Arca, a box in which the Eucharist was kept by the primitive Christians in their homes. St. Cyprian (De lapsis, xxvi) tells of a woman ‘who with unworthy hands” attempted “to open her box in which was the Holy (Body) of the Lord”, but was unable to do so because of fire which issued therefrom the moment she touched it. (Cum quaedam arcam suam in quo Domini sanctum fuit manibus immundis temptasset aperire, etc.) A representation of the Eucharistic Arca is believed by Wilpert to exist in a fresco of the catacomb of Sts. Peter and Marcellinus. The scene depicts Christ seated, reading from an open roll; on His right are three amphore, and on the left a square box filled with loaves, symbols of the Eucharist. It also signified a receptacle for the offerings of Christians for the Church or the poor (Tert., Apol., xxxix; Liber Pontif., I; 154).
5 gala Kealencyclop., 73; Henry in Dict. d’arch. chrét., I,
Maurice M. Hassett.