102 NOETH-WEST AFRICA. Physical Features. The mean altitude of Tunisia diminishes gradually from west to east, although the culminating points, ranging from 4,000 to o,000 feet, are distributed irregularly over the face of the land. One of the loftiest ridges occupies the north-west corner of the country towards the Algerian frontier, where it is disposed in the direction from south-west to north-east. To it may be given the name of "Khurair range," from the now historical group of tribes, who raise their crops of barley, maize, and tobacco in its upland glades. S#uth- westwards it is continued through the scarcely less elevated Ushtetta hills, and by those of the Beni Salah, which are limited southwards by the rugged gorges traversed by the Upper Mejerda in the department of Constantine. Most of their slopes are clothed with forests of leafy trees, and from many of the kefs, or summits, nothing is visible to the eye except a boundless sea of verdure. These hills are furrowed by a labyrinth of steep ravines and narrow glens watered by streamlets, which flow either south to the Mejerda, west to the Wed-el-Kebir, or north to the Mediterranean cirques. Here lofty headlands project far seawards, such as Cape Roux, whose abrupt escarpments and ruined forts mark the frontier between Tunis and Algeria. Farther west the Jebel Mermal develops another promontory, opposite Tabarka Island, which still bristles with Genoese fortifications, and which was formerly connected with the mainland by a dyke, now replaced by a tongue of sand flush with the water. East of the Khumir Mountains stretches the less elevated but still hilly district of Mogod, terminating north-west and north of Bizerta in several capes, such as the Ras-Dukkara, Ras-el-Kerun, Ras-Engela, Ras-el-Abiod, or " Cape White." These northernmost headlands of the African continent advance 20 geographical miles beyond the thirty- seventh parallel, thus approaching 90 miles nearer to the Pole than the point of Ceuta, opposite Gibraltar. Here the Tunisian waters are studded with a few islets and reefs, amongst which are the Fratelli, or " Brothers," known to the Romans as the Altars of Neptune. Further seawards, in a line with the Sorelle, or " Sisters," the island of Galita, over 1,000 feet high, and consisting of trachyte rocks analogous to the andesites of Ecuador and the blue porphyries of Esterel, can scarcely be geologically connected with the neighbouring mainland, from which it is separated by an abyss 170 fathoms deep. , Pliny asserts that the soil of Galita kills the scorpion, a fable still repeated in another form by mariners, who tell us that these volcanic rocks harbour no venomous reptile. The absence of snakes might serve as an additional proof that the island is not a detached fragment of the continent, although it has yielded some land shells of the same species as those found on the opposite coast. South of Mejerda, the region along the Algerian frontier presents no distinct orographic system. Broken into distinct sections by the AVed Melleg and its afflu- ents, the hills here follow the main line of the Atlas from south-west to north-east, leaving everywhere broad breaches mostly accessible to wheeled traffic. This region in fact forms the eastern prolongation of the upland steppes separating the two Algerian border ranges, which slope towards the Mediterranean and the Sahara
