of acanthus and vine scrolls. In the western arm's lunette a mosaic represents deer approaching a spring, perhaps a reference to Psalm 42, whose incipit is "As the hart panteth after the water brooks, so panteth my soul after thee, O God." In the southern transept's lunette is a mosaic depicting a male saint carrying a cross accompanied by a burning gridiron and an opened cabinet containing the four canonical Gospels, identified by the names of the Four Evangelists in Latin. Unidentified figures of white-robed martyrs decorate the lunettes of the east and west transepts. The interior of the dome at the centre is decorated as a starry sky, with a regular mosaic of golden stars on a dark blue background, with a gold cross represented at the apex of the dome and the four symbols of the Evangelists (or the "living creatures" of Revelation 4:7) at the corner pendentives. The four lunettes below the dome, between the arches springing from the four central piers and the arches of the pendentives above them, have mosaics each depicting two Apostles with their right arms raised in acclamation likely directed at the male saint in the southern transept's mosaic. The sky with stars or clouds was often depicted as decoration of domes, apses, and ceilings of churches. The basilica in Rome of Saint Pudentiana (Santa Pudenziana), built in the late 4th century, is an example predating Galla Placidia's building, while later buildings at Ravenna repeated the motif, including the Chapel of Saint Andrew (capella Sant'Andrea) in the Archiepiscopal Palace and the 6th century basilica of Saint Apollinaris in Classe (Sant'Apollinare in Classe). North entrance mosaic - the Good Shepherd The figure of the Good Shepherd and pastoral scenes were familiar to Christian thought; depictions of a young man, the criophorus, bearing on his shoulders a sheep were known in the ancient world from the 6th century BC and was adopted from the late 3rd century AD into Christian art, especially in funerary contexts. The shepherd was understood to represent Christ, as in John 10:11-17 and Luke 15:4-7. Here the beardless figure of the shepherd is in imperial garb, wearing purple and gold and bearing a cruciform staff in place of the usual shepherd's crook. He holds an imperial staff joined to the Christian cross, . South transept lunette - male saint The art historian Gillian Mackie argues that this panel represents the