oning tone.

The man smiled pleasantly, and the boy repeated his question; but it was
plain that the black did not understand.

"Oomph! Oomph! Oomph!" growled Mark, in as near an imitation of the
monarch of the forest's roar as he could contrive after a couple of
visits to the Zoo; but it had no effect whatever on their surroundings
till the black, who now fully grasped his meaning, crouched down and
uttered a startling, barking roar which made two or three of the nearest
bullocks start up and stare in their direction.

"Here, you, sir, stop that!" shouted Buck Denham, the driver of their
waggon, the first being in charge of the Hottentot.

The black turned to him, smiling, and nodded, before meeting the boys'
eyes again and shaking his head.

Just then the doctor approached, to ask the reason of their guide's
imitation.

"Oh," he said, on being informed, "don't encourage him in anything of
that sort again, or we shall have a stampede of the ponies and bullocks.
Well, Mark, recollect that it's your first watch to-night."

"Oh, I shan't forget," was the reply. "But you don't think we have come
out far enough yet to meet with dangerous wild beasts, do you?"

"Oh, indeed, but I do," replied the doctor. "We have left the last post
of civilisation behind, and we may come upon danger at any time. Of
course you will mount guard with one of the double rifles charged with
bullet, and if there really is any suggestion of danger you will fire,
so as to give the alarm. We shall come to your help directly."

"Oh, yes, I understand," said Mark confidently, and he passed the
intervening time before he received his orders going round their little
camp with his cousin, watching the final preparations made by the
drivers and forelopers, a couple of ordinary thick-lipped blacks, and
then having a chat with the two keepers about what a change it was from
the park and grounds of the old manor.

As the time approached, Mark, in spite of his assumed cheerfulness,
could not master a slight feeling of discomfort. It was evidently going
to be a cool, dark night. The very sound of it was startling to the
lad--the announcement that he was to keep the full watch over their
little camp of two waggons in a country where lions were common, and on
one of the banks of the river which might very well be haunted by
hippopotami and loathsome crocodiles.

The captain had spoken of its being called Reptile River, and of course
that was w