n summer days which we sometimes have in
late autumn. Everybody enjoyed each day as it came, and thought little
about the coming cold. But one morning the sky was gray and gloomy,
and the sun could not pierce through the heavy clouds. The air was
cold and now and then a snowflake was falling.

There was no meat at the cave, and everybody was hungry. So Bighorn
said to the men, "Let's hunt the bison to-day."

The men crowded around, for they were always glad to go hunting with
Bighorn. As soon as he had shown them his plan, they took their
weapons and started toward the herd.

Bighorn expected to find the herd feeding quietly on a hillside. But,
instead, the bison were tossing their horns, sniffing the air, and
looking this way and that.

Bighorn saw that the bison were restless and that he could not take
them by surprise. "We shall have a hard chase," said he to the men,
"if we get a bison to-day."

The men stood still for a moment, for they did not know what to do.
Fine snowflakes were now falling and the dark clouds threatened a
heavy storm. But the men were hungry and they were not ready to give
up the hunt at once.

"Listen!" said Bighorn, as a low rumbling sound came from the upper
valley.

The Cave-men put their ears to the ground and heard a sound like
distant thunder. As they listened it came nearer and nearer and the
ground seemed to shake.

The Cave-men were not afraid. They knew what the sound meant. The
bison, too, knew what it meant. They knew that winter was coming, and
that it was time for them to be gone. They knew that the laggard herds
were racing with the storm.

And so the sentinels of the scattered herds gave signals to the bison.
And before the Cave-men were on their feet, the bison had started
toward the ford.

Louder and louder the rumbling sound grew as the great herd galloped
on. The snow was now falling thick and fast, and a cold northwest wind
was blowing. But in spite of the wind and the snow, the Cave-men
pressed on toward the ford. Bighorn still hoped to get a bison as the
great herd passed.

By the time the herd reached the ford, the wind had become a strong
gale. The air was so thick with the snow that it nearly blinded the
men. Then Bighorn turned and said to the men, "We must find a shelter
from the storm."

The bison, too, tried to find a shelter. Some of them hugged up
closely to the sheltered side of the cliffs. Others sought cover in
the ravines. But many could fi