XXXV.] CHANGES IN RIVER CHANNELS. 467 



wooded liills, flat-topped table-lands of sand, and broad marshes 

 bordering the streams. 



The channel of the riv^er is continually changing, and in a 

 year or two no trace remains of its former course. This is 

 owing to the growth of the semi -aquatic vegetation, which 

 quickly chokes up every space where the water does not flow 

 rapidly ; and this accounts for the fact that toward the end of 

 the dry season the actual channel is much smaller than in the 

 rains. 



If these swamps prove to be the modern representatives of 

 the old coal measures, we should find ferns, papyrus (especially 

 its roots) trees (some fallen on their sides and half rotten, others 

 still standing), and stumps and grasses, among the vegetable 

 fossils ; while those of the animal kingdom should include 

 skeletons of mud-fish and frogs, and also of an occasional croc- 

 odile, buffalo, or hippopotamus. Small thin sheets of sand 

 might perhaps indicate where the different channels had once 

 been. 



The country in Ussambi consisted mostly of flat-topped sand- 

 stone hills. Strata of red and yellow sandstone alternated, and 

 between them and the granite were usually masses of water- 

 worn pebbles. 



Uliinda is a thickly wooded country, with gentle undulations, 

 and occasional savannas or meadows watered by numberless 

 streams, most of them running northward to the Kongo. 



At its western side broad plains stretch right across Lovale. 

 They are light and sandy in the dry season, with belts of trees 

 along the different water-courses intersecting them, but during 

 the rains Ijecome quagmires and morasses. The water-shed be- 

 tween the Zambesi and Kongo basins lies along the centre of 

 these plains, which in the annual rainy season are waist-deep 

 in water, and the two basins then actually join. 



West of Lovale is the country of Kibokwe, where the rise out 

 of the central depression becomes very marked, and the country 

 is nearly all covered with forests. 



Bee-culture is here the chief occupation of the natives. The 

 large trees are utilized to support their bee-hives, the produce 

 of which forms a considerable and profitable item of barter. 

 They exchange the wax for all the foreign-trade goods they re- 



