Annotations to James Joyce's Ulysses/Circe/556
Introibo ad altare diaboli (Latin) I will go in to the altar of the devil. In the context of the Black Mass which is being parodied here, Father O'Flynn subverts the words of the Prayers at the Foot of the Altar from the Latin Tridentine Mass, which Mulligan quoted on the opening page of the novel. See 003.05. The correct form, however, is: Introibo ad altare Domini Inferi (I will go in to the altar of the Lord of Hell).
Corpus Meum (Latin) My Body. During the Consecration of the Host in the Latin Tridentine Mass, the celebrant elevates the host and says: Hoc est enim corpus meum (For this is my body). In the Black Mass, which is being parodied here, the corresponding words are: Hoc est corpus Jesu Christi (This is the body of Jesus Christ).
In some editions of Ulysses, this phrase is emended to Corpus meum.