TIGRIS (Greek, from the old Persian tigra, an arrow). One of the two large rivers which inclose the historic region of 'Mesopotamia. in Asiatic Turkey (Map: Turkey in Asia. M 6). It rises by two main headetreams in the moun tains of Kurdistan, near the Euphrates. Thence it flows in a winding southeast course of about 950 miles till it joins the Euphrates at Kona to form the Shat-el-Arab, which after a short course flows into the Persian Gulf. The Tigris is a rapid and turbid stream. In its upper course it re ceives numerous tributaries from both sides. Be low Mosul, however, the tributaries come nearly all from the east, the region between the Lignis and the Euphrates being here a desert overgrown with wormwood and similar scrub. Farther down the Tigris communicates across the desert with the Euphrates by a number of bayous or canals, some of which are dry the greater part of the year. At the confluence the Tigris. though
shorter than the Euphrates, is more voluminous, and it is navigable for steamers to Bagdad. Thence smaller vessels proceed to Mosul, and above that city rafts descend from Diarbekir, almost at the source of the river. The rafts, however, are broken up at Mosul and trans ported back by camel. The main tributary of the Tigris is the Diyala, which joins it from the east, a short distance below Bagdad, and which is navigable for some distance by small vessels. Next to the Diyala, the largest affluent is the Greater Zab. Outside of the three cities men tioned the banks of the Tigris are very thinly populated. Among the remains of ancient cities on the banks of the Tigris are those of Nineveh. Selencia, and Ctesiphon.