angles by shallow squinches, of which the archivolt was decorated with a zigzag ornament in plaster,[34] while at the base of the calotte there has been a similar band of plaster ornament. The construction of this niche recalls with fidelity the terminal semi-dome of a room in the Umayyad castle of Kharâneh (see below, p. 114). Above the calotte there is a small rectangular window (Plate 45, Figs. 1 and 2). The back wall of the niche is exceedingly thin (·45 metre thick) and has in consequence broken away. There is a window high up in each of the side walls of the chamber, ·50 metre from the transverse arch. The remainder of the building appears to have consisted of a single chamber 33·10 metres long. The south-west end is very much ruined. There are traces of five doors on either side, and of a door in the south-west wall. The two doors in either side wall at the north-west end of the chamber were flanked by windows--probably there were more windows, though the ruined condition of the wall makes it difficult to speak with certainty. As regards the roof, there are remains of the spring of a vault in the north-east chamber and on the south-west side of the southern return of the transverse arch. On the exterior, at the north-east end, the wall is set back above the top of the calotte, and immediately below that level the east corner is sliced off diagonally, so as to form a triangular niche which has been partly covered by thin slabs (Plate 45, Fig. 3). Above the level of the calotte the angles of the building on either side appear to have been similarly sliced off. The side windows of the north-east chamber are rounded at the top, but the openings are so small that it was not necessary to construct these arches with voussoirs, and they are merely cut out of the masonry of the wall. The archivolt of the north-east niche is composed of a single row of voussoirs laid horizontally, as is the case in some of the more roughly built arches at Ukhaiḍir (for instance the door of passage 137, Plate 24, Fig. 2). None of the doorways are preserved up to the height of lintel or arch. I am inclined to suppose that this building was connected in some way with the working of the gypsum. It is possible that it may belong to the same period as Ukhaiḍir. MUDJḌAH