for a bit, before changing into a
fly, which escapes from the hole in the skin it has eaten and flits away
to go and torture more animals."

"And not only horses, but other animals!" said West quietly.

"Horses only? Oh no; the bullocks get them terribly, and the various
kinds of antelopes as well. I've seen skins taken off blesboks and
wildebeestes full of holes. And there you are, my lad; that's a lecture
on natural history."

"Given in the queerest place and at the strangest time a lecture was
ever given anywhere," said West.

"It is very horrible, though, for the animals to be tortured so!"

"Yes," said Ingleborough thoughtfully; "but the flies must enjoy
themselves wonderfully. They must have what people in England call a
high old time, and--eh? What's the matter?"

"Be ready!" whispered West. "Someone coming; there's no mistake now!"

CHAPTER TWENTY FOUR.

A REAL ALARM.

Ingleborough drew in his breath with a hiss, and once more stood on his
guard with his comrade right in the darkness, and in front of the two
ponies, where a good view of the stream outside and the corner rock
fringed with ferns could be obtained.

For voices could be heard as of two men talking together, while plash,
plash, plash their footsteps in the water echoed for some moments from
the rocky sides of the chasm, before they came leisurely into sight
round the corner and stood knee-deep looking straight into the cave,
little thinking of the peril in which they were, for a couple of rifles
covered them, and the slightest pressure upon the triggers would have
sent the long thin bullets upon their errand to pierce the Boers through
and through.

But no pressure came, those within the cavern seeing clearly enough from
the men's careless manner that they felt perfectly safe and were upon no
unusual errand.

They were roughly enough clad, and their outer garments showed that they
had been slept in for some time and exposed to all kinds of weather; but
there was something about their mien, and more in the words they let
fall, which showed them to belong to a superior type of Boer.

"Yes, there it is," said one of the two in Boer-Dutch, "just as it was
ten years ago when I was here on a hunting trip. The source is
perennial, and beautiful water. That's why I wanted Dietz to come out
of our way."

"Does it go in far?"

"About a hundred yards, and there the water suddenly gushes out of the
floor; but there are some nasty