the east end is repeated at the west end, but the band between the crenellations and the flutes of the quarter-domes is omitted. The miḥrâb niche is not placed exactly in the centre of the south wall, but a few centimetres to the east (Plate 18, Fig. 2). If there was any stucco ornament upon it, it was all carried away by the fall of the vault. The semi-dome which covers it is set over the rectangular niche on horizontal brackets of masonry, like all other semi-domes and calottes in the palace. The archivolt is constructed of a double ring of voussoirs, the inner ring laid vertically, the outer horizontally. There is no reason to doubt that the miḥrâb is contemporary with the wall. The plaster which remains upon the interior of the semi-dome shows no sign of decoration. Below the semi-dome the face of the walls of the niche is much injured by the heavy masses of fallen masonry. The angle pier which took the corner arches of the ḥaram and the east arcade shows, on the sides facing the arcades, returns in the shape of engaged columns. A third return is rectangular and corresponds with a return on the east wall, the two carrying the transverse arch which terminates the eastern vault. In the fragment of this vault which is standing the principles of construction can be discerned unusually well (Plate 19). The vault is built of thin slabs of stone, laid in rings, with a marked inclination against the northern head wall. At the southern end these rings fan out so as to meet the transverse arch. One more detail remains to be noticed. The two doors from the west corridor, 5, stand in recesses 1 metre deep. The recesses are covered by a calotte, and round the archivolt is placed a stucco decoration consisting of seven cusps (Plate 21, Fig. 1).