CIMRM Supplement - Zodiac. Santa Prisca, Rome, Italy
See also: CIMRM 476 Mithraeum; 477 Cautes; 478 Oceanus / Saturnus; 479 Tauroctony; Paintings: 480 Upper S. wall, 481 Upper S.(contd), 482 Upper N. wall, 483 Upper, Cave , 484 Under S., 485 Under N.; 486-496 Misc. finds; 497-500 Inscriptions and coins; CIMRM Supplement - Zodiac; Intarsio of Sol.
To the left of the main chamber of the Mithraeum are three side chapels. One of these, labelled Y, contains a monument which was a zodiac.
From Vermaseren, Mithriaca II: The Mithraeum at Ponza, p.16:
In the Excavations Vermaseren states (p.140) that the room had dark red stucco of the same colour as the fronts of the podiums; and the room had a layout, rather like a Mithraeum itself with two benches either side:
He goes on to speculate that it may have been the Mithraic equivalent of a baptistry.