we have just returned from nomandy france. while there we accidentally ran over a snake, cutting its head off. It was about a foot long, quite thin and dark brown with a thin black line the length of its body. there were no diamonds or zigzags on it. anyone know what it could be ? our french neighbour said if the pupils of its eyes were vertical slits it was venemous but if its pupils were round it was harmless,since the head was unrecognisable as such (its mother wouldn't know it) we have no idea what it was.