workmanship, wherein it is natural to expect a closer adherence to local tradition; but it is important to point out how close that adherence is, and how well it corresponds with recorded examples of Mesopotamian and Persian decoration earlier than the Umayyads, whereas the decoration in the same regions, but at a later period, diverges widely from the older schemes. The divergence is due, in my estimation, to the diffusion of Western influence when the western and the eastern provinces of the khalifate were drawn together under the Abbâsids and all quarters of their empire contributed to their constructions. In the ninth century we find Mesopotamian architecture in Cairo and Coptic decoration in Sâmarrâ. I regard the oriental character of Ukhaiḍir as indicative not only of its isolated position, beyond the direct course of international civilization and arts, but also as typical of the primitive age during which it arose. Materials for the study of early Mohammadan decoration are still so scanty that the difficulty of assigning exact dates to such as we possess is great. It is enhanced by the fact that the workmen of the first khalifs must have been of non-Arab extraction. The Arab invaders, pouring in out of deserts which were innocent of monumental constructions, had nothing to contribute to architecture or to the arts. So far as we know them in the pre-Mohammadan period they had not created an art of their own. Along the trade-routes, the rock-cut tombs of Madâin Ṣâliḥ and of Petra exhibit, without salient divergence, the artistic principles of Hellenized Egypt and Hellenized Syria, while concerning the older Arab civilizations in the southern parts of the peninsula we have as yet no evidence save that of inscriptions. The Mohammadan conquerors employed the workmen of their predecessors, and according to the nature of their own traditions, these workmen might raise a palace with a basilical hall, like Mshattâ, or a palace entirely composed of lîwân groups like Ukhaiḍir; they might cover their walls with Hellenistic fresco, as at Qṣair ‘Amrah, or with ornament derived mainly from the ancient East, as again at Ukhaiḍir. The variations of this period were due to individual idiosyncrasy, or rather to individual training; there is no reason why they should be taken to denote a chronological distinction. A hundred and fifty years later this heterogeneous material had been welded together and the Islâmic _Weltkunst_ was beginning to take shape. Sâmarrâ, in the eastern part of the Abbâsid dominions, the mosque of Ibn Ṭulûn in the western part, re-echo one another; artistic conceptions are not only interchangeable, they are the same; and though, all through the history of the arts of Islâm, local peculiarities, based on local conditions and traditions, continue to differentiate one region from another, it is not the differences but the similarities which are the most striking. They go hand in hand with the singular solidarity of Islâm, with the