irection--there is no north, no south, no east, no west.
UP is about the only direction which is well defined, and that, of
course, is DOWN to you of the outer crust. Since the sun neither rises
nor sets there is no method of indicating direction beyond visible
objects such as high mountains, forests, lakes, and seas.

The plain which lies beyond the white cliffs which flank the Darel Az
upon the shore nearest the Mountains of the Clouds is about as near to
any direction as any Pellucidarian can come. If you happen not to have
heard of the Darel Az, or the white cliffs, or the Mountains of the
Clouds you feel that there is something lacking, and long for the good
old understandable northeast and southwest of the outer world.

We had barely entered the great plain when we discovered two enormous
animals approaching us from a great distance. So far were they that we
could not distinguish what manner of beasts they might be, but as they
came closer, I saw that they were enormous quadrupeds, eighty or a
hundred feet long, with tiny heads perched at the top of very long
necks. Their heads must have been quite forty feet from the ground.
The beasts moved very slowly--that is their action was slow--but their
strides covered such a great distance that in reality they traveled
considerably faster than a man walks.

As they drew still nearer we discovered that upon the back of each sat
a human being. Then Dian knew what they were, though she never before
had seen one.

"They are lidis from the land of the Thorians," she cried. "Thoria
lies at the outer verge of the Land of Awful Shadow. The Thorians
alone of all the races of Pellucidar ride the lidi, for nowhere else
than beside the dark country are they found."

"What is the Land of Awful Shadow?" I asked.

"It is the land which lies beneath the Dead World," replied Dian; "the
Dead World which hangs forever between the sun and Pellucidar above the
Land of Awful Shadow. It is the Dead World which makes the great
shadow upon this portion of Pellucidar."

I did not fully understand what she meant, nor am I sure that I do yet,
for I have never been to that part of Pellucidar from which the Dead
World is visible; but Perry says that it is the moon of Pellucidar--a
tiny planet within a planet--and that it revolves around the earth's
axis coincidently with the earth, and thus is always above the same
spot within Pellucidar.

I remember that Perry was very much excited