frill, while again others were dotted
with hideous spikes and prickles, all being given to turn defiantly upon
the intruders to their domain, and menacingly open their gaping mouths,
lined with orange, yellow, or rich blue; but ready to take flight all
the same and plunge into the rock rift or hole which made their home.

At last there was a rocky slope to climb, up to the left of which a
sugar-loaf peak rose, which Carey at once concluded was the one which
the doctor had climbed; so, feeling that their task was pretty well
achieved, he manfully breasted the rock-strewn slope, ignored the
lizards basking in the sun, and directly after gave a shout of
satisfaction, for on one side there came a deliciously cool breeze,
while on the other he was looking down at a vividly blue lake lying in a
hollow a couple of hundred feet below where he stood, and quite
sheltered from the wind, so that its surface was like a mirror and
reflected the hills all round.

"Lovely, eh, Carey?"

"It is glorious," panted the boy. "Isn't it fine, Bob?"

Bostock grunted, laid down his gun, swung round the satchel containing
the food, and passed the strap over his head, setting it afterwards on
the ground in a very significant manner.

"Yes," said the doctor; "we may as well have our lunch."

"But I say," said Carey, "do you really think this was once a volcano,
doctor?"

"Certainly, and the blue water we look down upon was preceded by a lake
of fire."

"But how was that? Where did the water come from? Not from the sea."

"No, from the draining of these hills or mountains all round, upon which
you have seen the clouds gather and melt into rain."

"And that put out the volcanic fire?" said Carey, quickly.

"Oh, no," replied the doctor, smiling. "If those trickling streams had
run down into a lake of fire they would have flown up again in steam
with tremendous explosions. This lake of water did not form until the
volcano was quite extinct, and--"

"Shall I cut up the wittles, sir?" said Bostock, who had been
impatiently waiting for the doctor to end his lecture.

"Here, fall to, Carey; Bostock is getting ravenous." And they ate their
lunch, with Carey longing to go down the inner slope to examine the lake
for fish and try to find out how deep it was.

It was a double feast, one for the body and one for the brain, the long
walk and exertion having made all hungry, and as soon as this was
appeased the doctor led the way for the f