Such are the chief points of interest connected with the two great Mesopotamian rivers.  These form, as has been already observed, the only marked and striking characteristics of the country, which, except for them, and for one further feature, which now requires notice, would be absolutely unvaried and uniform.  On the Arabian side of the Euphrates, 50 miles south of the ruins of Babylon, and 25 or 30 miles from the river, is a fresh-water lake of very considerable dimensions—­the Bahr-i-Nedjif, the “Assyrium stagnum” of Justin.  This is a natural basin, 40 miles long, and from 10 to 20 miles broad, enclosed on three sides by sandstone cliffs, varying from 20 to 200 feet in height, and shut in on the fourth side—­the north-east—­by a rocky ridge, which intervenes between the valley of the Euphrates and this inland sea.  The cliffs are water-worn, presenting distinct indications of more than one level at which the water has rested in former times.  At the season of the inundation this lake is liable to be confounded with the extensive floods and marshes which extend continuously from the country west of the Birs Nimrud to Samava.  But at other tines the distinction between the Bahr and the marshes is very evident, the former remaining when the latter disappear altogether, and not diminishing very greatly in size even in the driest season.  The water of the lake is fresh and sweet, so long as it communicates with the Euphrates; when the communication is cut off it becomes very unpalatable, and those who dwell in the vicinity are no longer able to drink it.  This result is attributed to the connection of the lake with rocks of the gypsiferous series.

It is obvious that the only natural divisions of Chaldaea a proper are those made by the river-courses.  The principal tract must always have been that which intervenes between the two streams.  This was anciently a district some 300 miles in length, varying from 20 to 100 miles in breadth, and perhaps averaging 50 miles, which must thus have contained an area of about 15,000 square miles.  The tract between the Euphrates and Arabia was at all times smaller than this, and in the most flourishing period of Chaldaea must have fallen short of 10,000 square miles.

We have no evidence that the natural division of Chaldaea here indicated was ever employed in ancient times for political purposes.  The division which appears to have been so employed was one into northern and southern Chaldaea, the first extending from Hit to a little below Babylon, the second from Niffer to the shores of the Persian Gulf.  In each of these districts we have a sort of tetrarchy, or special pre-eminence of four cities, such as appears to be indicated by the words—­“The beginning of his kingdom was Babel, and Erech, and Accad and Calneh, in the land of Shinar.”  The southern tetrarchy is composed of the four cities, Ur or Hur, Huruk, Nipur, and Larsa or Larancha, which are probably identified