μώνυχες Ἀόνιοι, στικτὸν γένος, οἰοκέρωτες, ἔκ τε μέσου κέρας αἰνὸν ἐπαντέλλουσι μετώπου.
English translation (A.W. Maire, 1928)Edit
The Aonian Bulls do not divide the hoof; a dappled breed they are and with a single horn – a dread horn which they project aloft from the midst of the forehead.
Aonia is a poetic name for Boeotia – a region in Central Greece. Placing such a strange and unknown animal (because other authors know nothing about it) in a familiar place is highly surprising and rousing a suspicion that the author really meant India and Indian asses known from Ctesias. The word "στικτὸν" means "dappled, marked, tattooed" and likely refers to the diverse coloration of the beasts.