CS Lewis, The Silver Chair (London, 1998), Chapter 14, p. 191.
live in the subterranean fire;
are the only beasts that do so;
are too white-hot to look at;
but most like small dragons;
speak to the Underworlders out of the fire;
are witty and eloquent.
That is all that I can find but it is enough to make a comparison with the salamanders of Poul Anderson, Alan Moore, Tim Powers and Robert Heinlein.