Sources : Siren (Serpent)

Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:29): In Arabia there are snakes with wings, called sirens (sirena); they move faster than horses, but they are also said to fly. Their venom is so powerful that when someone is bitten by them death ensues before the pain is felt. - [Barney, Lewis, et. al. translation]