OF THE HALOLIMNIC FAUNA OF LAKE TANGANYIKA. 



317 



features, to a certain extent, resemble those of the peculiar 

 mountain plateau-region which is characteristic of Equatorial 

 East Africa. Isolated volcanoes, now extinct, such as Elgon, 

 Kenya and Kilima-Njaro rise to heights, in the two latter cases, 

 of over 18,000 feet, but the most characteristic feature is the 

 double chain of depressions which contain the numerous 

 longitudinal lakes of Equatorial Africa. This system, which 

 may be said to commence with Lake Eudolf, just south of 

 Abyssinia, bifurcates, the eastern and smaller arm containing 

 such lakes as Baringo (3,200 feet), and Navaisha (6,200 feet), 

 wdiilst the western, or more important arm, includes the 

 up23ermost Nile-valley and such lakes as the Albert Nyanza 

 (2,300 feet), the Albert Edward (3,240 feet), and Kivu (4,900 

 feet). This latter lake, as Mr. Moore has shown, formerly 

 belonged to the Nile-valley system, but owing to volcanic 

 extravasations the drainage has been reversed and its waters 

 now find their way into Lake Tanganyika (2,700 feet). The 

 two arms of this double series of longitudinal depressions are 

 regarded as to a certain extent coalescing in the great lake of 

 Nyassa (1,500 feet), where the system of these peculiar 

 longitudinal depressions may be said to terminate. The 

 mountain system of East Africa, in another form, is renewed 

 in the Drakensberg, where the surveyors have lately found 

 numerous indications of volcanic action. A sketch-map of the 

 East African Lake-Chain (after Suess), modified from Gregory's 

 The Great Pdft Vallaj, is appended. (Fig. 1.) 



Between the two arms of the system of longitudinal 

 depressions (" Graben " of Suess) is situated the wide basin of the 

 Victoria Nyanza (3,900 feet), which has an area in miles of 

 270 X 225 — a veritable inland sea. This constitutes a sort of 

 broad and shallow depression in complete contrast to the 

 Graben with their vertical walls and succession of trough 

 faults. 



Our brief sketch of the Great Central East African Eange 

 would not be complete without allusion to two very remarkable 

 features in connection therewith, which characterize the 

 uppermost Nile-valley system in the neighbourhood of the Lake 

 Albert Edward. The first of these is the still active volcanic 

 range of Mount M'fumbiro, which crosses the great western arm 

 of the Graben system at a right angle, and rises to a height of 

 14,000 feet in Karisimbi (extinct), whilst the rim of the 

 crater of the still active Kirungo-cha-Gongo Mr. Moore found 

 to be 11,350 feet. As lie observes, this mass acts like a dam to 

 the original drainage of the Graben. The chief points to note 



