consist of eocene sandstone and chalk. The Italian expedition under Antinori, which visited the shores of the Gulf of Cabes in 1875, also found that the sill was partially composed of rocky layers, and not merely of sand heaped up by the winds. The lowest point found by the expedition on the waterparting between the streams which run to the sea and those which flow westwards towards the sebkha, is over 170 feet above the sea-level. Since then, Roudaire, a French officer, has carefully prepared a detailed map of the whole region comprised between the Gulf of Cabes and the Algerian "shotts," and has definitely cleared up all uncertainties. The bar of Cabes still offers at its lowest elevation a height of over 150 feet; the sebkhas, which it separates from the Mediterranean, are themselves situated at a height of from 50 to 80 feet above the sea-level, and terminate westwards at another ridge more than 300 feet high. Beyond this point begin the depressions lying below the level of the Mediterranean. The total breadth of land required
to be excavated in order to connect the basin of the "shotts" with the Mediterranean would be over 100 miles.
The whole system of shotts and wadies — or, retaining the Arabie form, shtuts and widans — which may be called the "Tritonic" system, according to the hypotheses of most archæologists, was at one time probably a fluvial basin commencing at the source of the Igharghar. But this hydrographie system has long been broken up. The river bed is in many places blocked by danes, and the secondary depressions have been separated from it by ridges of upheaved rocks. That of the east especially, the largest of all, is bounded by hilly ridges which effect a junction with the southern Tunisian chains. From the ridge of Cubes to that of Kriz follow in succession north of the basin a series of abrupt cliffs, called the "Lips" (Esh-Sherb), as if the plain of the ancient lake was compared to an immense mouth. The sebkha, known at its cast end by the name of Shott-el-Fejej, at first is narrow, but gradually broadens out west wards; then, beyond a promontory on the southern
