De Incredibilibus

They say that Geryon was three-headed. But it is impossible for a body to have three heads.

Something like this actually happened. There is a city on the Black Sea called Trihead. Geryon was famous among people at that time for his wealth, amongst other things. Heracles came for his marvellous herd of cattle and killed Geryon when he resisted. People who saw the cattle being driven off were amazed: for although they were of small stature, they were long from the head to the loins and had flat noses, no horns, and large, broad bones. And so they would say to anyone who asked, Heracles drove off the cattle belonging to Triheaded Geryon. Because of this response, some thought him to have three heads.

They say that Glaucos was consumed by his horses. What they don’t realise is that he was a breeder of horses and that, because he suffered serious losses and didn’t look after his affairs, he was destroyed.