Chap. XXX. 
THE EHINOCEEOS. 
611 
one part we have breccia of altered marl or slate in quartz, and 
various amygdaloids. It is curious to observe the different forms 
which silica assumes. We have it in claystone porphyry here, 
in minute round globules, no larger than turrdp-seed, dotted 
thickly over the matrix; or crystallised round the walls of cavities, 
once fiUed with air, or other elastic fluid; or it may appear in 
similar cavities as tufts of yellow asbestos, or as red, yellow, or 
gTeen crystals, or in laminae so arranged as to appear Hke fossil 
wood. Vungue forms the watershed between those sand rivulets 
which run to the N.E. and others which flow southward, as the 
Kapopo, Ue, and Due, which run into the Luia. 
We found that many elephants had been feeding on the fruit 
called Mokoronga. Tliis is a black-coloured plum, having purple 
juice. We all ate it in large quantities, as we found it delicious. 
The only defect it has, is the great size of the seed in comparison 
with the pulp. This is the chief fault of aU uncultivated wild 
fruits. The Mokoronga exists throughout this part of the country 
most abundantly, and the natives eagerly devour it, as it is said 
to be perfectly wholesome, or, as they express it, It is pure fat,” 
and fat is by them considered the best of food. Though only a 
little larger than a cherry, we found that the elephants had stood 
picking them off patiently by the hom\ We observed the foot¬ 
prints of a black rhinoceros {Rhinoceros hicornisy Linn.) and her calf. 
We saw other footprints among the hills of Semalembue, but the 
black rhinoceros is remarkably scarce in all the country north 
of the Zambesi. The white rhinoceros {^Rhinoceros simus of 
Burchell), or Mohohu of the Bechuanas, is quite extinct here, 
and will soon become unknown in the comitry to the south. It 
feeds almost entirely on grasses, and is of a timid unsuspecting 
disposition: this renders it an easy prey, and they are slaughtered 
without mercy on the introduction of fire-arms. The black pos¬ 
sesses a more savage nature, and, like the ill-natured in general, is 
never found with an ounce of fat in its body. From its greater 
fierceness and wariness, it holds its place in a district much longer 
than its more timid and better conditioned neighbour. Mr. Oswell 
was once stalking two of these beasts, and as they came slowly to 
him, he, Imowing that there is but little chance of hitting the 
small brain of this animal by a shot in the head, lay expecting 
one of them to give his shoulder^ tiU he was within a few yards. 
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