Details of the dome are given in Salzenberg’s Plate xxvi. The edges of the ribs and window openings are covered with bands of ornament. The faces of the ribs have alternate squares and crosses, which decrease in size as they get higher. The central space has lost its figure subject, but it is surrounded by a wide border.[379] The sides of the window openings are lined with silver mosaic. The lower part of the dome is not decorated, as the projecting cornice hides it from below.[380] The edges of the exedra-conchs have bands similar to those on the great arches, and the same pattern occurs again on the edges of the eastern barrel vault, and the bema apse.[381] The rest of the decoration of the surface of the apses has disappeared. Over the centre door from the narthex to the nave is represented Christ on a throne, holding a Gospel open at the words, “I am the Light of the world: Peace be with you.” A monarch is prostrate before him, and in medallions on either side are Mary the Intercessor, and Michael the Protector.[382] The nimbus of Christ has three rays, and His hand blesses in the Greek manner, by which the fingers represent the initial and final letters of Jesus Christus. The undergarment has broad gold stripes worked on it, and the lights are given in silver; it seems to be of silk, the upper garment appears to be of a white woollen stuff. The great western arch has a medallion of the Virgin at the crown, and full lengths of Peter and Paul at the sides, Peter on the south; however, only a few remnants of these figures are now left. The border which surrounds the medallion of the Virgin has colours of the rainbow, the circle of her halo is red; the flesh colour is fair, and the eyes are blue. The veil is blue, with a gold cross, and the cloak is also blue. Under the veil is a kind of band round the head, like that which the Spanish Jews of Constantinople wear; it is of a blue green colour with dark stripes; the hair is not visible. Her nimbus has three silver rays on a gold ground; her hands rest on the shoulders of the Child, whose right hand blesses, while the left holds the book of the Gospel. Peter’s face is dark, the nimbus is blue, the garment is bluish green, and the gold rod, surmounted by a cross, has red and blue bands. He thus has the same insignia as the St. Peter on the Ciborium Curtain, and it is this which, in the mosaic, identifies the figure as Peter, for there is no inscription. Porphyrogenitus, in his life of Basil, mentions that when the western arch was restored the pictures of the Virgin, and the Apostles Peter and Paul were placed there by that emperor. The figure of Paul has an upper garment of green with silver lights, and the undergarment is a greenish yellow. The whole figure is about seventeen feet high, but the head is wanting.[383]