now in June?" questioned Stacy.

"You must remember that you are a good many thousand feet up," the
Professor informed him.

"Up? I thought I was down in a crater."

"You are both up and down," spoke up Tad.

"Yes, I'm usually up and down, first standing on my feet then on my
head," retorted Stacy. "How are we going to sleep?"

"Same as usual. Pick out your beds, then roll up in your blankets,"
directed Dad. "You are used to it, eh?"

"Well," drawled Chunky, "I've slept in a good many different kinds of
beds, but this is the first time I ever slept in a lava bed."

True to Dad's prophecy, the snow came within half an hour.

"Better turn in before the beds get too wet," advised Dad.

All hands turned in. Sleep did not come to the boys as readily as usual.
They had been sleeping in real beds too long. After a time the snow
changed to rain in the warmth of the crater. Chunky got up disgustedly.

"I'm tired of sleeping in the bath tub," he declared. "Think I'll move
into the hall bedroom."

Chuckles were heard from beneath other blankets, while Stacy, grumbling
and growling, fussed about until he found a place that appeared to be
to his liking.

"When you get through changing beds perhaps you will give us a chance
to go to sleep," called the guide.

Stacy's voice died away to an indistinct murmur. Soon after that quiet
settled over the dark hole in the mountain. The rain came down harder
than ever, but by this time the Pony Rider Boys were asleep. They
neither heard nor felt the water, though every one was drenched to the
skin.

Toward morning Tad woke up with a start. He thought something had
startled him. Just then an unearthly yell woke the echoes of the
crater. Yell upon yell followed for the next few seconds, each yell
seeming to be further away than the preceding one, and finally dying
out altogether.

"It's Chunky!" shouted Tad, kicking himself free of his blankets and
leaping up. "Some thing's happened to Chunky!"

CHAPTER V

TAD LENDS HELPING HAND

"What is it? What is it?" cried the other boys, getting free of their
blankets and in the confusion rolling and kicking about in the cinders.

"What is it?" shouted the Professor, very much excited.

Ned, dragging his blanket after him, had started to run about, not
knowing which way to turn nor what had occurred. In the meantime the
guide and Tad had started in the direction from which the yells had
seemed to come.

"