This is a seal from the book "Lesser Key of Solomon". According this text, the spirit Phenex, is described thus
"The Thirty-Seventh Spirit is Phenex
(or Pheynix). He is a great Marquis, and appeareth
like the Bird Phoenix, having the Voice of a Child. He
singeth many sweet notes before the Exorcist, which he
must not regard, but by-and-by he must bid him put on
Human Shape. Then he will speak marvellously of all
wonderful Sciences if required. He is a Poet, good and
excellent. And he will be willing to perform thy requests.
He hath hopes also to return to the Seventh
Throne after 1,200 years more, as he paid unto Solomon.
He governeth 20 Legions of Spirits. And his Seal is
this, which wear thou, etc"