OP THE HALOLIMNIC FAUNA OF LAKE TANGANYIKA. 



355 



FIG. 1. 



-PLAN OF THE GRABEN SYSTEM AND ITS RELATION TO THE 

 CONGO BASIN. 



Eastern Arm. 

 1. Lake Stefanie. 



Eudolf. 



Baringo. 



Navaisha^ 



Natron. 



Manyora. 



Western Arm. 



7. Lake Albert. 



8. „ Albert Edward. 



9. „ Kivu. 



10. „ Tanganyika. 



11. ,, Rukwa. 



12. Lake Nyassa. 



in this cas8 are : (1) The existence of volcanic action within 

 the containing walls of the great western Graben. (2) The 

 fact that volcanic action is not extinct in this region, though it 



B 2 



