be said to actually mark the limes. Gemellae section: runs for about parallel to and south of the Wad Jadi, south and southwest of the Roman city of Vescera (modern Biskra); a major Roman military establishment (Gemellae) is at the center. The fossatum is close to, but slightly north of, the border in the Roman administrative district known as the limes Gemellensis. It marks the end of the irrigable area (with the Wad Jadi as source) and beginning of the Sahara desert. Ad Majores section: begins at Ad Majores (modern Besseriani) and runs eastwards for about , following a range of hills, and almost reaching the modern village of Matlawi. The fossatum is associated with the Roman administrative border district known as the limes Montensis, but as it is or more away from the known border it cannot be said to actually mark the limes. However, a more recent examination has shown that the "fossatum" is probably a Roman road, not a ditch. There may also be a further segment north of Tobna. Generally the Fossatum consists of a ditch and earth embankments on either side using the material from the ditch. Sometimes the embankments are supplemented by dry stone walls on one or both sides; rarely, there are stone walls without a ditch. The width of the Fossatum is generally but in exceptional cases may be as much as . Wherever possible, it or its highest wall is constructed on the counterscarp. Excavations near Gemellae showed the depth there to be , with a width of at the bottom widening to at the top. The Fossatum is accompanied by many small watchtowers and numerous forts, often built within sight of one another. There are similar, but shorter, fossata in other parts of North Africa. Between the Matmata and Tabaga ranges in modern Tunisia there is a fossatum which was duplicated during World War II. There also appears to be a fossatum at Bou Regreg in Morocco although this would not have been within the scope of the proclamation of the Codex Theodosianus because at that time the province was not in Africa, administratively speaking. See also Limes Tripolitanus Limes Mauretaniae Notes Bibliography Baradez, J (1949). Fossatum Africae. Recherches Aériennes sur l'organisation des confins Sahariens a l'Epoque Romaine. Arts et Métiers Graphiques, Paris. Basset, R. (1905). "La légende de Bent el Khass", Revue Africaine v. 49 p. 18-34. Gsell, S.