In our examination of the church we turn first to the presbytery, which is entirely encrusted with most precious marbles and mosaics. In the midst of it stands the altar consisting of slabs of semi-transparent alabaster, within which of old lights were set. The marvellously lovely piece which serves for the altar stone itself is supported by four columns, and that piece which serves for frontal is carved with a great cross between two sheep. This altar had long disappeared, but piece by piece it was recovered; the beautiful altar stone itself was found behind an altar in a chapel now destroyed in this church, and was re-erected as we see it in 1899. [Illustration: Colour Plate S. VITALE: THE PRESBYTERY] In the same chapel stood till then the beautiful low fretted screens that now are set across the apse behind the altar, where indeed they remained till 1700, according to Dr. Ricci. The lower part of the apse and the piers of the presbytery have been covered with fine marbles, some of which are ancient, but the vault, the lunettes, and the walls are entirely encrusted with gorgeous mosaics. The presbytery is approached from the inner octagon of the church under a triumphal arch. In the curve of this we see amid much decorative ornament fifteen circular discs containing the head of Our Lord, the twelve Apostles, S. Gervasius, and S. Protasius. Beneath these are two monuments variously formed, Dr. Ricci tells us, in the sixteenth century. The four columns which they contain originally supported the baldacchino over the high altar here; three of them are of verde antico. Framed by these columns are two Roman reliefs from a frieze originally in the Temple of Neptune, other parts of which are in the Sala Lapidaria in the Arcivescovado here, in the Louvre, in the Uffizi, in the Castello of Milan, and in the Museo Archeologico at Venice. They are indubitably of course the oldest things in the church.