This is a seal from the book "Lesser Key of Solomon". According this text, the spirit Furfur, is described thus
"The Thirty-fourth Spirit is Furfur.
He is a Great and Mighty Earl, appearing in the Form
of an Hart with a Fiery Tail. He never speaketh truth
unless he be compelled, or brought up within a triangle,
A. Being therein, he will take upon himself the
Form of an Angel. Being bidden, he speaketh with a
hoarse voice. Also he will wittingly urge Love between
Man and Woman. He can raise Lightnings and Thunders,
Blasts, and Great Tempestuous Storms. And he
giveth True Answers both of Things Secret and Divine,
if commanded. He ruleth over 26 Legions of Spirits.
And his Seal is this, etc"