whole into an apparent symmetry which an analysis of the details proves to be lacking in reality. Ukhaiḍir, separated from Ctesiphon by an interval of some 500 years, shows a sensible advance. The north façade of the court is not indeed centralized, nor is it symmetrically placed in the wall of the three-storied block, but the two lower zones are organically connected with one another. The seven blind niches of the lower order correspond with those of the second order. In the second order the breaking up of the zone into registers is still adhered to, but since an archivolt has taken the place of the architrave of Ctesiphon, the principle is not so strongly marked. It works only within the arched niches. That it is substantially the same is, however, apparent from the fact that at Ukhaiḍir, as at Ctesiphon, the lower register consists of groups of two small niches, the upper register of groups of three, the central niche being the largest. The seven large niches of the second order are separated by a cluster of four columns; in the spandrels of the arches there are niches containing windows. The pylon-like wall of Ctesiphon is represented by a battered wall at Ukhaiḍir, but instead of sloping back and forming horizontal ledges, its perpendicular face seems to have been divided at intervals by horizontal bars of masonry. There is no space between the zones for important horizontal mouldings. Dr. Reuther in his reconstruction (_Ocheïdir_, Plate 25) places a plain masonry balcony along the narrow platform formed by the summit of the second zone. It is, however, conjectural, and in my opinion it lays a stress upon the horizontal divisions between the zones which is contrary to the spirit of the decorative scheme. In the upper zone the plain wall is in far better accord with the classical treatment of wall-surfaces than are the restless nichings of Ctesiphon, and it enhances the value of the rich orders below it. But it is not regarded, like the plain wall of early Hellenistic decoration, as representing space, the upper air;[326] it is rather the gallery wall of ancient Assyrian and early Hellenistic architecture. It is confined by an upper row of arched niches, each one, so far as can be determined in their ruined condition, placed within a rectangular frame of engaged columns and architrave, like the niches upon the outer fortification wall of the palace. And here we have the system that dominates Ctesiphon, the column and architrave framing arched niches. In the upper zone of the Ukhaiḍir façade symmetry has vanished. The long crowning row of niches calls attention to the fact that the decorated lower zones of the façade do not stand in the centre of the wall, and the doorways of the third zone bear no more relation to the arches below them than the perpendicular divisions of the Ctesiphon wall bear relation to one another. Another similarity exists between the two buildings. The arches of the second zone at Ukhaiḍir are decorated