86 
THE TANGANYIKA TROT LEM. 
the series abut abruptly up against the western wall of the 
great valley in which Kivu lies to the south, and these two 
western cones are quite distinct in character from any of 
those to the east. They are both, at present, fully active, 
and both present the squat, truncated form of a volcano in 
the first phase of its activity. The rim of the immense 
crater of the more southern mountain, Kirungo-cha-Gongo, 
we found to be 1 1,350 feet above the level of the sea, and 
the mountain to the north-west, Kirungo-cha-Moto, is a 
little lower. 
The whole appearance of these, the Mfumbiro Mountains, 
is magnificent and impressive in the extreme. And although 
they contain no individual eminence, anything like so high 
as Kilima-Njaro, they form a still vigorously active volcanic 
massif, which is vastly more imposing and extensive than 
either Kenia, Kilima-Njaro, or Elgon. 
As has been said, the walls of the valley containing Lake 
Kivu to the south, are not really interrupted by the volcanic 
dam, they pass its slopes to the east and the west, and 
again enclose the central eurycolpic fold immediately to 
the north of the transverse line of cones. Having passed 
over the mountains, we see, in fact, that their northern 
slopes sweep away into the floor of the depression many 
miles, and the volcanic ash and lava-streams are found, 
finally, to run out upon the alluvial plains which bound the 
southern shore of the Albert Edward Nyanza. The alluvial 
substance of these plains runs, in fact, actually back again 
southwards underneath the more modern volcanic matter 
which has been piled upon them ; and there are several 
facts connected with their character and structure that are 
of the utmost importance, when we come to interpret the 
phenomena which this highly peculiar district presents. 
The fauna of Lake Kivu is, as I have described in 
