An snake so poisonous that those bitten die before they feel pain
The name siren is usually used for the beast part woman, part fish and/or bird; it is also the name of a snake.
The name siren has been used for a white snake with wings; Isidore of Seville says that in Arabia there are winged snakes called sirens whose bite is followed by death before pain. This description seems to be a combination of that of the dipsa and the jaculus.
Uses Magical, Medical, Alchemical and Culinary
The siren snake signifies those who are conscious of sin and full of remorse when they commit sins, and yet are so miserable and weak that they allow themselves to be overcome by wicked temptation. [Thomas of Cantimpré]