The demon Furcas appears in the grimoires Book of Incantations, The Discoverie of Witchcraft, Pseudomonarchia Daemonum, and The Lesser Key of Solomon
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Fiftieth Spirit is Furcas. He is a Knight, and appeareth in the Form of a Cruel Old Man with a long Beard and a hoary Head, riding upon a pale-coloured Horse, with a Sharp Weapon in his hand. His Office is to teach the Arts of Philosophy, Astrology, Rhetoric, Logic, Cheiromancy, and Pyromancy, in all their parts, and perfectly. He hath under his Power 20 Legions of Spirits. His Seal, or Mark, is thus made, etc.