλησιν Κοκκώκας, καὶ Ἀπόλλωνος πέμπτος Θερμίου. τὸν μὲν δὴ παρὰ Ἠλείοις Θέρμιον καὶ αὐτῷ μοι παρίστατο εἰκάζειν ὡς κατὰ Ἀτθίδα γλῶσσαν εἴη θέσμιος· ἀνθʼ ὅτου δὲ Ἄρτεμιν ἐπονομάζουσι Κοκκώκαν, οὐχ οἷά τε ἦν μοι διδαχθῆναι.
Upon entering again into the Altis through the ceremonial gateway, there stand behind the Heraion altars of the river Kladeos and of Artemis, followed by an altar of Apollo; fourth is one of Artemis who bears the surname Kokkoka, and fifth one of Apollo Thermios. Concerning Thermios, the Elean usage itself suggested to me conjecturing that the name corresponds to the Attic term "Thesmios" (Lawgiver); but for what reason Artemis is called Kokkoka I was unable to ascertain.