ng small, but I can't see what it is."

"Whatever it may be," said the doctor, "it's running through the grass
in the direction we are going. Look at the grass yonder, it's waving as
something passes through."

But whatever it was they could not get a glimpse of it, though time
after time, when they felt that the game had either been passed or had
gone off to right or left, they saw the grass in motion again.

Then it stopped altogether, and the grass began to grow shorter before
them, the longer beds being down to their right where the land sloped
down, and they here and there caught the glint of water.

"Why, we must be following up the bed of an underground river," said
Bourne, "and this keeps breaking out from time to time, forming quite a
chain of little lakes. Yes, there, look; those must be ducks."

"Ducks they are," cried Griggs, as a little flock rose cackling from
somewhere away to their right and skimmed along over the top of some
waving reed-beds, but far out of shot.

"Another proof that we shall not starve," said the doctor, as they rode
slowly on, with the grass in places reaching to their saddle-bows.
"Let's strike away to the left here," he continued. "I fancy the ground
is drier. It is certainly wetter down to the right there, and the grass
longer."

He was quite right, for by bearing off a little they found at the end of
about half-a-mile that their progress had grown more and more easy, the
grass now only reaching to their stirrup-irons, while away further to
their left it was shorter still, looking quite lawn-like in the
distance.

"We're a good deal higher than we were at the camp, aren't we?" asked
Bourne.

"Certainly, and far-off as we are we certainly seem to be approaching
the mountain by a gradual slope."

"And that chain of pools and swamps is something of a river or stream
that comes down from one of the valleys yonder. Hallo! look out!"

Every one present had already been put on the _qui vive_ by a quick
rustling in front, followed by a loud whirring sound, as some
half-a-dozen birds, which they had evidently been driving before them
through the long grass in which they had kept out of sight, had now
found themselves too much exposed in the shorter herbage and taken
flight.

"Big partridges--monsters!" cried Chris excitedly.

"Yes," said the doctor dryly; "the most monstrous partridges I ever saw,
Chris. Why, they're turkeys, boy. They're making for those trees
yonde