balance it had
ever had. Its dimly functioning brain, probably no larger than a
walnut in that gigantic skull, ceased more and more to guide it.

With a rasping scream that set the Earthmen's teeth on edge, it
charged for the wall on Dex's side. Dex just managed to swerve it with
a blast from the tube so prolonged that half its great lower jaw fell
away.

At this the titanic thing went wholly, colossally mad! It whirled
toward Brand, jerking around again as a searing on that side jarred
its dull sensory nerves, then headed at last straight toward the stone
wall of the dome building.

With the rays from both tubes flicking it like monstrous spurs, it
charged insanely toward the bulge of the circular wall. With all its
tons and tons of weight it crashed against the stonework. There was a
thunderous crackling noise, and the wall sagged in perceptibly, while
the metal roof bent to accommodate the new curvature of its supporting
beams.

The monstrous lizard, jerked off its huge legs by the impact,
staggered up and retreated toward the two men. But again the maddening
pain in its hindquarters sent it careening toward the building wall.
This time it raised high up on its hind legs in a blind effort to
climb over it. "God, it must be five stories tall!" ejaculated Brand.
Thunderingly its forelegs came down on the edge of the roof.

* * * * *

There was another deafening crash of stone and shrieking of torn
metal. Just under the cornice, the wall sagged away from the roof and
the top rows of heavy stone blocks slithered inward.

"Again!" shouted Brand.

His tube was pointing almost continuously now at the metal door
leading from the dome building. The Rogans inside, at the shocks that
were battering down a section of their great building, were all trying
to get out to the yard at once. In a stream they rushed for the
doorway. And in loathsome heaps they fell at the impact of the ray
and shriveled to nothingness on the bombarded threshold.

"Once more--" Brand repeated, his voice hoarse and tense.

And as though the monster heard and understood, it rushed again with
all its vast weight and force against the wall in a mad effort to
escape the things that were blasting the living flesh from its
colossal framework.

This charge was the last. With a roaring crash a section of the
building thirty yards across went back and down, leaving the massive
roof to sag threateningly on its battere