Salamander is the common name for about 500 species of amphibians which resemble lizards that live in and near water.
They are unique among vertebrates for their ability to regenerate lost limbs and other body parts, which probably explains why many regarded them as magical creatures, especially in medieval times.
Salamanders were sometimes thought to be born out of fire, or to be able to put out fire with their moist skin. The illustration on the right is an image of a magical salamander from a 16th century text called The Story of Alchemy and the Beginnings of Chemistry. Such associations were mentioned by the Talmud, Benvenuto Cellini, Paracelsus, and Leonardo da Vinci. (Note: the fire engine in Fahrenheit 451 is known as the "Salamander.")
As Jim sneaks off to the carnival without Will, the narrator evokes these magical associations.