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                            THE GREEN WORLD

                            BY HAL CLEMENT

                     The planet was an enigma--and
                        its solution was death!

           [Transcriber's Note: This etext was produced from
                Worlds of If Science Fiction, May 1963.
         Extensive research did not uncover any evidence that
         the U.S. copyright on this publication was renewed.]


                                   I

A zoo can be a rather depressing place, or it can be a lot of fun, or
it can be so dull as to make the mind wander elsewhere in self-defense.
In fairness to Emeraude, Robin Lampert had to concede that this one was
not quite in the last group. He had been able to keep his attention on
the exhibits. This was, in a way, surprising; for while a frontier town
has a perfect right to construct and maintain a zoo if it wishes, one
can hardly expect such a place to do a very good job.

The present example was, it must be admitted, not too good. The
exhibits were in fairly ordinary cages--barred for the larger
creatures, glassed for the smaller ones. No particular attempt had been
made to imitate natural surroundings. The place looked as artificial as
bare concrete and iron could make it. To a person used to the luxuries
provided their captive animals by the great cities of Earth and her
sister planets, the environment might have been a gloomy one.

Lampert did not feel that way. He had no particular standards of what
a zoo should be, and he would probably have considered attempts at
reproduction of natural habitat a distracting waste of time. He was not
a biologist, and had only one reason for visiting the Emeraude zoo; the
guide had insisted upon it.

There was, of course, some justice in the demand. A man who was taking
on the responsibility of caring for Lampert and his friends in the
jungles of Viridis had a right to require that his charges know what
they were facing. Lampert wanted to know, himself; so he had read
conscientiously every placard on every cage he had been able to find.
These had not been particularly informative, except in one or two
cases. Most of the facts had been obvious from a look at the cages'
inhabitants. Even a geophysicist could tell that the _Felodon_, for
example, was carnivorous--after one of the creatures had bared a rather
startling set of fangs by yawning in his face. The placard had told
little more. Less, in fact, than McLaughlin had already said about the
beasts.

On the other hand, it had been distinctly informative to read that a
small, salamanderlike thing in one of the glass-fronted cages was as
poisonous as the most dangerous of Terrestrial snakes. There had been
nothing in _its_ appearance to betray the fact. It was at this point,
in fact, that Lampert began really to awaken to what he was doing.

       *       *       *       *       *

He was aroused all the way by McLaughlin's explanation of a number
which appeared on a good many of the placards. Lampert had noticed
it already. The number was always, it seemed, different, though
always in the same place, and bore signs of much repainting. It bore
no relationship to any classification scheme that Lampert knew, and
neither of the paleontologists could enlighten him. Eventually he
turned to McLaughlin and asked--not expecting a useful answer, since
the man was a guide rather than a naturalist. However, the tall man
gave a faint smile and replied without hesitation.

"That's just the number of human deaths known to have been caused by
that animal this year." It did not comfort Lampert too greatly to learn
that the year used was that of Viridis, some seventeen times as long as
that of Earth. For the _Felodon_ the number stood at twelve. This was
not very much when compared to the annual losses from tigers in India
during the nineteenth century. But this reflection was not particularly
consoling. The human population of Viridis was so very small compared
to that of India.

Lampert examined the creature thoughtfully. It was of moderate size
as carnivores went--some four feet long without the tail--and looked
rather harmless as long as it kept its mouth shut. It was lying in the
center of the cage, so it was difficult to judge the length of its
legs. It showed no trace of the tendency displayed by many captive
animals, of lying against a wall or in a corner when relaxed; and there
was none of the restless pacing so characteristic of Earth's big cats
under similar circumstances. It simply lay and stared back at Lampert,
so steadily that he never was sure whether or not the cold eyes were
provided with lids.

"I never liked reptiles back home, but I think I like these creatures
less." The voice of Mitsuitei, the little archaeologist, cut into
Lampert's reverie.

"Don't let Hans or Ndomi hear you mention them in the same breath with
reptiles," he answered.

"Well, I'm not fond of frogs, either."

"I'm afraid that wouldn't make them much happier. These are not even
amphibians."

"They certainly are. I've been told that they lay eggs in water and
have a tadpole stage--"

"I should have said they aren't Amphibians with a capital A. That is,
they don't belong to the order Amphibia, since they are not genetically
related to the corresponding order on Earth, as far as we know.
Sulewayo gets quite peeved at people who try to lump terrestrial and
extraterrestrial creatures in the same order. I believe that whoever
decides things for biologists has decreed that on Viridis the dominant
order is to be called Amphibids. It's a quibble, if you like. But I can
see why they insist on it."

"Mph. So can I. Even now you sometimes run into people who go to great
length to make you admit that there are pyramids both in Egypt and
Mexico--and for that matter on Regulus Six--and infer from that that
their makers had something in the way of common culture. I say these
things are amphibians, without the Capital A, because they are at home
both on land and in water. And a dictionary would back me up. I don't
insist that they're related to those of Earth--any more than a Mayan
pyramid has anything but geometry in common with an Egyptian one."

"But I've heard--"

"I'm sure you have, but it's a sore subject. I'll be open-minded if
you like and admit that some Egyptian _may_ have been blown across the
Atlantic and taught architecture to the Americans, but I don't regard
it as proved. What was that remark of yours--'as far as we know'--in
connection with the ancestry of the amphibids? That's being at least as
open-minded as I was, I would say."

       *       *       *       *       *

"In a way, yes. I don't think anyone has seriously suggested that these
things originated on Earth. However, a puzzle we're here to investigate
still exists. How there could be life forms corresponding to those
which took a good half billion years to evolve elsewhere, on a planet
which by geophysical evidence hasn't been solid for forty million?
_Someone_ certainly has suggested that the world was stocked from
outside. But certainly it hasn't been proved. I don't think anyone has
tried very hard, either. And I certainly won't, on a planet with as
much radioactivity as this one."

"You think that would account for high-speed evolution?"

Lampert shrugged his shoulders, and began to stroll toward the next
cage. "Ask the paleontologists. My opinion doesn't carry much weight."

Mitsuitei nodded, started to follow the geophysicist, and then turned
back to stare once more at the carnivore lying a few feet away. It
stared back unblinkingly.

The visit to the zoo was one of several, which continued until Lampert,
Mitsuitei and the two paleontologists were able to identify each of a
dozen animals which were most concerned in the death rate of Viridis.
Apparently McLaughlin was not the only guide who did this. The zoo was
equipped to give a "final examination" in which any creature the guide
desired could be seen on a television screen from viewpoints quite
different from those obtained in front of the cages. McLaughlin proved
hard to satisfy.

Lampert did not blame him. He knew a lot about Viridis, of course. He
had not only read of it in ordinary reference material, but had done
much of the laboratory work on drill cores brought from the planet. His
name had been one of those attached to the report giving the probable
age of the planet's crust. At that time, however, the mental picture
he held had been of continent distribution, rock strata, zones of
diastrophic stress and the like. The question of the appearance, or
even the existence, of plants, animals and people had simply never
risen to conscious level in his mind.

That had changed, shortly before his arrival. The tramp spacer which
had brought him and his group to Viridis had had to orbit about the
world in free fall for several hours while its obsolete drive elements
"cooled," and the passengers had examined the planet.

Lampert, oddly enough, had been as much impressed by the night side
as by the sunlit hemisphere. The latter had shown, at twenty thousand
kilometers, a fairly standard land and water pattern. The most
unusual thing about it had been the almost perfect uniformity of the
land coloration, a light green which bespoke, or at least implied, a
virtually complete covering of vegetation.

By the time the ship had circled to the dark side, however, it was much
closer to the surface; and Lampert would have expected to make out
luminous sparks and patches of towns and cities by the hundreds.

He saw just two, and was not really sure of those. For the rest,
the planet was a vast, gray-black circle occulting a portion of
the Milky Way. It was not absolutely black, either. Its contrast
with the background of the galaxy was diminished by the glow in the
upper atmosphere arising from the recombination of water molecules
dissociated during the day by Beta Librae's fierce ultraviolet light.
The center of the circle was darker than the edges, where the line of
sight penetrated through more of the luminous gas.

But even this sight, unusual as it was, did not affect Lampert as
much as the lack of city lights. He had done field work in lonely,
wild places before, of course; but until now he had always had the
feeling of being in an island of wilderness more or less surrounded by
civilization. On Viridis it was the civilized spots which formed the
islands. And very small islands they were. There was no known native
intelligent race, and settlements of alien races such as the men from
Earth were still few and far between.

So Lampert was prepared for McLaughlin's care in readying the group for
its trip. He was even glad of it, though he would probably not have
admitted to being at all afraid of the venture. He would simply have
said that it was nice to have a guide who took his responsibilities
seriously.

       *       *       *       *       *

That of course, did not mean that Lampert was intending to disavow any
of his own responsibilities. He, like McLaughlin, had been keeping a
careful eye on the other members of the group, looking for the signs of
impatience or ill temper which could be the seeds of serious trouble
if the journey were prolonged. He had come to tentative conclusions
about this during the flight from Earth, but was pleased to see that,
apparently, men who could stand the enforced companionship of a tramp
spacer were also able to retain their senses of humor in the steam-bath
environment of Viridis.

Sulewayo, of course, had seemed safe from the first. A man who has
spent his formative years in the Congo rain forests where his ancestors
had lived for generations was ideal for this world. His sense of humor
was extremely durable. Lampert suspected that it might sometimes be
a little too good. Mitsuitei, the archaeologist, had once or twice
appeared to resent some of the young fellow's remarks, though not to
an extent where Lampert had felt the need for introducing his own
personality into the matter. Krendall, nearly twice Sulewayo's age,
seemed to be a check on the younger man anyway; he was a member of the
same profession, and Sulewayo would have been the first to admit his
respect for Krendall's work in the field. Under the circumstances,
Lampert felt that the group was well matched.

Whether it would be able to do the job it had undertaken was another
matter. The news reports had spoken glibly of the expedition which was
going to "solve the mysteries of Viridis once and for all." Lampert,
like any other scientist, knew perfectly well that the solution of the
present crop of mysteries about the planet would almost certainly be
achieved only at the cost of creating an even greater number of new
ones. Even the guide, who was admittedly no scientist, had expressed a
similar opinion, though his was based on a general pessimism bred of
familiarity with the planet. However, he had undertaken to get them to
the sort of country they wanted; and from then on the problem solving
was not his affair.

The scientists, whatever may have been their feeling about matters
of personal safety, were eager to start, which tended to cause rapid
progress in McLaughlin's animal recognition school. Another factor
tending toward the same result was that there was little in Emeraude
for such men to do, except learn. The town was still small. It had a
spaceport and airport, which furnished little entertainment, docks
which could amuse for a while but not indefinitely, and warehouses
which were completely uninteresting to geologists, paleontologists and
archaeologists. There was no museum. The numerous specimens of mineral,
animal, and vegetable matter collected on the planet invariably wound
up on outbound spacecraft. The zoo, which the town maintained for
purely practical reasons, was about the only thing that was left.

In consequence, not many days passed before all four scientists were
able to meet McLaughlin's requirements. Sulewayo was annoyed by the
guide's addition of a short postgraduate course in edible flora and
fauna, but admitted that the knowledge might well be useful. However,
he made no secret of his satisfaction when McLaughlin finally announced
that, as far as he was concerned, the journey could begin at any time.

All four rechecked their equipment--that of Lampert was by far the
bulkiest--and, everyone satisfied with the group's ability both to
live and to work in the steam bath that was the world of Viridis, they
watched the harbor on which Emeraude was located shrink and blend into
the rest of the shoreline behind them. Within a few minutes only the
restless surface of Green Bay was visible through the ever-present
haze....

       *       *       *       *       *

The jaws of the Felodon abruptly stopped moving and its forelegs
straightened, bringing the fanged head up and away from the kill it had
just made.

If a man had been there he would neither have seen nor heard the
disturbing factor, for a thunderstorm a few miles to the west was
emitting an almost continuous growl and the towering trees shut out
nearly all the sky. Nevertheless the beast appeared to sense something
out of the ordinary. It twisted its short but supple neck ceaselessly,
rocking its head from side to side to bring first one eye and tympanic
membrane to bear on the jungle roof, then the other. Sometimes it froze
motionless for a long moment, and a watcher would have sworn that its
minute brain was struggling with a thought. If this were the case, the
thought must have been both unusual and unpleasant, for under normal
circumstances nothing short of overwhelming force would have driven a
Felodon from its meal. Now, however, the hind legs slowly straightened
and the creature came erect. For another moment it stood motionless,
took a step or two away from the body, and stopped again.

Abruptly, as though in defiance of some impulse, it turned back,
lowered the murderously armed head and tore a huge mouthful of flesh
from the carcass. Then, like a child leaving the cookie jar as its
mother approaches, it leaped away into the underbrush, still swallowing.

Its speed was high and it did not have far to go. The jungle thinned in
a few hundred meters to the point where some sky became visible, and a
short distance further the riotous plant growth vanished completely to
give place to an open beach. Here the creature stopped and repeated its
search of the hemisphere overhead.

This time it found what it sought.

Along the line of the beach, perhaps a kilometer out to sea, the thing
came flying. It must have been utterly different from anything the
Felodon could ever have seen, but no sign of fear appeared in the
beast's demeanor. It stood on the beach, well away from the shelter of
the jungle and certainly in full view from above, its head following
the flying object and a fearful snarl--which might or might not have
been its normal expression of hunger--giving its face an almost
mammalian cast.

This thing was larger by far than any flying creature the Felodon
knew--incomparably larger than the Felodon itself. Its details were
hard to make out through the hazy air, and would have meant little to
the flesh-eater in any case. The most noticeable characteristic was the
steady, whistling hum that proceeded from it. There was a suggestion of
motion, too, which might have been wings or might not. Actually, the
thing was little more than a dark dot against the purplish-blue sky.
At the moment no sunlight was striking it directly, for it was in the
shadow of the thunderhead. Perhaps this prevented the animal below from
being bothered by another unusual feature it possessed, though even the
appearance of this last characteristic produced no sign of fear when
it finally came. This occurred shortly after the flying thing passed,
while it was still quite close. It moved out of the shadow of the great
cloud and, as the greenish sunlight struck it, the eyes of the watching
creature were dazzled by a gleam of metal.

This was certainly something it had never seen, for native metal on
Viridis is just about as common as it was on Earth before men began
to pry it out of its ores. Viridis has an oxygen-rich atmosphere and
plenty of moisture, and pure aluminum or chromium just doesn't occur in
that environment.

Strange or not, however, the gleam did not appear to affect the
Felodon's rudimentary sense of fear. For just an instant it paused as
the flying thing hummed on into the northeast; just once it looked back
toward the point in the jungle where it had left its kill--a point
from which eloquent sounds were now coming, betraying the presence of
carrion-eaters; just one step it took in that direction. Then it turned
away as abruptly as it had from the meal a few minutes before. With
the same purposeful air it had displayed on the way out of the jungle
it headed down the beach in the direction taken by the flying piece of
metal.

Though the animal's speed was high, the humming soon faded out ahead of
it.

However, this did not seem to cause any inconvenience; the Felodon
moved on, with a gait that might have been called a fast walk or a
slow run, never hesitating, never pausing. It remained silent. Smaller
creatures which might have given it a wide berth had they heard the
hunting call now sprang away almost from underfoot. It paid them no
heed, but continued on its way while the green sun settled into the
jungle behind and to its left. The fact that its recent kill was now
little more than a skeleton did not seem to bother it. Perhaps it had
forgotten.


                                  II

The humming was a little more noticeable in the helicopter cabin, but
not much. John McLaughlin, sprawled as comfortably as his two meters
of height would permit in its confines, had noticed the sound only at
first; and after remarking to himself that they seemed to be building
better ion turbines since he had left Earth, had permitted his thoughts
to wander in other directions. These did not concern Felodons; the
interest there was not, at the moment, mutual. The rather crowded cabin
offered material enough for consideration.

McLaughlin was not a scientist by training, but neither was he the
sort of guide that might have been found in Yukon or Amazon territory
a few centuries back. He did not despise people merely because they
were, by his standards, greenhorns. He knew that each of the other men
now sharing this cabin with him was an expert in his own field, even
though none of them, in spite of his training, would have been able
to survive for more than a day in the jungles of Viridis. After all,
why should they have learned such an art? There were other things worth
learning, and one could always hire McLaughlin if a need to visit the
jungles developed. Since this particular party had done just that, they
were evidently a fairly practical crew.

They were not talking very much, which from the guide's viewpoint was
an additional point in their favor. They already knew what they planned
to do, and saw no point in repeating what had already been said. Of
course, if they should fail to find the area they were seeking, there
would be talk--all of it aimed at McLaughlin; but he had no fear on
that score. There were few enough mountains on Viridis, and of those
few by far the greater number were volcanic cinder cones. When these
scientists had specified a region of tilted-block or folded mountains,
the guide had been more than dubious at first. It had taken him time to
recall that there was a small area meeting these specifications less
than fifteen hundred miles from the spaceport at Emeraude. He was not
himself a geologist, but pictures and diagrams had been used freely in
explaining to him just what was wanted, and he was quite certain that
the party would be satisfied with what he had to offer.

A slight rocking in the hitherto steady motion of the helicopter roused
him from this line of reverie. They were already several hours from
Emeraude, and McLaughlin realized that he should have been paying more
attention to the course. He straightened up in his seat and looked out.

To the left and ahead was a huge thunderhead, whose satellite air
currents had probably caused the variation on the helicopter's flight
path. More important, there was land in sight. McLaughlin knew that
the long flight across Green Bay was over. He waited, however, before
saying anything. He had given the pilot full instructions as to the
route before take-off, and he wanted to see whether those had been
clear enough.

Apparently they had. Without asking questions or even looking back at
the guide, Lampert swung the aircraft from its northerly heading onto
one which paralleled the shoreline, a turn of about forty-five degrees
to the right, and the helicopter resumed its steady flight.

McLaughlin did not relax. From now on the route was a little more
difficult to follow, and there were not too many more hours of
daylight. The shadowless night glow which made vision relatively easy
after sunset did not lend itself to aerial navigation over a very
poorly mapped world. He kept his eyes on the shoreline, watching for
the landmarks he had not seen for many months--and then not from above.
He did not see the Felodon which became so intensely interested in the
helicopter. If he had, he would have attached little importance to the
creature's presence, and he could not possibly have seen its actions in
sufficient detail to catch any peculiarities in them.

       *       *       *       *       *

No one else saw the beast, either. The change in course had roused most
of the party from whatever lines of thought they had been pursuing,
as it had McLaughlin, and most of them were looking out the windows;
but they were interested in what lay ahead, not below. Sometime soon
the relative monotony of jungle and swamp should be relieved by rising
ground, indicating the nearness of the mountains they sought; and the
helicopter's flight altitude of some two thousand feet was low enough
to permit any significant rise of terrain to be visible. Sulewayo, the
younger paleontologist, made a remark to that effect, which passed
without comment. Real conversation did not start for some minutes.

"As I understand it, we have one more course change before we see the
mountains. Isn't there a river we have to follow for a time, String?"
Lampert asked the question without looking back.

"That's right," McLaughlin replied. "It runs into Green Bay from almost
straight north, and about a hundred miles inland makes a turn to the
east. That's general direction. It winds a lot."

"It would, in country as nearly peneplaned as this," muttered Lampert
under his breath.

"The mountains you want start about sixty airline miles from the big
bend. If you trust your gyro compass enough, you can head for them
directly from the river mouth. If you have any doubt about being able
to hold a line, though, follow the river. I doubt that there are any
good landmarks otherwise. Of course, I've only seen the area from the
surface and close to the river, but I'd be very surprised if there was
anything around but the swamp-and-jungle mess we're over now."

"So would I. We'll stay in sight of the river, but edge as far east as
visibility lets us." The guide approved this plan with a nod, and the
conversation lapsed for several minutes. The silence was finally broken
once more by Sulewayo.

"I hope these hills we're looking for have something of interest. This
planet is the most monotonous I've seen yet. Where it isn't jungle it's
swamp; and the only difference between the two is that the jungle grows
higher trees." McLaughlin's face crinkled into something like a smile,
and he sat up once more.

"There's one other difference," he remarked.

"What's that?"

"In the jungle, dressed and equipped as you now are, you might live
as long as a day. In the swamp, five minutes would be an optimistic
estimate." Sulewayo looked down at the shorts and boots which
constituted his costume, and shrugged.

"I admit the point, but I don't expect to go out this way. What I
actually wear and carry, beside my professional equipment, is up to
you. Also, I was referring to appearances. Beta Lyrae Nine looked
almost as dull as this world from above, and I'll bet it was as
least as deadly when you reached the surface." McLaughlin had never
visited New Sheol, and admitted it, but it took more than that to stop
Sulewayo.

"Actually, I was hoping that these hills didn't turn out to be so
covered with soil that any fossils would be yards underground at the
best. Do you recall any places where the rock strata themselves were
exposed--steep cliffs, or deep stream gullies, perhaps?"

"Definitely yes. The big river cuts right across the range, or else
starts in it. It comes out from a canyon like that of the Colorado on
Earth, though a lot less spectacular. Actually I don't know anything
about the country more than a couple of miles up that canyon. I was
stopped on the river by rapids, and couldn't get my amphib out on
either side. For the most part there simply wasn't any shore, just
cliff."

"Quite a current, I suppose?" Lampert cut in.

"Actually, not very much. I went swimming in worse, on Earth."

       *       *       *       *       *

"That hardly ties in with steep cliffs and a river cutting through a
mountain range."

McLaughlin shrugged. "You're the geologist. Look it over for yourself.
Maybe you'll just have to add it to the list of things you don't
understand about Viridis."

"Fair enough." The pilot-commander-geophysicist nodded. "I did not mean
to imply that you were not reporting accurately; but the situation you
have described would be a trifle queer on more planets than Earth, I
assure you. Still, with luck your cliffs will show fossils. Maybe we'll
solve one problem in exchange for another. Life could be worse."

"Just hope we don't solve the first one by proving that certain
geophysicists have been talking through their hats," the hitherto
silent Krendall remarked.

"Eh?"

"What would you do if we found a chunk of, say, pegmatite with
radioactive inclusions that checked out at half a billion years instead
of the thirty-odd million you lads have been giving us as a time scale
for this mudball?"

"I should check very carefully under what circumstances and in what
location you found it. If necessary, I would admit that the problem had
disappeared. Half a billion years would account reasonably well for
the evolutionary status of this planet's life forms, though actually
it took Earth a good deal longer to reach a corresponding condition.
Frankly, however, I do not expect any such find. We spotted our borings
rather carefully, and should have taken pretty representative samples."

"I'm sure you did. If your results are right, it just means that the
problem belongs to Hans and me--and String here had better find us a
lot of fossils."

"You'll have to find your own bones," McLaughlin replied. "I'm taking
you to the sort of ground you want. A fossil would have to show its
teeth in my face before I'd recognize it--and then I'd probably shoot
before I realized it was dead."

"All right," Sulewayo chuckled. "You take care of the quick, and
Krendall and I will worry about the dead. Dr. Lampert can figure out
how old the fossils are if we find any, and Take can look for stone
axes."

"Or automobiles, or pieces of space-drive tubes, or other artifacts,"
Mitsuitei answered the implied dig. "I plan to sit back and loaf,
unless and until one of you lads turns up a skull that could have held
more than half an ounce of brain. I am going to be very unscientific. I
believe that there is nothing on this planet for an archeologist to do,
and I am not going to work myself into a lather to prove myself wrong."

"You've formed an opinion rather early in the game," Lampert remarked.
"After all, remarkably little of this world has been explored. Why
should there not be traces of occupation in unknown areas such as we
are about to visit?"

"Because, while most of the planet remains unexplored, a very large
number of places which should have furnished traces of habitation have
failed to do so. We've surveyed many spots which were, or are, ideal
for cities based on ocean commerce, or market centers for what could be
farm areas, or spaceports. After a while you get to a point where such
finds can be predicted with some certainty. As I said, I am far from
certain, and it would be most unreasonable to say I was; but in the
area we are seeking, I see no reason to expect anything of interest to
my profession."

       *       *       *       *       *

Lampert shrugged and brought his full attention back to the controls.
The sun was slowly sinking, bringing into bolder relief the
irregularities of the ground as their shadows lengthened. However,
these irregularities were still few, and the jungle roof was for the
most part evenly illuminated. As McLaughlin had expected, there was
nothing that could be used as a landmark. In its own way, the forest
was as featureless as the ocean. The pilot kept his gaze riveted ahead,
in expectation of the river which the guide had told them to expect;
and presently he saw it. Reflecting the color of the faintly purplish
sky, it stood out fairly well against the gray-green of the jungle,
once they were close enough to penetrate the ever-present haze.

With McLaughlin nodding silent approval, Lampert swung the helicopter
to the left and proceeded more nearly straight north, angling gradually
toward the river. Now the jungle took on a little more feature, though
still nothing that could be used for guidance. At fairly frequent
intervals a glint of water became visible through the trees directly
below them. Evidently numerous tributaries were feeding into the larger
stream; but none of these could be seen from any distance. For the most
part they were so narrow that the trees growing on each side met above
them.

"I should think that one could cover a great deal of that territory
in a boat," remarked Mitsuitei, after nearly half an hour in the new
direction.

"You'd need an amphib," replied the guide. "A boat is all right for the
main stream, but all that stuff coming in from the sides is so shallow
that you'd never make progress with anything else. I've tried most of
them in my own croc. Every time I've had to crawl rather than float
before I was a mile from the river."

"How is the ground? Swamp?"

"No, it's fairly solid for the most part. It doesn't show very well
yet even with the sun as low as it is, but the general ground level is
pushing up slowly all along here. We'll be in sight of your mountains
before too long."

This declaration brought all members of the group to the windows, all
five pairs of eyes covering the quadrant of vision below and ahead.
The meandering river was now on their left, but just visible through
the haze ahead of them was the eastward turn McLaughlin had predicted.
Lampert headed a little more to the right in an attempt to cut the
final corner, but the helicopter reached the winding purplish band
before their goal came in sight in spite of this effort. The flyer
hummed on.

The bars of sunlight admitted by the side ports had been nearly
horizontal when the turn to the east cut them off. They were only
slightly more so when McLaughlin gave a satisfied grunt, and nodded
forward. The others followed his gaze.

       *       *       *       *       *

Straight ahead, little could be seen because of the "bright spot"
familiar to every flyer--the shadowless area directly opposite the sun,
centered on the aircraft's own shadow. To either side, however, the
promised hills rose out of the jungle to heights exceeding the present
flight altitude of the helicopter. Presumably the canyon from which
the river was supposed to emerge lay in their path. So, at any rate,
Lampert remarked; and McLaughlin confirmed him.

"I'd cruise pretty slowly from here on," the guide added. "There are a
number of hills on this side of the range. Even if you're not worried
about running into one of them, you may want to examine them for
exposed rocks."

"Mightn't it be better to find a spot to park before the sun goes
down?" countered the pilot.

"It might. What I said still holds, though. You haven't much chance
finding one inside the canyon without quite a long search, and it will
be best to stay this side of the range until sunrise. Remember my
trouble in finding a beach for the amphib while I was inside."

"All right. Can we land in jungle, though?"

"Not unless you want to fold the blades in flight and drop the last
twenty to fifty feet. Hunt for a fairly high hill. They're usually
somewhat bare on top, and you'll at least have room for the rotors to
swing. If you don't like that, or can't find a suitable hilltop, land
on the river and tie up to the shore--but again, don't try that in the
canyon. You're unlikely to find anything to tie up to."

"This machine has good lights, I suppose you realize--but then, you
know the planet. As far as I'm concerned, what you say goes. Are the
chances of a hill equally good on either side of the river?"

"Maybe a little better to the north. The ground looked higher that way
when I came out of the canyon." Lampert obediently eased the flyer's
course a trifle to the left, and everyone aboard watched the ground as
it began to rise toward them.

At first the "hills" were merely low mounds, as jungle-covered as the
level ground; but very quickly these gave way to higher, steeper rises
on whose tops the larger trees grew very sparsely. One of these was
quickly selected after a brief, questioning glance from Lampert to the
guide, and the helicopter began to descend.

"We'd better take what we have now." McLaughlin amplified the nod with
which he had answered the pilot. "This belt of hills is pretty narrow,
and we'd be into the main range in another minute or two."

"Do you know whether the other side is as abrupt, or whether--"
Lampert's question was cut short by an exclamation from Mitsuitei.

"Rob! Hold it a moment!"

Lampert was a good pilot; the increase in rotor-blade pitch under his
deft fingers brought the helicopter's descent to as nearly an instant
halt as was possible to anything airborne. Not until he had also
checked horizontal drift did he look in the direction the archaeologist
was indicating. By then, everyone else had seen what had attracted
Mitsuitei's attention.

Between the hill on which Lampert had intended to land and the river
were several lower eminences. These were now almost directly south
of the helicopter, and every detail upon them was shown in exaggerated
relief by shadows stretching to the east. It was one of these hills
which Mitsuitei was examining with the utmost care.

It was covered with jungle, like the rest; but a curious regularity
was visible. The trees appeared, at this distance, to be of the usual
species; but some of them towered over their fellows by a good thirty
or forty feet.

This in itself was not odd. The whole jungle was studded with such
projections. However, on this hill the taller trees seemed to have
been planted in orderly rows. Five solid lines of them were visible,
extending roughly north and south so that their long shadows made them
stand out sharply. They were separated from each other by perhaps a
quarter of a mile. Running at right angles to them were other, less
outstanding rows of vegetation. Lampert was not quite sure that these
were not the product of his own imagination, since the trees which
formed them rose little if any above the general level. The whole
hilltop, however, suggested something to every man who saw it. The
archaeologist was the first to give voice to the impression.

"That was a city!"

       *       *       *       *       *

No one answered. Some of the scientists must have thought that he was
jumping from one opinion to its direct opposite on the strength of some
rather feeble evidence; but the thought went unvoiced. They simply
looked--except for Sulewayo, who moved to turn a camera on the scene.

"Rob! Can we land there? Now?" Lampert had anticipated this question,
but could have answered it without hesitation in any case.

"Sure--if you don't mind using String's method of folding the blades
and falling in." The archaeologist turned to the guide.

"Will it be hard to get there on foot from this hill we're heading
for?" McLaughlin shrugged.

"From two hours to a day, depending on undergrowth."

"We have torches. We can burn our way if the vegetation is dense."

"Half a day, then. You'll still have to let the steam clear pretty
often. There's little wind below the trees, and the air is saturated."

"Well, that place will be worth more than a day of anyone's time. Maybe
tomorrow we can--"

"Hold up a moment, Take!" Lampert cut in, before Mitsuitei could
develop his plan further. "If you take String out to that hill
before take-off tomorrow, what do the rest of us do for the day--or
week--before you get back? What we'd better do is note this place,
go on to the canyon, set up camp, get the fossil hunting going, and
_after_ our routine is set up and we know the more common dangers of
the neighborhood, perhaps we can spare McLaughlin for a day or two so
that you can look over your city--if that's what it is."

Lampert's last few words banished the hurt expression from the little
man's face.

"What do you mean--_if_? What else could make a pattern like that? It
must have been streets."

"Or a joint system in the rock below, trapping enough water--or
draining enough off--to permit superior growth along the joint lines.
Or a system of tilted strata doing the same thing--"

"If it's the latter, it's just the sort of thing you want, too. It
should bring fossils near the surface."

The pilot nodded slowly. "You do make it sound more attractive. Still,
I think we'd better follow the original plan, except that I may come
with you myself when we do get around to looking that hill over."
He turned back to the controls and resumed their descent. Mitsuitei
subsided once more to his seat. The archaeologist realized the wisdom
of Lampert's decision, but did not particularly enjoy the enforced
wait. His face showed the fact, until Sulewayo opened the camera he
had been using and passed him the sheaf of prints on which the "city"
appeared. As the young paleontologist had expected, these so occupied
the little man's attention that he did not even notice the landing.

       *       *       *       *       *

The helicopter settled to the hilltop which Lampert had chosen, in the
center of a quadrangle of trees growing just far enough apart to give
clearance to the rotors.

The sun was nearly gone. It had vanished in the haze as they dropped
below flight altitude. McLaughlin knew that in all too short a time
it would be as dark as Viridis ever became. The nights could be
dangerous. There was quite enough light to deceive a man into thinking
he could see clearly, and an inexperienced wanderer might not realize
until too late that details were not really distinct and that there was
no clue to direction in the shadowless glow. McLaughlin himself could
use the moons, but he doubted that any other member of the party could
do so. They--or their motions--took knowing.

He was pleased to note that there was no general rush to the door as
the great blades whistled gently to a stop. The scientists turned to
him, but remained where they were. No words were spoken, but Lampert's
relinquishment of command was evident. McLaughlin unfolded his length
from the seat.

"There are two choices," he said. "We can sleep in the 'copter, or
outside. The first will be a trifle cramped, but the second will
require either a double circle of charged wire or two armed guards on
constant watch. With no offense meant, I doubt that anyone but myself
in this group could qualify as a night guard."

"Why a double circle of wire?" asked Lampert.

"The wire will stop only an animal in control of its motion when it
makes contact. If a Felodon were to spring from a little distance, it
might not like the wire--but it could hardly stop until it reached the
ground, and there should then be a similar barrier ahead of it."

"We could use a lethal voltage."

"Even if you want to take the risk--what is lethal to a Felodon will
be equally so to a man--you'll have the insulation problem. There's
always a darned good chance of rain before morning, and--"

"We might as well stay inside, then. We have the electric equipment,
but it will take quite a while to set it up; and it hardly seems worth
the trouble for a one-night stand. As you say, it will be a little
crowded here. But we've all slept under worse conditions. Would anyone
rather set up the fence?"

There was no answer to this question. At Lampert's direction a meal
was served and eaten. Then the scientists settled down for the night,
some to sleep at once, others to review plans or recheck equipment.
Mitsuitei occupied himself with making careful measurements of the
photographs he had been given; he was the last asleep....

Scores of miles to the southwest, the Felodon reached the river. It
was no longer on the coast; some time since it had swerved inland. A
casual compass check would have revealed that it was still heading
straight for the now grounded helicopter. Even McLaughlin could not
have told what led the creature on, familiar as he was with the animals
of Viridis; but no one who had watched the thing since the flying
machine had passed could have doubted its goal. Actually, it was now on
the same bank of the river as the helicopter; but whatever guided it
pointed across the great stream.

Without hesitating, the amphibid plunged into the water.


                                  III

The men were awake well before sunrise. The human body takes a long,
long time to accustom its physiological cycle to a change in something
as fundamental as the length of day. But they did not attempt to resume
flight until the green star was once more in the sky. Mitsuitei put
forth a tentative suggestion that the interval be spent in a visit to
the "city" site he had seen the night before, but McLaughlin vetoed it.

"Going on foot through the jungle at night is a fool's game, though I
admit people sometimes get away with it. I could get you there, but
even if we turned around and came back immediately there'd be a lot of
time wasted. Dr. Lampert went over all that last night. Look, that hill
of yours is right by the river. After we're set up in the main camp, it
will be relatively easy to drop down to it. We have collapsible boats.
Unless we camp above the rapids, you won't even have to fly. Even if
we're farther upstream and do have to use the 'copter, the trip will
take only a few minutes."

Mitsuitei had agreed, though with evident reluctance. No one else had
any desire to go out; there was not enough rock exposed on the hilltop
to excite the paleontologists, the hill itself presented nothing
unusual to Lampert's geophysical eye, and McLaughlin was in no hurry
to get to work. They waited, therefore, until the "Claw"--Lampert had
recalled Beta Librae's Arabic name--had risen and the skyglow been
replaced by its emerald brilliance; then the journey was resumed.

It took, as McLaughlin had said the night before, only a few minutes.
The hill where they had slept was less than five miles from the face
of the mountain range. Only the haze of the night before had prevented
their seeing it. The river emerged from a canyon some fifteen hundred
feet in depth, a couple of miles to the south of their eastward course
line.

Lampert, in hopes that the usual haze might not be too evident at
this hour, climbed above the level of the cliff top to get an idea of
the mountain range as a whole; but he was disappointed. For nearly an
hour he cruised over the area, now several thousand feet above the
western cliffs and then well below them. It slowly became evident that
the range represented a single block, which had been tilted upward
on the west side. The opposite slopes were very gentle, merging so
gradually into the general peneplain level of the continent that it was
impossible to say decisively just where the range ended. The river did
originate somewhere beyond the range, cutting entirely through it, and
as the guide had said, its current was not particularly swift. Lampert
had much explaining to do. After all, water should have drained toward
the low side of the block.

"It seems evident," he summed up his ideas as they hovered once
more over the western cliffs, "that the river was here before this
particular bit of block tilting occurred. This planet does have some
diastrophic forces left in its crust, in spite of its generally smooth
nature. Apparently this just represents the end of a long period of
rest, such as the earth has had several times. As a matter of fact, I
have no business calling it the end of such a period; it might be fifty
million years before the world will be generally mountainous again."

"Why do you say _again_, Rob?" asked Krendall. "According to findings
of your own colleagues, this planet has hardly been solid for forty
million years. Could it be this flat now if it had ever been markedly
mountainous in that time?"

"Good point. I don't know, but would be inclined to doubt it. Well,
we'll cancel the 'again' if it will make you happy. In any case the
block forming this range came up slowly enough so that even this river,
with its relatively low cutting power, was able to keep pace with it
and not be deflected. Probably--" he glanced at Mitsuitei--"the rock of
which it is made will turn out to be quite strongly jointed. It looks
rather that way from above--the river course, I mean. A lot of right
angle, or what were once right angle, bends."

"We'd better go down and look for a camp along the river somewhere,"
put in Mitsuitei. "Let's start at the cliff end. Then we may wind up
reasonably close to that hill--and I still want to look it over, joints
or no joints."

"Fair enough." Lampert eased the helicopter once more downward until
they were only a few hundred feet above the jungle, moved along
the cliff face until they reached the canyon, and, very cautiously,
entered. His caution proved unnecessary. The air currents in no way
resembled the treacherous hodge-podge he had expected, at least not
over the center of the river. A steady wind was blowing into the canyon
mouth, but did not seem to be eddying very much even at the numerous
bends.

       *       *       *       *       *

To the archeologist's annoyance, two sets of rapids were passed before
a place was reached where the bank was wide enough for a camp site.
At this point a fairly large side canyon entered the main one from
the north. Where its central stream joined the main river a gravelly
area several acres in extent offered itself for the purposes of the
scientists. Lampert brought the helicopter down on this surface. The
surroundings looked promising; the cliffs facing both canyons looked
reasonably accessible on foot for some distance, at least along their
bases. Climbing appeared to be impracticable for the most part, as the
rock walls rose sheer except for the occasional joints which Lampert
had predicted; but the material was certainly sedimentary, and everyone
but the guide tumbled out of the flyer with a glow in his eyes which
promised a speedy scattering of the party.

With some difficulty, McLaughlin got them together. A site, some twenty
yards square, was selected against one of the cliffs and fenced off.
The big, prefabricated sheet-metal "tent" was erected and its tiny
conditioning unit installed; sleeping and cooking gear were placed
inside. That completed, geologist's hammers appeared as though by
magic; and McLaughlin realized that he had better do some explaining
before he lost a scientist or two. Once more he called them together.

"All right, gentlemen. I admit the necessary camp work has been done,
and there should be nothing to keep you from your projects. Still,
there are some things you had better understand.

"Having canyon walls on all sides does not make this place safe. Every
carnivore and poison lizard on this planet could get to us by way
of the river--even the ones which look like land animals. Every one
of them could swim under water from a point out of sight in either
direction to where you are standing; and if you think he would have
to come up at least once to judge your position, guess again. I don't
know how they do it, and neither does anyone else; but a Felodon could
submerge around the bend up there, come up behind the helicopter out
of sight of any one of us and be waiting when we marched around the
machine. Therefore, go armed at all times. I know you want to cover
a lot of ground, and can't stick in one party; but I insist that you
do not go anywhere alone. Take at least one companion. Preferably one
who is not a member of your own field. If you two paleontologists are
together, for example, it seems more than likely that you'll be found
with your heads in the same hole in the rock. When one of you has to
dig, make sure the other has his neck on a swivel. I know this will
slow your work, but not as much as if the work had to wait for a new
investigating team from Emeraude--or from Earth.

"You've seen most of the dangerous animals in the zoo at Emeraude, so I
won't waste time describing them. Just remember that you won't always
hear them coming. You'll have to use your eyes.

"All right, Dr. Lampert. You're the boss, as far as the scientific work
goes. Who does what, and where?"

       *       *       *       *       *

The geophysicist gave no sign of having detected the humor in the
guide's remark, but began speaking at once.

"I should say that the main canyon upstream and the side one in the
same direction should be covered first. We've already used up a good
deal of today, and would waste more breaking out the boats. Ndomi and
I will go up the main stream; Hans and Take can take the other. Don't
hurry. If anything looks good, take the time to investigate it on the
spot. Of course, if it is obviously a major job, just mark it and go
on. There's no sense in one man's trying to exhume a six-foot lizard
skull.

"Since this region must have been sea when the limestone was deposited,
there's not much chance of land animals. However, we want as complete a
chronological series as possible, so do the best you can on this level.
We'll try for higher formations later. There should be plenty farther
upriver, if this block is tilted the way it seems to be.

"String, perhaps you'd better go with Take and Hans. Set out when
you're ready. Be back in--" he glanced automatically at the narrow
strip of purplish-blue sky, then at his watch--"four hours; then we'll
compare notes. After that we can either concentrate on one place or the
other, or break out the boats and cross the streams, as indicated."

Twenty minutes later the parties were out of sight of each other and
the helicopter. Lampert had spent the first few minutes of the walk
wondering whether he had been too obvious in arranging for both the
guide and Krendall to accompany the little archaeologist; but he
quickly convinced himself that McLaughlin's speech had covered the
arrangements pretty well.

In any case, he would probably have been distracted soon enough. The
cliffs were interesting. Limestone, evidently, as expected--but rather
dense, at that; maybe some barium replacing the calcium? or was the
gravity different enough to destroy his judgement for such a small
fragment? Probably not. He was actually using inertia more than weight
in making his estimate. Anyway, the stuff was certainly a carbonate. It
frothed satisfyingly under a drop of acid from Lampert's kit.

And there were fossils. Sulewayo's form was bent over a spot on the
cliff face, examining minutely; but Lampert could see others from where
he stood. None seemed remarkable. Most were rather evidently shellfish.
He carefully refrained from giving them names according to the genera
they resembled in Earth's rocks; Sulewayo and his colleagues frowned on
the practice, which could be most misleading. He could not, however,
resist the temptation to think of them as scallops.

"What do you have there, Ndomi?" He knew the other would not have spent
so long on any shellfish.

"Not sure, precisely. Maybe vertebrate, maybe not. What could be armor
and what could be ribs all mixed up. I think I'll mark it for future
reference."

"I suppose it'll be another Devonian whatsit, like everything else on
this planet, when you do decide."

"Pennsylvanian would better describe the world as a whole. Barring
that, you may be right. Rob, if you'd give me a hand here we could get
some basic work done."

"Eh?"

"You say this is a tilted block. In lowest formations right now. I'd
like to get photos and if possible specimens of as many different
varieties of shellfish as possible, at each level. Then it may be
possible to set up some sort of temporal sequence--and use the things
as index fossils if animals do evolve on this be-nighted mudball.
If you could get me some radioactive dates at two or three nicely
scattered levels, it would also help."

"Thanks," returned Lampert drily. "I could use material like that
myself. I can tell you what you probably already know--you're not
likely to get anything of the sort from limestone."

"Well--intrusions are always possible."

"You watch for 'em, then." The pair went to work.

       *       *       *       *       *

Two hours out, a little more than one back. There was no one at the
helicopter when they reached it, but the other group came in only a
few minutes over the four-hour limit which Lampert had imposed. A
comparison of notes over the meal which had been quickly prepared
indicated that the second group had gone farther in point of miles
covered, but had accomplished less work. Krendall had had the same
idea as Sulewayo. But he had not attempted to carry it out since his
canyon did not cut across the range, and would presumably not furnish a
continuous change in formations.

Lampert and Sulewayo, as it happened, had not found any evidence of
change themselves. The last fossils they had found were at least
superficially identical with the first. There was the usual evidence
of bedding, and it had been quite evident geometrically that the walk
had taken them to originally higher, and presumably later, levels; but
in what must have been eight hundred feet or more of original deposit,
there seemed to have been no significant change in the fossil life.
What eight hundred feet would mean in point of time, of course, no one
had the least idea. There was not even a good guess as to how fast
carbonates might be expected to precipitate in a Viridian ocean. Anyone
could compute the carbonate ion equilibrium between atmosphere and sea,
but no one knew anything to speak of about carbonate-precipitating
organisms of the planet.

Mitsuitei changed the subject slightly at this point.

"We found several of the joints you predicted," he said to Lampert.

"Oh? Very wide? We didn't spot anything that was obviously a joint. But
there were several small side canyons--all narrow enough for us to wade
or jump their central streams--which might have started life that way."

"Ours were quite narrow, and bore traces of volcanic ash at the
bottoms."

"Eh?"

"That's right, Rob. Here's a bit of it I brought back. I thought you
might want a little corroboration on that one." Krendall handed over a
bit of crumbly tuff as he spoke. Lampert examined it with pursed lips.

"Maybe we'd better get back into the air, and search the neighborhood
for volcanoes," he said at last. "I can't bring myself to believe in
two full mountain-building cycles on this planet--and if I could, I'd
have a hard time swallowing the idea of these limestone layers coming
up, going down, and coming up again unaltered. How deep were these
volcanic deposits?"

"Variable. Shallowest in the wider joints; in the very narrow ones, up
out of sight."

"Suggesting that they've been washing out for some time since the
original settling. Anything organic in them?"

"Nothing turned up yet."

"Do they extend below the present river level, or what?"

"They're at least down to it. We couldn't do any major excavating."

"If they run much below," muttered Lampert, "I'll join the roster of
geophysicists who have been driven off the rails by this woozy world.
Well, let's assume as a working hypothesis that the volcanic activity
is relatively recent. That will at least have the advantage of keeping
me sane, until something comes up to disprove it." He finished his meal
in silence, while McLaughlin gave a reproving lecture on the matter of
wading.

       *       *       *       *       *

There was still a little daylight to go when all the men had eaten;
and Lampert, Sulewayo and the archaeologist took the helicopter up the
main canyon to check on the possibility of walking to any really new
deposits.

They were sure, from changes of color already seen at various levels
up the cliff face, that these existed. But it appeared that the lowest
of them did not reach river level for more than a dozen miles. The
distance was less mapwise, but the canyon, winding back and forth
around what the geophysicist still felt must be joint-bounded blocks,
went a good two miles in other directions for each one that it led
eastward. Realizing this, the explorers lifted the helicopter and began
checking as close to the cliffs as Lampert dared at higher levels.
In this way they worked back toward the camp site. Once again it was
Mitsuitei who first spotted something of major interest.

"Found another city, Take?" asked Sulewayo at the other's call.

"Not exactly. It's--well, I guess it's really a system of those joints
you keep talking about. Still, it looks awfully regular." He sounded a
little wistful.

"It does." The paleontologist nodded slowly. "As you say, it's probably
a joint system. Also, it's probably full of volcanic ash, if my eyes
don't deceive me. Rob, what's the chance of a landing on one of the
shelves? There are at least three formations accessible on foot from
that point; and I could get some more tuff samples to make or break
your peace of mind, while I was doing my own work."

Lampert examined the area carefully. Like Earth's Grand Canyon, this
one receded from time to time in shelves where softer layers of rock
had worn further back, or the orogenic processes had paused to give the
river a longer bite at that level. The cracks Mitsuitei had seen formed
a neat crisscross pattern on the top of one of the shelves. Some of
them betrayed their nature by emerging from its vertical face. It was
admittedly an unusually small-scale joint pattern, at least for this
mountain system, and might well contain readable evidence of the forces
which had shaped the area.

However, they had only one helicopter. Lampert slowly shook his head in
negation.

"I'm afraid not, Ndomi. Your shelves may be big enough, but they're not
level enough. I'd have to make a swinging landing, and I'm not that
good a pilot."

"Well, how about letting me down on the ladder? We have a hundred feet
of that, so you could be up above the next shelf while I went down.
You'd have plenty of blade clearance. That next level goes back a
couple of hundred feet."

"That might be all right." Lampert spoke hesitantly. "You certainly
have the right to risk your own neck on the climb if you want to. We
won't try it tonight, though. I'd like to check with String on the
advisability of your being there alone. The place looks pretty hard to
reach for anything that doesn't fly, and I don't know of any really
dangerous flying things on this world; but we'd still better check."

"All right with me. I'd just as soon have a full day, anyway."

"If Ndomi will be spending a day alone up here, how about having String
take me to the other place, and settle that point once and for all?"
asked Mitsuitei as the helicopter eased downward toward the camp. "That
would still leave Hans and you to form another team for whatever else
you want to do."

"That should be all right. It'll depend, though, on whether String
thinks it's safe for a man to work alone on that shelf."

The proposition was put to McLaughlin as soon as the machine was
landed. To Lampert's surprise, the guide gave a qualified approval.

"Remember," he concluded, "I don't know what lives on the cliffs. It's
country I've never covered. All I'm saying is that no Viridian animal
I know of could get there, except flying ones; and they're nothing
to worry about, especially in the day-time. I'd like to go with you
to look over the place when you take him up tomorrow, and strongly
recommend that he carry a communicator as well as a weapon; but unless
I see something you haven't mentioned when I do go, I would say it was
all right...."

Once more the Felodon reached the river, but this time it did not
cross. It was no longer heading straight for the helicopter. Hills
had not altered its course, but the cliffs had. They formed a wall on
its right which was too nearly vertical for its agility and strength.
Even this barrier, however, had caused no visible hesitation or doubt.
It had swerved, followed the base of the wall to the point where the
river emerged and plunged in as promptly as it had done before. Few
amphibians have ever lost the art of swimming when their larval gills
vanished; the feeble current meant nothing to the Felodon.

It turned upstream and went on its way.


                                  IV

Ndomi Sulewayo had pursued his occupation on terraces of Earth's
Grand Canyon, on cliffsides of Fomalhaut Four's highest range and in
badlands on the dimly lighted Antares Twelve. The physical hazards of
his present position troubled him little. McLaughlin had agreed that
the ledge where the paleontologist had been left was inaccessible to
the larger carnivores, and had merely issued a final warning about
poisonous "lizards." The primary danger, as nearly as Sulewayo could
see, was that something might happen to the helicopter. He certainly
could not rejoin the others on foot. He was facing a sheer wall some
sixty feet high. A score of yards behind him the terrace ended in
another straight drop of several hundred feet. A quarter of a mile on
either side, the flat surface ended; to the west, by narrowing until
the two walls became one; at the other end, it was cut off as far as he
was concerned by a joint penetrating apparently the full depth of the
canyon.

There were several other cracks in the wall facing him. Like those in
the tributary canyon explored by Krendall and Mitsuitei, these were
packed with volcanic detritus. This was hard to reconcile with the
suggestion that erosion had been long at work. In such a case, the
higher portions should have washed away long before the material found
at the canyon bottom.

Examination at close range suggested a possible explanation. The tuff
at this point was fairly well cemented. It seemed reasonable to suppose
that the joints had been present before the mountains had started to
rise; that a volcanic mud flow had filled them with detritus; that the
new material had then been cemented by dissolved material coming from
above. This would make the top levels of the tuff more resistant than
those lower down, where the cementing minerals had not reached, and
account for what had been seen so far.

The hypothesis also implied a plentiful supply of fossils. Volcanic
mud flowing into a crack in the ground should carry plenty with it.
Sulewayo set to work with a hammer, and was presently soaking with
perspiration.

He was tempted to remove some of his clothing; but this had been
treated chemically to repel Viridian insects and caution prevailed.
McLaughlin had not mentioned any dangerous biters or stingers, and
in all probability his blood would not be to the taste of any such
creatures on this world--but if the mosquito or tick did not learn that
fact until after it had tried, Sulewayo would hardly profit by it. In
any case the temptation to strip passed quickly. In only a few minutes,
his attention was fully occupied by his work; for the expected fossils
proved to be present in very satisfactory numbers.

Most seemed rather fragmentary. Apparently the original creatures had
been tumbled about rather badly before the medium hardened. However,
the remains were definitely bones, as he had expected and hoped. For
some time Sulewayo was occupied alternately digging out more fragments
and trying to fit the more hopeful-looking specimens together, although
he had no success at the latter job. Then evidence of a more complete
set of remains appeared, and he instantly slowed down to the incredibly
meticulous procedure which marks a paleontologist anywhere in the
universe.

At this time he had cut perhaps a foot into the tuff for the full
three-foot width of the crack and from terrace level up to about his
own height. In spite of its apparently firm texture, the rock was
extremely soft; and the old question about erosion was reappearing. Big
pockets of extremely crumbly material had been responsible for most of
his speed. Now, however, with the usual perversity of the inanimate,
a firmer substance was encountered, apparently encasing the bones he
suspected of existing a little farther on. This combined with his
increased care to bring almost to a halt the removal of rock from the
cleft.

       *       *       *       *       *

The bones were there. Perhaps they had been betrayed by a discoloration
of the rock too faint for him to have noticed consciously; perhaps
something more subtle is involved in the makeup of a successful field
worker in paleontology, but as flake after flake of the matrix fell
away under his attack a shape gradually took form.

At first a single bone which might have been an unusually short
digit or an unusually long carpal--or, of course, something totally
unrelated to either--was outlined. Then another, close enough to
suggest that their lifetime relationship might have been maintained.
And another--Sulewayo failed to hear the approach of the helicopter
until its rotor wash from a hundred feet above lifted the dust about
his ankles.

Knowing that Lampert would be having trouble holding that close to the
cliffside, the paleontologist reluctantly hooked his equipment to his
belt and started up the ladder. Five minutes later they were back in
the camp, with Krendall listening eagerly to Sulewayo's description of
his find.

"It's certainly a vertebrate, Hans. That stuff can't possibly be shell
or wood. It's almost certainly a land dweller--"

"Likely enough in that sort of rock, anyway."

"--because I got enough uncovered to be nearly certain that it's a
foot. Certainly a limb that would not be needed by a swimmer."

"Like an ichthyosaur?" queried Lampert innocently. Sulewayo grinned.

"Quite possibly. More likely one of our ubiquitous amphibids, though.
Certainly something worth getting out, since the general idea is to get
an evolutionary sequence of some sort."

"I suppose that means you'll want me to date the eruption which filled
all these cracks with detritus, then."

"Sure. But there's no hurry. Tomorrow will do." Lampert found he had no
answer to this, and Mitsuitei managed to edge into the discussion. He
had spent the day with McLaughlin, as he had hoped; and mere failure to
find paving stones had not damped his ardor.

"I suppose you and Hans will both want to go up the cliff tomorrow," he
remarked. "In that case, Rob might as well stay with String and me. It
will speed up the digging back at my hill."

"Are you still scraping dirt off that thing?" asked Sulewayo in mock
surprise. "Didn't one day indicate that it was a joint pattern like the
rest?"

"Not yet. We haven't gotten down to rock over any place where your
cracks should be. The root tangle of the taller trees slows the
digging. I admit the rock is limestone like the cliff, but there's
still no evidence why those trees grow so regularly."

"That's just what we've been saying all along; but you keep looking for
the remains of a city."

"I gathered, Ndomi, from your recent conversation that you were digging
for a land animal on the basis of three bones. Either you are working
on hunch, which destroys your right to criticize, or you are reasoning
from knowledge not available to the rest of us. In the latter case,
you should be at least open-minded enough to credit me with equivalent
knowledge in my own field."

It was Sulewayo's turn to have nothing to say; he had honestly supposed
that the archaeologist had been taking the "city" hypothesis no more
seriously than the rest. He apologized at once, and peace was restored.
Lampert sealed it by agreeing to Mitsuitei's suggestion.

The rest of the evening was spent in detail planning by the two
groups. At sunset, all turned in to sleep behind the protection of
the electrified fence. Even the guide regarded this as an adequate
safeguard.

       *       *       *       *       *

Apparently his opinion was shared by at least one other. The Felodon
had spent most of the day under water, part of the time in the canyon
fairly close to Lampert and Krendall and later down the stream by the
site where the guide and archaeologist had been working. At neither
place had it emerged, or shown the slightest sign of wanting to attack.
McLaughlin's reference to the strange instinct of the creatures seemed
justified. It certainly could not see the men, but just as certainly
was aware of their presence.

What it was about the alien visitors which exercised such an influence
on the minute brain of the carnivore, no one could have said--then. Any
watcher who had supposed, from its earlier actions, that it was moved
by a desire for new and different taste sensations would have had to
discard the notion now.

With the men safely settled down behind their fence, the beast suddenly
turned back downstream. It had returned to the camp site at the end of
the working day. In an hour it was in the jungle below the canyon; in
another it had killed, and was feeding as it had the moment before the
hum of the helicopter had first attracted its attention. This time it
finished the meal in peace; and once finished, did not show immediate
signs of its former obsession.

Instead it sought a lair and relaxed, blending so perfectly into the
undergrowth and remaining so silent that within a few minutes small
animals were passing only feet away from the concealed killer.

Robin Lampert was only a fair statistician, but if he had been
acquainted with the moves of that Felodon during the last few days,
even he would have been willing to take oath that more than chance was
involved. He would probably have wanted to dissect the animal in search
of whatever mechanism was controlling it.

But Robin Lampert knew nothing of the creature. Neither did Takehiko
Mitsuitei; and that was rather unfortunate, for the lair it had
selected was on the same hill as the archaeologist's digging site, and
a scant quarter mile away from the pit Mitsuitei had left.

       *       *       *       *       *

The rising of the green sun was not visible the next morning. The
ever-present mist had thickened into a solid layer of cloud, and
hissing rain cut the visibility to a few hundred yards. The helicopter
felt its way down to the hill with radar, landed on the river, taxied
on its floats to the bank and was moored. Lampert, McLaughlin and
Mitsuitei emerged, the scientists laden with apparatus, and started up
the hill toward the site. The guide carried only his weapons.

The equipment was not of the sort Mitsuitei was accustomed to using.
It actually belonged to Lampert. Normally it would not be used in an
archaeological dig, any more than it would have been had they been
fossil hunting; for neither activity takes kindly to any sort of
automatic digging machinery. Lampert had suggested its use, however,
in order to get a rapid idea of the nature of the soil cover, bed rock
and joint structure of the hill. If evidence warranted, it would be
abandoned for the slower methods of digging. If not, a few hours would
permit them to learn as much about the area as many days of work with
slower equipment.

The hole Mitsuitei had already dug was part way up the hill, in a space
cleared of underbrush by a flamethrower. Several other such clearings
were in the neighborhood. As the archaeologist had said, he had made
more than one attempt at digging which had been frustrated by roots.

Somewhat to Lampert's surprise, it was possible to tell even from
ground level the orientation of the taller trees which had been so
prominent from the air. Even the smaller plants showed signs of some
underground influence. Between the tallest trees, tracing out the
straight lines the men had seen from above, the underbrush formed an
almost impenetrable wall. Elsewhere foot travel was easy, though the
surface was by no means barren. Lampert understood how there might
indeed have been difficulty in digging on one of the fertile lines, and
admitted as much.

"That's the trouble," responded Mitsuitei. "I'd like to get down
right at such a point, to see what's underneath. It seems to me that
paving might be responsible, if they'd used the right materials. Lots
of civilizations have used organic substances which decay to good
fertilizer. Then there might be the remains of a sewage system, which
would account for richer soil--"

"After the time which must have passed since the place was buried?"

"It has happened. In such a case, of course, trace elements rather than
nitrates or phosphates are responsible. That's what I suspect here."

"But wouldn't it be better to dig where you actually have--in the
middle of a block, if that's what it is? Then you'd be fairly certain
to hit a building, which should be richer ground than a street."

"Only if you actually strike artifacts. The building itself might be
much less well preserved than a paved street. However, you are the one
who's handling that mechanical mole. Dig where you want, and see what
you can learn about this hilltop. Just get me at least a couple of
cores from my 'streets' before you're done, please."

Lampert nodded and proceeded to assemble his equipment. The "mole" was
a cylinder about five centimeters in diameter and three times as long.
A cutter-lined mouth occupied one end, while the other was attached
to a snaky appendage which was wound on a fair sized drum. A set of
control knobs and indicators were mounted near the center of the drum.

The geophysicist set the cylinder on the ground mouth downward, pushing
it into the soft earth far enough to assure its remaining upright. Then
he turned to his controls and after a moment, with very little noise,
the cylinder began to sink into the ground. In a few seconds it was out
of sight, trailing its snaky neck after it.

The men watched it in silence. Perhaps thirty seconds after it
disappeared, there was a minor convulsion in the neck, a momentarily
rising hum from the machinery, and a plug of dirt about two centimeters
in diameter and five long was ejected from a port in the center of the
drum. This was seized by Lampert and examined briefly, then tossed
aside. "The soil is pretty deep," he remarked.

"How far down did that come from?" asked Mitsuitei.

"One meter. That's the sampling interval I've set in it, for now. If
it meets anything much harder or easier to penetrate, it will warn me
and I'll grab them more frequently." Conversation lapsed while two
more samples arrived and were inspected. Then a light flickered on the
panel, and Lampert reset one of his knobs; and almost immediately a
core of light gray limestone was produced.

"Apparently the same stuff as the cliffs," said Lampert after examining
the specimen. "Do you want to go any deeper, or drill a few more holes
to get an idea of the contour?"

"How fast will that thing go through limestone?"

"A couple of centimeters per minute. It's too small to pack a real
power unit."

"Give it five minutes, just to make sure it isn't a building block."

"Ten centimeters wouldn't give you a whole building block."

"A sample from that far inside one would tell me what I want to know.
You rock-chippers don't seem to think that archaeology is a science
yet. Let me have that first core, too." Mitsuitei looked confident
to the point of being cocky, and Lampert let the mole burrow on. The
second core came in due time, and the little man set merrily to work
with tiny chips from the two stone cylinders, a pinch of the lowest
soil sample which had been acquired, a small comparison microscope and
a kit full of tiny reagent bottles. Lampert used the time the tests
consumed in reversing the mole and resetting the equipment on a new
spot. By the time the little mechanism had gnawed its way once more to
rock, Mitsuitei was forced to admit that the formation appeared to be
natural.

He did not seem as disheartened by the discovery as might have been
expected. He simply waited for more cores, his narrow face reflecting
nothing but the utter absorption Lampert knew he experienced whenever a
problem arose in his line. In spite of his apparent tendency to jump to
conclusions, Takehiko Mitsuitei was an experienced and respected member
of his profession. Lampert knew enough about his record to be perfectly
willing to accept his instructions for the present.

       *       *       *       *       *

A series of holes was drilled, from the original position toward one of
the "streets" forty yards away from it. After each the archaeologist
admitted with perfect cheerfulness that there was nothing inconsistent
with the idea that the hill was a perfectly natural formation. He still
insisted, however, that the regular lines of trees, reinforced as they
were by the undergrowth pattern, required explanation.

Lampert admitted this, but felt that he knew what the explanation would
be. After all, volcanic residue is more than likely to contain the
trace elements vegetation requires, even on Viridis.

Finally the time came to get verification--or the opposite. The
flamethrower had to be used this time, and for several minutes clouds
of steam swirled about the men as its blue-white tongue fought the
sappy, rain-soaked undergrowth. Then the mole and its controls were
wheeled into place, and the little robot once more nosed its way out of
sight.

"I don't suppose you want any samples above the regular rock level, do
you?" asked Lampert as the machine disappeared.

"I think it would be best if we took them as usual," was the reply.
"For one thing, we should try to learn the depth at which the soil
composition changes--we are at least agreed that it changes in some
manner, after all."

"True enough." The geophysicist set his controls, and the process
continued--a process familiar now to McLaughlin as well as the
scientists, for the guide had caught numerous glimpses of what was
going on while he prowled about the work area on self-imposed guard
duty.

Mitsuitei took the crumbly soil cores as they came, examined them
quickly--they were arriving every few seconds--and filed them in
numbered compartments in a specimen case he had opened. Detailed
stratigraphy would come later. For some time there was no gross
evidence of change in the soil; not, in fact, until his first case had
been filled.

"Can you stop that thing for a moment, Rob?" he asked at this point.
"I don't want to lose track of these, and will have to hold up while I
open a new case."

"All right. I thought you'd want to stop for thought soon anyway."

"Why?"

"Because the mole is nearly four meters down, well below the depth at
which we hit bedrock before, and is still in soil."

"Eh? But--but it's still ordinary soil; none of your volcanic ash."

"Tuff had been eroded out of a lot of the joints in the cliffs. There's
no reason to expect it to be at the same level as the surrounding rock."

"That's true." Mitsuitei paused in thought for a moment. "If we keep
on going straight down, we may just be working into a natural crack,
as you say. Might it not be better to drill several holes within a few
square yards here, to determine whether it is a narrow joint such as
you expect or an actual edge to the rock at this level?"

"Maybe the edge of a roof, eh?" Lampert chuckled, but spoke in a manner
which could give no offense. "I can do better than that. Don't need to
pull up and start over; simply drill horizontally from where we are
now. Shouldn't take long to get dimensions, if that's all you want."
He halted the robot momentarily, and from a compartment in the drum
removed something like a small theodolite mounting. This he set up
on a short tripod over the point where the neck of the mole emerged
from the ground, and set a pointer at right angles to the line of tall
trees. Then he started the digging again.


                                   V

Four starts in as many different directions and twenty minutes of
time showed fairly conclusively that the line of vegetation which had
given rise to the "street" theory was growing along a straight crack,
apparently a fairly ordinary joint, in the limestone. While several
more holes would have to be drilled to prove it, even Mitsuitei was
willing to admit that in all probability the remaining lines would be
found to be over similar cracks.

"You must admit, though, that the regularity of this joint pattern is
pretty unusual," the archaeologist said at length.

"It's far from being unknown," Lampert replied. "I got my first large
taste of it in my student days back on Earth. Fly over the mesa country
in southwestern North America sometime. Most of the joints there are
invisible from a distance, of course; but at the edge of a butte where
weathering is most prominent the blocks have frequently started to
separate, and the thing looks as though it had been put together from
outsize bricks."

"Hmph. Seem to remember something of the sort myself, now that you
mention it. I did some digging in that area, too. I shouldn't have
connected that sort of country with what we have here, though."

"Different meat; same skeleton," replied Lampert.

"But how about this volcanic ash, or mud, or whatever it is, which at
least fills the joints we saw in the cliff? That's not so usual, is it?"

"Not in my experience. But granting the joints and the volcanoes,
there's nothing really surprising about it. Incidentally, we don't know
that this crack we're standing on has the same filling. We'd better
bore down again to make sure. At least we may get some idea of the date
of the volcanic action compared to that of the orogeny that tilted
the block where we're camped. If there's tuff down here too, it will
substantiate the idea that the vulcanism is the older."

"Why? Couldn't ash have settled down here as well as up there at
substantially the same time?"

"It could. But I'd bet a fairly respectable sum that the tuff we saw
in the canyon was from a mud flow, not a fall of airborne ash. That
could hardly have reached the top of the cliffs--actually, the opposite
slope of the mountains, where Sulewayo is working--and this area
simultaneously."

"Maybe from different eruptions? I get the impression that this world
has a slight tendency to produce volcanic fields rather than individual
cones or flows."

"Might be. Chemistry will probably settle that question." During the
latter part of this discussion Lampert had directed the mole once more
downwards, and every half meter of travel another core was added to the
collection. At six and a half meters below the soil the first solid
specimen arrived; the others had been held together only by roots.
This one, however, caused the two scientists to look at each other.
Lampert nodded slowly, with a smile. Mitsuitei gave a shrug, and let an
expression of resignation play over his usually impassive features.

The core was tuff, apparently identical with that in the cliffs to the
east. It even contained fossils.

       *       *       *       *       *

"I guess this whole dig might as well be taken over by the paleontology
department," Lampert commented finally. "I suppose they'll at least
want to compare fossils in the tilted and level strata."

"I suppose so." Mitsuitei was turning the little cylinder over and over
in his hand. "Tell me, Rob, what's this little speck of green?"

"Copper salts of one sort or another, I suppose." Lampert was not
greatly interested. "A lot of secondary minerals form in and under
volcanic detritus. On this world, carbonates like malachite should form
quite readily."

"Why should it form in a regular thread like this?"

"You mean a vein? Hard to tell precisely. Varying rates of water
seepage, varying degrees of oxygen or carbon dioxide penetration,
varying degrees of compactness in the rock where the stuff is formed--"

"I don't mean a vein. This is in a cylindrical body going right through
the core from one side to the other, as though there had been a copper
wire there originally which had been attacked by soil acids."

"Let's see. You're right. It's hardly an ordinary vein, though your
suggestion seems a trifle far fetched. The paleontologists can probably
furnish an idea. Maybe a vine or even a worm buried in the mud flow
acted as the precipitating agent for copper salts in the subsequent
seepage--I've seen beautiful fossils of pyrite which had been formed
that way."

"But this shows no trace of structure, except for its exterior shape."

"Isn't a really well preserved structure the exception rather than the
rule in fossils?"

"I suppose so. Still, I'd like to know just how far, and which way,
this green thread goes. I'd also like to know whether there are dilute
copper deposits spread through this rock, which could be concentrated
in the way you suggest."

"The first could be learned by taking enough cores. The other would
call for some very careful analysis of samples which had been selected
with a very sedulous eye kept on the stratigraphy. You know that; you
must have done that sort of thing looking for carbon-fourteen samples,
at times."

"Yes, I see that. Could you make such analyses here?"

"No, except for the mere presence of copper. The cores would have to
go back to a well equipped lab. Still, if you want to get them, it's
all right with me. Problems were made to be solved. I'll admit this
one doesn't seem very exciting to me, but I can use your data after
you finish for work of my own. You should wind up with material for a
pretty complete geochemical picture of this neighborhood. Shall I get
the cores for you?"

"Yes, please."

"Silly question. All right." The mole was drawn up a short distance,
and sent questing downward once more at an angle to the original shaft,
branching off a short distance above the level from which the copper
deposit had come. Again and again the process was repeated, each time
at a slightly different bearing from the central hole; and Mitsuitei
examined each core for traces of green. At last he found it, piercing
the little cylinder of rock as the other had done; and then, at his
suggestion, Lampert reset the mole to get a sample in the opposite
direction from the one which had furnished the new specimen.

       *       *       *       *       *

This also checked positive; and four more samples, taken along the same
line at various distances, all did the same.

Apparently the line of green extended for some distance, about parallel
both to the surface of the ground and the trend of the joint in which
it was buried. Mitsuitei was radiant.

"I'm going down to that level if I have to come back with an expedition
of my own! If that's a fossil worm, it's worth getting the whole length
anyway--but I don't believe it is. I--"

"That will take a lot of time, you know," Lampert pointed out mildly.

"Certainly I know! Even if I use your fast excavator down to the tuff
level, I'll have to do detail work from then on. What of it?"

"Well, the others may have jobs they want to do--"

"Then they can do them! What are we here for, anyway? I thought it
was to investigate the past of this planet! Ndomi and Hans are doing
that their own way right now. Why can't I? I'm an archaeologist, and I
came along to do any archaeological work that presented itself to do;
this is the only thing of the sort anyone's seen so far. I know what
you're thinking. Maybe you're partly right. I certainly won't bet any
money that this thread of green is a fossil telephone wire; but it's as
likely to be that as anything else you've suggested, and I'm going down
to that level and sift the whole volume. Hans and Ndomi can have any
fossils I find if that will make you happier--and if one of them says
he has no use for fossils he didn't dig himself, I'll make him eat his
words. I can identify, locate and report on anything that turns up in a
rock as well as any of those jigsaw-puzzle people; and I can do it in
mud, too, which is more than any of them could manage."

"Don't get hot under the collar. If you can help it on this planet.
You sound as though one of the boys had been giving you a lecture on
the importance of knowing what strata a given series of specimens
represent."

"Not one of our boys--they have a little more sense. But there was
a young paleontologist when I was covering the Antares worlds whose
memory still makes my blood pressure go up. Never mind me; that's not
important. But I want to make this dig."

"It will tie up machines, however freely we can spare time," Lampert
said slowly. "I'll tell you: how about this? We spend the rest of
the day getting cores from other points along these cracks. For one
thing, we ought to know more about the structure of the hill, and for
another, we might find more of your 'wires.' After all, the chance of
our hitting the only one around is pretty remote. I can't quite see a
single dropped piece of copper wire showing up in the first two days of
a project like this."

"I neither said nor implied that this should be the only piece. I don't
doubt for a moment that there are others, whether they are wires or
worms."

"Sorry. Well, we take these cores back to camp this evening, together
with any others we find of the same sort, and let Hans and Ndomi
look them over. If they don't turn out to be something that the boys
recognize and can classify right off the bat, we come back tomorrow
with all the digging machinery you want, and dig until you either
find all you want, satisfy yourself that there's nothing here or find
something which obviously requires more specialized attention than we
can give it. All right?"

"Nothing could be fairer. Let's go!"

       *       *       *       *       *

The discussion in camp that evening was animated beyond anything the
guide had heard. His original estimate of these men as relatively
quiet specimens underwent a sharp revision. Mitsuitei's report of
the day's activity at his site had, it is true, been delivered quite
calmly; but from then on matters grew progressively livelier. This was
not caused by opposition to the archaeologist's plans. The others were
all in favor of remaining, for their own reasons. However, the question
of just what was likely to be found gave rise to much rather barbed
comment on Sulewayo's part. "I don't see how you can expect to find any
trace of civilized work here," he said flatly at one point. "The animal
and plant life of this planet is at a stage of evolution corresponding
to something like Earth's Pennsylvanian age, when the amphibians were
the highest known forms of life. I'm not saying that there couldn't
be such a thing as an intelligent amphibian. But I do say that the
normal set of evolutionary forces which, on both Earth and Viridis,
produced creatures of the amphibian pattern could have done that _or_
produced an intelligent fish; not both. If the latter ever evolved, it
failed; for the amphibians--pardon me, amphibids--are here. To get an
intelligent amphibid on this world will--or would, if the sun were to
last long enough--require another orogenic period with the accompanying
climatic changes. Then you'd stand a considerably higher chance of
getting reptiles instead, if the comparative work done on over four
hundred planets carries any meaning."

"I don't doubt the value of the work at all. You are very probably
correct. It did not occur to me to expect remains of intelligent
amphibians. I saw no reason to pre-suppose that anything in the way
of artifacts which I might find would necessarily be native to this
planet."

"You think there were other visitors from outside the Beta Librae
system?"

"The possibility certainly exists. Here we are."

"But for Pete's sake! Do you really expect that they stayed long enough
to build a city, or do you think you have the remains of a camp like
ours, or what?"

"I don't think anything. It has been suggested that such people did
come, and stayed long enough to--"

"And you think you've found them."

"I think nothing, except that I have found, with Rob's help, something
which neither his professional knowledge, nor mine, nor even yours, is
able to explain; and I think an explanation is desirable. I hope you
won't consider me discourteous for pointing out that each time you have
tried to accuse me of jumping to conclusions, you have been able to
do so only by jumping to some yourself. I might further add that the
suggestion that this planet had been stocked with its present supply
of life types by visitors from space was advanced by a paleontologist,
not by one of my colleagues. I gather he could not understand how life
could evolve to the state it shows in the thirty-odd million years
that the planet seems to have been solid. I neither support nor deride
the idea; I simply want to gather data, in an attempt to explain a
much simpler question--why are narrow threads of copper compounds to
be found every few feet in the volcanic tuff filling the joints in
a certain limestone hill, and why are those threads always nearly
horizontal? You and Hans say they are not organic fossils, and I
accept your conclusion. Rob says that there is no copper in that rock,
detectable with his equipment, except within a few millimeters of the
green threads. I say nothing except that I have never seen such a thing
before. Under the circumstances, I fail to understand where you get
the idea that I think there is a city built by the people who stocked
this world thirty million years ago buried under that hill. I know I
said 'city' when I first saw it, and I still think I was justified in
the opinion; I have now seen evidence which causes me to admit that
the vegetation pattern was not caused by artificial structures, and
I dismiss the original hypothesis. I still want to dig there, and in
accordance with Rob's agreement I am going to dig there, with the
assistance of anyone who chooses to help. I know you want to go back to
your set of leg bones in the cliff, and have no objection to your doing
so. Even I can now see, on the basis of your description, that you are
uncovering the fossil of a land animal; and I agree that it is of great
importance to get it out intact, if possible. But if I can see the
importance and even the nature of your work, why can't you do the same
for mine?" The little man was leaning forward and staring intensely
into Sulewayo's face by the time he finished this harangue, and Ndomi
once more felt a trifle ashamed of himself. Lampert, however, saved him
the need of formulating an apology.

       *       *       *       *       *

"I'm sure Ndomi didn't mean to ridicule your work in any way, Take,"
he said. "We all realize perfectly that an underground phenomenon
which cannot be explained at sight either by geology, paleontology or
archaeology is something which requires investigation. I imagine that
the best plan will be for String and me to go with you tomorrow, while
the others continue their stone-cutting. Hans, just how far along are
you, anyway?"

The older paleontologist thought for a moment.

"We don't really know," he said at last. "Of course, we aren't trying
to get the individual bones completely free of the matrix; that
will take somebody months or years. We're uncovering just enough to
determine the extent of the specimen, so we can take it all out in one
block--or more, of course, if it's too big. So far we can only guess at
how big it is. We've uncovered with certainty two feet, and gone about
half a meter along one of the attached legs. They seem to be extending
straight back into the cliff, so in effect we're cutting a tunnel
beside the thing. Assuming it had two main leg sections, as most of the
present animals on both Earth and Viridis appear to have, we're about
halfway between knee and hip joint. Of course, it might turn out to
be the Viridian equivalent of a horse or chicken. In that case, we're
about half way between ankle and knee. We certainly have several feet
yet to penetrate before we can outline the whole block, assuming that
the specimen is essentially complete. Several days, I would guess."

"Can you use any sort of power apparatus for any of your cuts?"

"I don't like to, on general principles, but--yes, we could, with
actually very little risk. If you have some sort of rock saw whose
cutting part can get fine control, I'd be willing to use it for parts
of the tunnel away from the actual specimen."

"I have. We'll take you up there first thing in the morning, and I'll
go down with you and show you how to use it before going on with Take
and String."

"Who holds the 'copter in place while you climb down the ladder, give
your lesson and come back?" asked the guide.

"Hmph. I forgot about that. All right, I'll break out the machinery and
give the lesson right now." He got up and strode to the helicopter.
McLaughlin covered him from the fence to the aircraft, but nothing
dangerous appeared. The geophysicist disappeared inside, and returned
a moment later with a compact metal case under his arm. The guide
holstered his weapon as the gate in the fence closed once more....

Actually, the Felodon was miles downstream. It had spent the day in its
chosen lair, apparently indifferent to the doings of the men a few
hundred yards away. With the coming of darkness--real darkness this
time, for the rain clouds cut off both the moonlight and the night
glow from the upper atmosphere--it had emerged, hunted, killed and fed
as before, apparently unhampered by the lack of light. By midnight it
was back in the same lair, paunch distended, as close to sleep as its
coldblooded kind ever came.


                                  VI

The rain was still falling when the clouds lightened once more to
the rising sun. Lampert was getting used to navigating the canyon by
radar, and was an excellent pilot anyway; so he did not have too much
trouble in locating the shelf where Sulewayo and Krendall had been
working. Getting the men down to it was not particularly difficult,
though rather nerve-racking. Krendall went first, unburdened except for
his personal equipment. Then he steadied the ladder for Sulewayo who
had the cutter strapped across his shoulders. The steadying hand was
needed. Climbing down a rope ladder when loaded "top-heavy" can be an
extremely awkward bit of activity. Had the pilot above been any less
capable, it would probably have been impossible.

The ledge was wet, but fortunately not particularly slippery. The men
set their equipment on the ground at the point where their cut entered
the crack in the cliff, and without delay set to work. The tunnel was
deep enough now to shelter the one actually cutting from the rain, so
at first they took turns at this operation.

The cutting machine Lampert had provided was a sort of diamond-toothed
chain saw capable of a two-meter extension. Ordinarily it was not the
sort of thing a paleontologist would consider using so close to a
specimen; but the men were fairly sure by now of the general extent
of the thing they were uncovering. Even so, they used the saw only on
the side of their tunnel away from the visible remains. They speedily
widened the passage enough to permit them both to get inside and work
on the face of the exposed material; but they still used hand tools
whenever there was any suspicion that a bone might be about to appear.
Work proceeded several times as fast as it had the day before.

They tried cutting another tunnel on the opposite side of the fossil,
but this proved rather awkward. The creature was close to this side of
the crack, and they had to cut limestone as well as the softer tuff.
The saw proved capable of handling this--it would have handled granite
without trouble--but went a little more slowly. Eventually, however,
the two men were working on opposite sides of the fossil, each in a
tunnel extending some two meters into the cliff face.

Half a day's work uncovered the leg bones sufficiently to show that
Krendall's first idea had been right. There were only the two major
joints, each a trifle shorter than the corresponding parts of the
human skeleton. The lower leg was single rather than double, however;
knee and ankle both consisted of ball-and-socket joints; and with this
fact determined the men paused for thought.

"Now why," mused Krendall aloud, "should any sort of creature need that
articulation?"

"Could that foot be a hand instead?" asked Sulewayo.

Of course, questions like that should have awaited the results of
detailed examination in a laboratory. Equally of course, the two men
proceeded to clear one of the "feet" a little more thoroughly in order
to find out for themselves. The answer was not helpful, though.

"He might have picked up a twig with it, but he couldn't have held it
any more tightly than I can in my toes," was Krendall's verdict. "It's
a bigger and flatter foot than ours. But it's a foot--nothing more."

"Maybe a swimming organ on the side?" suggested Sulewayo cautiously.

"Seems doubtful. If that joint evolved for such a purpose, I should
think there'd be a corresponding modification in the foot bones,
too--say a flattening such as you see in the paddles of some of the
Mesozoic sea reptiles of Earth."

"Reasonable."

"But not necessarily right. That I admit. Anything else strike you?"

"Yes, though it makes the joints still more unbelievable."

"What?"

"The foot itself. Unless some rather remarkable distortion has
occurred, it had both longitudinal and transverse arches, like yours
and mine--which suggests strongly that this thing's ancestors had
been walking erect on two legs for some hundreds of thousands of
generations." Krendall raised his eyebrows at this, and silently
examined the bony structure before them for several minutes.

"I--hadn't--spotted--that," he said slowly. He looked in silence for
several more seconds. Then the two men, moved by a single thought, went
to the other end of the exposed leg and began to clear the hip joint
and pelvic region. They worked almost in silence, understanding each
other perfectly, like an experienced surgical team; and gradually the
equivalent of a pelvic girdle and lower end of a spinal column were
cleared sufficiently to show their general nature.

It was at this point that the helicopter returned; but neither man
noticed the fact until McLaughlin had called several times from the
open ladder hatch. They climbed silently and thoughtfully up to the
flyer; but Mitsuitei's first question started the talk flowing.

It did not end for a long, long time.

       *       *       *       *       *

Krendall, with difficulty, held interruptions of his more volatile
companion.

"There can be only the slightest doubt that this thing we're uncovering
walked erect on two legs," he reported. "The feet; the way the
pelvis is modified to _support_ internal organs; the fusing of the
lowest vertebrae with the pelvic girdle to form a weight carrying
foundation--they all point the same way. The only thing hard to
understand is the knee and ankle joints. If we had them, it would be
virtually impossible for us to hold our legs rigid. Perhaps some really
remarkable musculature--"

"Or a cartilage structure which has not been preserved," cut in
Sulewayo.

"Or some such thing as that, would explain it. I don't know. The
creature is good for several Ph.D. theses just as it lies--and probably
an equal number of nervous collapses when we get it out."

"I find myself strongly desirous of seeing its skull," remarked
Lampert. Sulewayo glanced at him sharply.

"You, too?" asked the young paleontologist. "I was hoping I was the
only one crazy enough to have thought of that." Mitsuitei smiled
openly, an almost unheard-of act for him. He said nothing for a moment,
but everyone saw him; and even McLaughlin understood the thought. After
a sufficiently long pause, he asked a question.

"Have you uncovered enough of this creature's structure to guess at any
evolutionary connection--or lack of it--with the amphibids we already
know on this world?"

"I'd hate to take any oaths," replied Krendall. "The legs, which we've
seen most of, are different in detail; but they at least correspond in
general with what we find here. The only really significant point there
would be the single shin-bone. In that it resembles Viridian land life
in general--these animals don't have the separate tibia and fibula
characteristic of the usual run of Earthly land vertebrates. It really
proves nothing about what we're all thinking, of course."

"I am tempted to work with you gentlemen tomorrow," muttered the
archaeologist.

"Why? Didn't your investigation pan out?"

"It is harder for me to say than for you, so far. To dig a pit, big
enough not only to work in but to cover a useful amount of ground, in
a driving rain, is quite a job even with Rob's machines--which I would
never use were I not sure that there is nothing of importance above
the limestone level. I have gotten down to the rock over an area three
meters square, which is very good going; but I shall undoubtedly find
the pit full of water tomorrow, as we have not yet improvised a really
satisfactory drainage system. I cannot--or at least will not--use
machines inside the crack in the limestone; so it will be some time
before I get down to our mysterious green threads."

"Then it would seem that the best we can do is go on as we have,"
said Lampert. "The only change might be if one more man were to help
at Take's dig. But I don't suppose either Hans or Ndomi would care to
leave his own job at the moment, and actually there's not much more
to do at the hill which can be done by anyone but Take himself. I'll
continue to help him as long as it's a question of moving mud, but
after that he'll have to do his own sifting. String is automatically on
guard duty at the hill, so there's not much change we can make. Though
I must say I haven't seen anything dangerous yet, in that jungle."

"Those animals are like crows," remarked the guide. "We used to have
'em on the farm, back on Earth. They'd be all over a freshly planted
field, while no one was around. Come out yelling--they don't move;
come out with a gun, and they're gone--unless you'd happened to forget
to load it; then they sat and laughed at you. If you're suggesting,
Doctor, that I should relax the guard duty and lend a hand with
digging, I veto the idea--and not because I'm afraid of getting my
hands dirty."

       *       *       *       *       *

"I won't say I didn't have some such thought, but I accept your
ruling," smiled Lampert. There was silence for a moment; then Krendall
reverted to the earlier subject.

"You know," he said, "if this thing we've found does turn out to have
been intelligent, it will hardly solve any of the existing problems
about Viridis."

"Why not?" asked Sulewayo in some surprise.

"We still won't know whether it's native to the planet or not, unless
we can establish a relatively complete evolutionary sequence leading
to this form. If we do that, the question of speed of evolution here
gets worse than ever; if we don't no one will be sure whether or not we
ought to look for buried spaceports or send out expeditions to find
the planet they might have come from."

"The latter would be something of a waste of time," remarked
McLaughlin. "Hunting one planet in the galaxy is like hunting one
log of wood on Viridis." No one contradicted this. All had seen the
galactic star clouds from outside planetary atmosphere.

"It seems to me, speaking as an amateur in your fields, gentlemen,"
said Mitsuitei, "that the mere discovery of an intelligent creature
in the Viridian fossil deposits would, on the basis of our present
knowledge of the mechanisms of evolution, strongly support the idea
that this world was stocked from others. I realize that our knowledge
_may_ not be sufficient to justify us in that conclusion. But it is
_certainly_ not great enough to justify any other."

"You seem to have something there, Take," admitted Krendall. "If this
thing does turn out to have room for a brain in its skull, I suppose
the next ten conventions of the Interstellar Archaeological Society, or
whatever you call it, will be meeting at Emeraude."

"I shouldn't be at all surprised. So far, my profession and yours have
not overlapped, due to a considerable factor of difference in the time
spans covered. But it is just possible that we would be holding joint
meetings, in the event you describe."

"This meeting is changing from discussion to speculation," Lampert said
drily. "I would be the last to decry the value of imagination; but
actually we are as likely to face the need for entirely new hypotheses
as the result of our work here, as to find support for any now in
existence. I can speculate with the best of you, but for goodness sake
let's not take any speculation too seriously. I don't _really_ believe
that some big-headed descendants of Ndomi's fossil are listening in on
me right now!"

Even Sulewayo admitted that this was rather unlikely, and the
conversation turned to other matters until darkness fell.

No one had trouble sleeping. The loud drumming of the rain on the metal
roof meant nothing to field workers with their experience. If anything,
the sound was soothing, giving a perpetual reminder that there was a
roof. Such protection is not always available, in that line of work....

The Felodon seemed to have lost its traveling propensity. Once more it
went out into the utter darkness solely to get a meal. It accomplished
this as quickly as ever, though its eyes must have been useless and the
hiss and rumble of falling water drowned and buried any sounds which
would have been useful in tracking. Back in the same lair, full-fed, it
drowsed once more.


                                  VII

Mitsuitei had been almost right in his prediction that the pit would be
full of water. Only the fact that the land sloped a trifle--they were
not right on top of the little hill--had saved it. As it was, several
feet of water were in the bottom, and a good deal of mud had washed in
from the two sides facing the edges of the crack. The other two, much
better braced by deep-reaching roots, had held firm.

After some thought, Lampert used the little robot again. He started
it at the bottom of the pit on the downhill side and drove almost
horizontally toward the river. The two hundred meters of "neck"
permitted the mole to emerge from the slope farther down. When it was
withdrawn, a small drain hole was obtained. Several more of these were
drilled, and the pit lost its water fairly rapidly.

There was still the problem of getting into the crack itself, which
of course would involve digging below the level of the drain holes.
Lampert, using the same excavator which had made the pit itself,
finally provided a fair solution by digging a set of ditches around the
larger hole; and since the opening itself was quite well protected by
over-hanging trees, Mitsuitei had only drainage from the surrounding
soil to contend with.

Two hours after arriving, therefore, he had a relatively clear working
space. The bottom of the pit was limestone, exposed by the complete
removal of the overlying soil, some three meters square. Across it
ran the crack, a trifle less than a meter wide, still packed with
dirt. Everything was muddy--limestone, projecting roots, and Mitsuitei
himself. A slender log with branches cut to ten-centimeter stubs leaned
against one corner, forming a rough ladder and giving entrance and
egress to and from the site.

The machinery which had done the original digging was at one side.
Mitsuitei did not expect to need it again. He was now equipped with a
hand shovel, and seemed about to use it. Lampert, standing at the edge
of the pit, felt the incongruity, but managed not to laugh.

"Are you sure there's nothing I can do down there with you?" he asked.

"I'm afraid not. From now on I want every bit of dirt to pass under my
own eyes."

"Are you going to try to throw it all up here as you finish?"

"No. That's the purpose of the extra pit area down here. I can get a
long way down the joint, simply heaping the material on the rock. It's
damp enough to pile quite steeply, too."

"How far down do you think you can get? The crack's rather narrow to
work in, and you have three and a half meters to go before you hit
tuff. That's going to be rough shoveling. I still think you could use
the machine safely for a little way further, at least."

"No doubt I could, but I'm not going to. There's one thing I might use,
though. If you have another of those saws, such as the bonemen are
using up on the cliff, I could widen this crack as I go--cut steps, in
fact, to help get the mud up to this level when I'm further down."

"That's a good thought, but I don't have any other. If you really get
far enough down to need it, though, I could fly up to get it. They were
going to shift over to hand labor anyway."

"All right. Of course, it will be some time before I get that deep
anyway; maybe I won't need it today." He bent to his work.

"But what do I do?" asked Lampert. "I can't go off to attend to my own
projects, because String has to stay here to guard you. I can't get to
the site where the others are working because I can't land there. I
can't sit in the helicopter and twiddle my thumbs because I'll go crazy
before the day is over." Mitsuitei straightened once more, and thought
briefly.

"Is there nothing in the geophysical line you could do within sight of
this pit?" he asked finally. "The saw and digging machine are not the
only apparatus you brought."

"That's true. I brought some seismic gear, though I didn't plan to use
it quite like this. I might map the formations under this hill. The
information will be usable, I should think, and the joints will give
quite a calibrating job. It will keep me busy, anyway."

"Just a minute!" Mitsuitei looked a trifle perturbed. "Does that mean
you're going to set off explosives around here? I want the sides of
this pit held up by something better than roots, if you do."

       *       *       *       *       *

Lampert chuckled. "No explosives," he said. "This is a nice little
gadget with a robot like the core sampler. It puts out waves of any
type desired from any depth down to two hundred fifty meters--a sort of
subterranean sonar. You'll never know it's working. The wave amplitude
isn't enough to feel." He turned toward the helicopter on the river
bank below, and was starting to walk toward it when McLaughlin
interrupted. The guide had heard the conversation, and his question was
purely rhetorical.

"You weren't planning to walk down to the flyer alone, were you,
Doctor?"

"Well, yes, as a matter of fact. After all, I won't be working; I can
keep my eyes open as I go. You can see me for the greater part of the
journey from here, too."

Rather to his surprise the guide approved this argument, after a
moment's thought.

"All right. But please keep your gun in your hand as well as your head
on a swivel. I'd prefer to have Dr. Mitsuitei come down with us so we
could stay together, but I know how he'd react to the interruption, and
I realize you're not a kid. Just be careful."

Lampert promised; and the guide's manner had impressed him to the point
where he was almost afraid to make the return journey, after reaching
the flyer and packing his new equipment. He was rather surprised to get
back to the site without being attacked, and McLaughlin's very evident
relief at seeing him did nothing to ease his feelings.

He began to set up the machinery. This consisted of an assembly very
similar to the drilling mole--a small delving robot drawing a slender
tail behind it, the tail wound on a drum which surrounded the control
unit. A dozen smaller cylinders reposed in attached clips.

"The attached borer," Lampert explained to the guide, "goes down
to any depth I set, up to two hundred fifty meters. It can produce
any of the three normal types of earthquake wave, singly or in any
combination, with sufficient intensity to be detected at a range of
over two kilometers in reasonably well-conducting rock. The small
cylinders are detectors, equipped not only to receive and analyze the
wave coming through the ground but to measure electronically their
location with respect to each other and the main station. I can use as
many of them as I please, up to the full dozen; but they can be planted
only a little way below the surface. There exists equipment for getting
readings at depths comparable to that of the transmitter, but I don't
have it. As it stands, by spotting the receivers carefully I can get a
pretty good picture of the formations for a radius of a kilometer and a
depth even greater with ten minutes measuring--and ten hours computing."

"How far out do you plan to place these receivers?" the guide asked
pointedly.

"Well--I hadn't made a detailed plan of that. I'd rather like to have
them in radiating lines of three, the lines spreading about fifteen
degrees, and the individual cylinders about two hundred meters apart."

"And just how were you going to place them? I gather that someone has
to walk the best part of four kilometers--or do these things fly, in
addition to their other abilities?"

"Er--someone walks. I thought perhaps, since you don't like the idea
of my going alone through the jungle, that I might stand guard over
Take in the pit while you set them out."

"Hmm." The guide did not explode, to Lampert's relief. It had not
occurred to the scientist that the job of wandering around a hole in
the ground waiting for animals which never came might get a little
boring to a man of McLaughlin's background. "Let's go over first
and see how Dr. Mitsuitei is getting along. I guess you could stand
over him with a gun for half an hour. Of course, the cover runs
dangerously close to the pit. Maybe we'd better burn it off to a
safer distance--still, I guess that won't be necessary. You can stand
out here where it's relatively clear, and see all the approaches to
the pit. Something might jump in without your having time to hit it,
and you'd at least see it and could get there fast enough to do any
shooting necessary."

They approached the hole and looked in. Mitsuitei was working busily.
A fair quantity of earth lay spread on the rock, and some two thirds
of the length of the crack had been excavated to a depth of perhaps
a quarter of a meter. The geophysicist attracted the little man's
attention and told him of the plan; Mitsuitei nodded and bent once more
to his work.

The Felodon was becoming restless. It could hardly be hungry as yet;
but it was on its feet, snarling silently as it had when the helicopter
first entered its ken. For perhaps a minute it stood; then, with
the same air of determination it had shown days before and scores of
kilometers away, it began to thread its way through the underbrush
toward the river--and the digging site.

       *       *       *       *       *

"I'll stand where you suggested, and never take my eyes off the pit,"
Lampert promised.

"Then I'll come back to find you missing," replied the guide. "You're
guarding yourself too, remember. Don't keep your eyes on anything. Keep
them moving."

He finished distributing the little cylinders in the various pockets
of his outer clothing, and moved off in the direction Lampert had
indicated. He looked back frequently, but each time saw the scientist
alert. When the underbrush finally cut off the view, he refused to
worry too much.

Actually, McLaughlin had gone to considerable pains to make the jungles
of Viridis sound more dangerous than they really are. His conscious
motive was to make the inexperienced members of the party alert enough
for their own safety. It was quite true that a man could be killed in
quite a variety of ways in those rain forests. There was a distinct
possibility, however, that he also wanted to impress them with the
importance of his services.

He did not, therefore, suffer much from anxiety during his walk, though
on the other hand he wasted no time. He had, of course, only a rough
idea of the distance he had traveled, though he was able to keep his
direction with a small impulse-compass tuned to the seismic apparatus
and forming part of its regular equipment.

He dropped three of the cylinders at the required intervals, as nearly
as he could guess, forcing each a little way into the ground as Lampert
had shown him; then he turned at right angles, walked what he hoped was
the right distance and started back toward the site, planting equipment
as he went. Out again, in again; and the last of the dozen tubes was in
the ground.

Mitsuitei's shovel scraped deeper.

Lampert, glancing up and around every few seconds, made minute
adjustments to the controls of his seismic apparatus. Its little mole
robot had started on its downward trip.

The Felodon lurked thirty yards from the point where Lampert was
standing, protected from his sight by the undergrowth and by one of the
piles of dirt thrown up by the machine which had dug the pit. It seemed
to be looking through the soil at the spot where the man was. The snarl
was still on its face, but no muscle moved in its long body. It had
been there for minutes without moving; it had frozen similarly when
McLaughlin had passed it on his way out. Now it simply stood and waited.

On a cliffside kilometers away, Ndomi Sulewayo gave utterance to the
first profanity Krendall had ever heard him use. They were on opposite
sides of the block containing the fossil, so neither could see the
other. Krendall, naturally, asked what was wrong.

"Don't tell me a bug got through one of these suits!"

"Worse, if possible. I told you this foreleg--" both had been carefully
avoiding the use of such words as "arms"--"was sticking out sideways,
so that I was afraid we might have cut off part of it in digging the
tunnel."

Krendall nodded. "I remember. Did we?"

"I don't know."

"Eh? How come? I should think there'd be no doubt, one way or the
other, if you have that much of the limb clear."

"Well, I haven't. I got as far as the bone goes--and right there I run
out of tuff and into the limestone. If there's anything more, it's in
an entirely different kind of rock, which is a trifle unlikely; but I'm
going to have to check the blocks we cut from this part of the tunnel
in order to make sure, and I don't look forward to the job at all."
Krendall, properly sympathetic, came around to Sulewayo's side to look,
and agreed that the search was necessary. The bone the younger man had
been clearing ended in a joint of the type they had come to regard as
typical of the creature's limbs; and this had occurred almost exactly
at the surface they had left when first outlining the block with the
saw.

Sulewayo, with a grunt of disgust, dropped his tools and went out into
the rain, where the blocks cut from the cliff had been piled; Krendall,
nobly sacrificing his personal inclinations, went along with him.

       *       *       *       *       *

The search lasted for a long time; for a long time, in fact, after it
became evident that it was going to be useless, for the chance of a
perfect specimen is not easily thrown away. Finally, however, Krendall
straightened up with a sigh.

"I guess we'll have to be satisfied with a restoration on one side," he
said wearily. "I hope someone fifty years from now doesn't find another
and discover that it's a sort of vertebrate fiddler crab, with one
fore-limb ending in a paw or claw something like five times the size of
the one on the other."

Sulewayo gave a gloomy assent, and the two went back to work in their
respective tunnels.

Lampert saw McLaughlin the instant the underbrush made it possible, a
fact which the guide later admitted was to the scientist's credit. He
had, of course, been eagerly awaiting that return, for the transmitter
was down to its first set depth and awaiting only the word that all
receivers were in place. He called eagerly the moment the guide came
within earshot.

"Everything down?" McLaughlin nodded.

"Everything down, as nearly as I could tell the way you said. How long
will the readings take?"

"Only a few minutes. I'll take a couple of calibration shots from ten,
fifteen and twenty meters' depth; then ones at fifty, a hundred and so
on down as far as the mole will go. The shooting takes practically no
time. It's the drilling that will hold us up."

"What then?"

"Well," Lampert smiled, "after that the usual procedure is to pick up
the receivers and place them in a similar pattern in a new direction.
If the field crew doesn't go on strike, we take the whole circle about
the transmitter."

"I was afraid of that," grunted McLaughlin, as he stopped by the
machine. "Well, let's go." The two men bent over the controls in a
silence broken only by the scraping of Mitsuitei's shovel a dozen
meters away. Lampert pressed his shot button, and a light on the panel
flashed white momentarily. Below their feet, unfelt, the pulse of sound
energy raced outward, echoing from the walls of deepstriking joints,
from the boundaries between rocks of differing densities or elastic
constants, from the walls of caverns deep in the limestone; some tiny
portion of the energy from time to time encountering and affecting one
of the tiny receivers McLaughlin had buried.

As each receiver gathered its bit of data, it retransmitted the
information to the master unit; and everything was recorded on a
single sheet as the milliseconds sped by. Long before a full second
had passed, the first of the pulses had damped out as heat energy,
and enough had been transmitted for the machine to obtain an adequate
averaging record. The light blinked out again. Lampert nodded in
satisfaction, and sent the mole downward once more.

"Look, good. Now the next set," he remarked.

       *       *       *       *       *

As that pulse of seismic energy went forth, the Felodon rose to its
full height, almost showing itself over the pile of dirt which was now
its sole protection from the view of the men. The snarl on its face
seemed to grow fiercer, if that were possible. For just an instant it
seemed torn by conflicting desires. But that was for just an instant;
any tendency to flee was smothered before it could take full form.
There were two men now to worry about, and correspondingly less chance
for the opportunity it had been awaiting. But the opportunity came. For
just a moment the guide looked down at the panel which was absorbing
Lampert's full attention. In that moment a green-and-lavender streak
flowed over the heap of soil in a single leap and vanished into the
pit. It must have been timed and guided by the mysterious sense
McLaughlin had mentioned. It could see none of the men when it leaped,
yet it timed the act for the moment none were looking, and landed
directly on Mitsuitei.

The little archaeologist never knew what hit him. He died without
a sound, and the killer, as though nothing lived anywhere in the
neighborhood, settled down to its meal.

In this it must have been disappointed. The chemicals in the clothing
designed to repel Viridian insects were equally obnoxious to the
carnivore, and it made no serious attempt to get through them. However,
not all of the body was protected in this way....

A second pulse went from the buried transmitter, and then a third,
each from a point a few meters deeper than the last. Lampert's
attention, of course, was centered on his controls. McLaughlin's eyes
were once more sweeping restlessly over the surrounding landscape. Both
heard the sounds coming from the pit, but neither interpreted them
as anything more than the scraping of Mitsuitei's shovel. Neither,
of course, considered them consciously. Their attention was finally
attracted by something decidedly more noticeable.

The Felodon did not--or could not?--remain at its meal for more than a
few moments. Its apparent indifference to the other men changed once
more to what seemed like an internal struggle. An observer would have
been sure, up to now, that it was using its peculiar sense to avoid the
sight of men with guns; but that hypothesis failed now.

As Lampert started the mole robot downward once more, the Felodon
leaped out of the pit toward the two men--regardless of the fact that
McLaughlin was facing toward it.


                                 VIII

McLaughlin saw the fanged head emerge, and his reflexes took over
instantly. A streak of flame passed beside the leaping carnivore,
exploding into a white-hot blossom of blazing gas as it contacted the
pile of dirt on the far side of the pit. The guide ducked and rolled
frantically sideward as another spring carried the creature toward
him. Claws raked the air past his shoulder, and he fired again before
the roll was complete and without any sort of aim.

Men and beast alike were spattered with white-hot droplets of metal
from the seismic recorder as the second shot caught it squarely; and
this seemed to be enough for the carnivore. Its next leap was away
from the men instead of toward them. A geyser of steam and mud erupted
beside it as Lampert finally got his weapon into action, and before the
vapor had been beaten down once more by the rain the animal was out
of sight behind the undergrowth. Both men sent several shots in the
direction of the crackling bushes, but accomplished nothing except the
felling of a tree or two and the starting of a bonfire which failed to
make any headway against the rain.

Convinced that the Felodon had gone, the men ran to the pit. Lampert
did not even take time out to glance at the wreckage of his equipment.
There was just enough distance to cover to let each one realize that
he had no idea how long the carnivore had been inside, and what the
"scraping" sound might have been. Both slowed down as they approached
the edge, not relishing what they expected to see. But this did not
prove to be what they had expected. McLaughlin's face, already grim,
turned gray as he saw that his first shot had not merely missed the
animal at which it was aimed.

The bolt had struck the pile of dirt which had been left by the
digging machinery at the far lip of the pit, and scattered most of
it to the four winds. Perhaps half a ton had slid back into the hole
from which it had originally been removed. There was no telling, from
above, what the Felodon had done to Mitsuitei. The upper half of the
archaeologist's body was buried completely, and the rest so liberally
sprinkled with dirt that it was not at once identifiable.

The guide, using language strange even to the widely-traveled Lampert,
leaped the three meters downward without bothering to use the ladder,
seized a projecting leg and tried to draw the little man clear of the
soil. Lampert, equally aware of the possible value of time but feeling
that he would do little good with a broken leg, made the descent in the
normal manner.

By the time he reached the bottom, McLaughlin had succeeded in dragging
Mitsuitei almost completely clear. Lampert started forward to clear
the mud from the still hidden face; then he stopped, and his stomach
abruptly heaved, as he realized that the face was not hidden.

It was gone.

Mitsuitei had removed the head-gear and gloves from his protective
suit for the normal reason--to see and manipulate better. The exposed
head and hands had formed the Felodon's hasty meal.

       *       *       *       *       *

The paleontologists saw the helicopter approaching this time, for they
were working outside the tunnel. Between them on the ledge lay a block
of stone some five feet long, two high and four wide--over two tons
of material, all told, which had been worked out of the hole rather
ingeniously by the men. Partial undercuts had been made, rollers worked
out of stone by the cutter placed underneath, and the undercutting
completed along a plane which sloped slightly upward into the tunnel.
Of course the block had run off the rollers once it was out in the
open, and the men could no more shift it another centimeter than they
could return to Emeraude without the helicopter; but at least it was
more or less accessible by air. They were chipping waste rock from the
corners when the flyer appeared.

Sulewayo was first up the ladder, unburdened this time. They expected
to have further use for the cutter. He noted that Lampert was alone in
the machine, and promptly asked the question the geophysicist had been
dreading.

"Where's Take? We've found something for him!"

"I'm afraid he won't appreciate it. He was killed a couple of hours ago
by a Felodon." The news silenced even Sulewayo, and the expression on
his junior's face actually startled Krendall when he climbed through
the hatch.

"Ndomi! What in--" Lampert cut in with the same news he had given a
moment before. Krendall reacted similarly; then slowly lowered himself
into a seat.

He did not ask for details. Both men could see that this was not the
time to put such a question to the pilot, though neither realized
then the personal responsibility that Lampert felt over the incident.
Krendall pulled a small fragment of tuff from his pocket, and looked at
it thoughtfully.

Nothing further was said until the helicopter landed once more on the
river near the "city." McLaughlin and the bundle which held what was
left of Takehiko Mitsuitei were waiting on the bank, and were loaded
aboard without a sound.

"It's early. Well take him back to Emeraude tonight, and come back for
your work tomorrow," Lampert said, and lifted into the air without
waiting for agreement.

"All right," replied Krendall, "as long as we come back. I don't think
he'd have wanted us to stop. I'm going to find out about those green
threads of his, too." Lampert nodded in approval. He had already formed
a similar determination. For half an hour they flew on in silence.

The Felodon, half submerged in swamp water a kilometer downstream
from the hill, heard the helicopter hum overhead. It seemed totally
disinterested. For just a moment its fanged head pointed upward, then
settled back again. There was a burn under its jaw, which had been
inflicted by metal spraying from the ruined seismic apparatus. It was
more comfortable to keep it under water....

"What was it you found, Ndomi, that you thought Take would want to
see?" Lampert broke the long silence.

"It was when we were undercutting to get the block out of the tunnel,"
Sulewayo answered. "It's just some more of his green threads, in
the tuff below the fossil. I brought a chunk of the rock showing
them--here." Lampert nodded without taking his main attention from
flying.

"Maybe that fossil of yours was intelligent after all, then," he said.
"It seems to have died under very similar circumstances to Take--just
above a set of those green threads. Maybe it was a member of a party
like ours."

"Maybe. It certainly walked erect. The whole body structure shows that.
If its brain were large enough and it had some sort of manipulating
appendage I'd say it was virtually human--in capacity, that is. It was
more of an amphibian anatomically."

"You have the block out in the open. Haven't you been able to study the
head and limbs?"

"No, damn it." Krendall took over from his junior. "That was the big
disappointment of the whole find. The specimen seems to be perfect
except for missing skull and hands. Not a trace of either."

The helicopter wavered slightly in its path, then steadied as Lampert
forced his attention back to his job. No one said anything for a long
time, but everyone was thinking.

       *       *       *       *       *

Someone else was thinking too, but wasn't keeping his thoughts to
himself. They were being spoken, and virtually dripped with the
thinker's fury.

"You sloppy, lazy parasites! I don't mind being stuck with a job and
a deadline, even if it's a report that's due in only fifty years and
needs about two hundred for a real conclusion. I'd sooner do it all
myself than have some of you loose thinkers butting in! But if I'm to
give my whole attention to it so I can produce something that won't be
laughed at from here to the Magellanic Clouds, how about some of you
watching what goes on on this planet? I didn't know those creatures
were poking around until they began cutting sensor lines! Thirty, the
protective life we've bred on the surface was your idea; why didn't you
put it to work?"

The answering words tried to be soothing.

"Thirty was working--"

"Dreaming, you mean!"

"But I put one of the guardians on the job for him; it stopped the
digging, didn't it?"

"Sure, after a lot of damage had been done. Do _you_ want to come out
in the open and repair my wiring--with those space travelers poking
around? If they find you at it, the Council won't just laugh at us;
they'll excommunicate us and let this new species of intelligence clean
us out. Why did it take so long for the guardian to do anything?"

"Well, I--"

"Well, you were dreaming too, weren't you. Blast it, you're here to do
constructive thinking, not just to entertain yourself. Haven't you any
self-respect? They actually dug out Sixteen!"

"What difference will that make? He's been dead too long to mind it
himself, and anyway his brain and sensor connections were decently
burned."

"But they wouldn't have had to dig much deeper to get someone who's
_not_ dead, would they, Ninety-Five, my young friend? I suppose when
they cut one or two of _your_ sensors you decided it was time to do
something. Don't interrupt! I'm talking! This planet is supposed to
be a quiet place where people can expect to spend a decent number of
centuries at a time thinking, _without_ being disturbed. If you're too
young or too lazy or just too stupid to do any real thinking yourself,
at least you can devote a little time from your casual amusements to
making sure that other people _can_. Shut up! You'll do some thinking
now or find yourself in real trouble! Here's a problem for you to
solve, and see that you solve it!

"You will get my sensors repaired, making sure not only that you're not
caught at the job by these space travelers but also that they don't
realize it's been done. In other words, don't just neatly fill in the
hole they made after you've finished, so they can't help knowing
they're not the only intelligences on this world. I don't know when
they'll be back any better than you do, so you'll have to guess at
your own time limit. You can booby-trap your canyon with landslides or
anything else to keep yourself from being dug out, but if you fail in
either problem and either of us looks likely to be found I personally
guarantee you'll be found in the same shape as Sixteen. Now get to
work, and let me think. If you think you can get help or sympathy from
anyone else on the planet, good luck to you."

A wave of agreement spread along the countless miles of sensor wiring
that extended through Viridis' crust, but Twenty-Five didn't feel or
hear it. He had already taken the myriad of tendrils that terminated
his arms away from the mosaic console that formed the end of the vast
bundles of greenish threads coming through the walls of his cave, and
had settled back in his lounging chair. That report--only fifty years
to have it thought out--his full attention went back to it.