All this was proved in the demonstration. At the source of the Amymone grows a plane tree, beneath which, they say, the hydra （water-snake） grew. I am ready to believe that this beast was superior in size to other water-snakes, and that its poison had something in it so deadly that Heracles treated the points of his arrows with its gall. It had, however, in my opinion, one head, and not several. It was Peisander1
of Camirus who, in order that the beast might appear more frightful and his poetry might be more remarkable, represented the hydra with its many heads.