Passage 8.42.4
πεποιῆσθαι δὲ οὕτω σφίσι τὸ ἄγαλμα· καθέζεσθαι μὲν ἐπὶ πέτρᾳ, γυναικὶ δὲ ἐοικέναι τἄλλα πλὴν κεφαλήν· κεφαλὴν δὲ καὶ κόμην εἶχεν ἵππου, καὶ δρακόντων τε καὶ ἄλλων θηρίων εἰκόνες προσεπεφύκεσαν τῇ κεφαλῇ· χιτῶνα δὲ ἐνεδέδυτο καὶ ἐς ἄκρους τοὺς πόδας· δελφὶς δὲ ἐπὶ τῆς χειρὸς ἦν αὐτῇ, περιστερὰ δὲ ἡ ὄρνις ἐπὶ τῇ ἑτέρᾳ. ἐφʼ ὅτῳ μὲν δὴ τὸ ξόανον ἐποιήσαντο οὕτως, ἀνδρὶ οὐκ ἀσυνέτῳ γνώμην ἀγαθῷ δὲ καὶ τὰ ἐς μνήμην δῆλά ἐστι· Μέλαιναν δὲ ἐπονομάσαι φασὶν αὐτήν, ὅτι καὶ ἡ θεὸς μέλαιναν τὴν ἐσθῆτα εἶχε.
They say the image was made for them thus: it was seated upon a rock, and in all other respects it resembled a woman except for the head. It had the head and mane of a horse, with images of snakes and other beasts growing out of the head. It wore a tunic that reached down to its very feet, and in one hand it had a dolphin, while on the other hand there rested a dove. As to why the statue was made in such a fashion, this is clear to any intelligent man who is acquainted with traditions. They say that they gave her the name Melaina ("the Black One") because the goddess wore black garments.