The demon Ipos appears in the grimoires The Discoverie of Witchcraft, The Book of Spirits, Pseudomonarchia Daemonum, The Lesser Key of Solomon, and Dictionnaire Infernal
From The Lesser Key of Solomon, Crowley/Mathers edition:
The Twenty-second Spirit is Ipos. He is an Earl, and a Mighty Prince, and eppeareth in the form of an Angel with a Lion's Head, and a Goose's Foot, and Hare's Tail. He knoweth all things Past, Present and to Come. He maketh men witty and bold. He governeth 36 Legions of Spirits. His Seal is this, which thou shalt wear, etc.