The Khabour is a much more considerable river. It collects the waters which flow southward from at least two-thirds of the Mons Masius, and has, besides, an important source, which the Arabs regard as the true “head of the spring,” derived apparently from a spur of the Sinjar range. This stream, which rises about lat. 36° 40’, long. 40°, flows a little south of east to its junction near Koukab with the Jerujer or river Nisi-his, which comes down from Mons Masius with a course not much west of south. Both of these branches are formed by the union of a number of streams. Neither of them is fordable for some distance above their junction; and below it, they constitute a river of such magnitude as to be navigable for a considerable distance by steamers. The course of the Khabour below Koukab is tortuous; but its general direction is S.S.W. The entire length of the stream is certainly not less than 200 miles. The country between the “Mons Masius” and the Sinjar range is an undulating plain, from 60 to 70 miles in width, almost as devoid of geographical features as the alluvium of Babylonia. From a height the whole appears to be a dead level: but the traveller finds, on descending, that the surface, like that of the American prairies and the Roman Campagna, really rises and falls in a manner which offers a decided contrast to the alluvial flats nearer the sea. Great portions of the tract are very deficient in water. Only small streams descend from the Sinjar range, and these are soon absorbed by the thirsty soil; so that except in the immediate vicinity of the hills north and south, and along the courses of the Khabour, the Belik, and their affluents, there is little natural fertility, and cultivation is difficult. The soil too is often gypsiferous, and its salt and nitrous exudations destroy vegetation; while at the same time the streams and springs are from the same cause for the most part brackish and unpalatable. Volcanic action probably did not cease in the region very much, if at all, before the historical period. Fragments of basalt in many places strew the plain; and near the confluence of the two chief branches of the Khabour, not only are old craters of volcanoes distinctly visible, but a cone still rises from the centre of one, precisely like the cones in the craters of Etna and Vesuvius, composed entirely of loose lava, scorim, and ashes, and rising to the height of 300 feet. The name of this remarkable hill, which is Koukab, is even thought to imply that the volcano may have been active within the time to which the traditions of the country extend. [PLATE XXII., Fig. 2.]