Over a vast horseshoe of towering crags, with a drumming roar, the dark, resistless river rushed in a mass of snowy foam and broken rainbows down into the whirling caldron below.

"The Falls of Utiarity," whispered Pinto, as he guided the boat into a little bend by the bank just above where the terrible downward glide of the river began. Making fast to a tree on shore, the whole party stared across at the most beautiful waterfall on earth, as if they could never see enough of its beauty. Something seemed to give way in Will's brain, and for a long minute he felt as if he were entering a new and strange world. Dim, unearthly images seemed to float before him. He thought of the great white throne in Revelation—the mystic emerald circled by a rainbow and the pavement of a single sapphire-stone. Before him was the beautiful water, sinking into the abyss, yet flowing on forever, while a great rainbow trembled, faded, then came again through the mist and spray like a beautiful spirit walking the waters. With the terror, the rush, and the roar of the crashing waters, was a beauty not of earth that took away all fear, until he seemed to be gazing into the seventh heaven and seeing that which was unlawful for mortal man to look upon.

Only a moment, and once more he was back in the body and found himself looking confusedly into the faces of his companions, all of whom had felt something of the same uplift. Without a word, the Indian edged the canoe along the shore and into the mouth of a deep lagoon, half-hidden by overhanging trees. Beyond these it widened out and ended in a high, bare bank. Back from this stretched a narrow path, showing like a long line through the dark green of the jungle. Its surface was trodden ominously hard and smooth, as if crossed and recrossed by many bare feet.

"The Trail," said Pinto, softly.

"The Trail," echoed Professor Ditson, as they all stared along the thin line which pierced the forest and led away and across the vast basin of the Amazon and on and past the guarded heights of Peru until it reached the mines from which Spain had dug the gold which enabled her to conquer and hold half the world. Only the cruel, fierce, dogged fighters of Spain as she was four hundred years ago could have cut this path. Even then, when men thought little of life or of accomplishing the impossible, the Trail stood forth as a great achievement, every mile of which had cost the lives of men.

For a time, the adventurers stared in silence at the brown line athwart the green, the sign and seal of an empire long passed away. Then Pinto grounded the montaria at the edge of the bank, and, after all of the party had disembarked with their scanty equipment, pulled the boat, with Hen's help, back of a screen of tangled vines, marked by a slender assai-palm, until it was completely hidden from sight.

"If we are successful," remarked Professor Ditson, "we'll never see that boat again. If we are driven back along this trail, it may save our lives."

There was a silence. For the first time the boys and Jud realized that their leader definitely expected perils other than those ever present from the wild creatures that guarded the beautiful, treacherous, mysterious forests of this southern continent.

"Are the Injuns down here dangerous?" inquired Jud, at last.

"The personal habits of some of them do not commend themselves even to the most broad-minded investigators," returned the professor, precisely.

"Such as—" questioned Jud, again.

"Well," replied the scientist, slowly, "for one thing, the wild tribes of this part of the Amazon basin invariably eat any captives they make. Then—"

"That's enough," broke in Jud. "After I've been eaten I don't care what they do next. What might be the names of these gentlemen?"

"The Mayas, I think, are the tribe we shall be most likely to meet," said Professor Ditson, reflectively. "They have no fixed homes, but wander through the forest, guiding themselves by the sun, and sleep in the tree-tops like monkeys wherever they happen to be when night comes. They hunt men, red, white, or black," he went on; "yet, if Indian traditions can be depended upon, we do not need to be afraid of them so long as we keep to the Trail."

"How's that?" inquired Will, intensely interested.

"Every tribe which refers to the Trail," the scientist informed them, "speaks of a custom called the 'Truce of the Trail,' under which travelers along that road are safe from attack."

"Does that there truce," interposed Jud, "take in white men, or is it only for redskins?"

"That," returned the professor, "is not certain. Some say yes, some say no."

"The question is," murmured Jud, "what do the Mayas say?"

"If we pass the Trail in safety," went on Professor Ditson, "we still may expect trouble from Dawson after we get into the Peruvian highlands. He has great influence with a band of Indian outlaws who call themselves the Miranhas, or Killers, and may persuade them to ambush us in order to secure the map."

"I sure am lookin' forward to this pleasure-trip of ours," confided Jud to Will.

During the first day along the trail, Will, who was next to Pinto, tried to pass away the time by learning a few words of Mundurucu. His first lessons in that language, however, were somewhat discouraging, since the dialects of the South American Indians contain perhaps more syllables to a word than any other language on earth.

"Pinto," he began, "I'll point to things, and you tell me what they are in Indian, and keep on saying it over and over until I learn it."

"All right," agreed the Mundurucu.

"Professor Pinto," went on Will solemnly, pointing to his hand, "what's that?"

"In-tee-ti-pix-tee-e-toke-kee-kee-tay-gaw," clattered Pinto, in a breath.

"Hey, hold up there," said Will. "Try it in low."

Half an hour later found him still working on that single word.

"Whew!" he remarked when he finally had it memorized, "I've heard it takes eight years to learn Eskimo. It's liable to take me eighty before I can talk Mundurucu. What about this one?" he went on, undiscouraged, pointing to a curious tree with a mahogany-red bark—which, if he had but known it, was a stranger whose seeds had in some way drifted down from much farther north.

"E-lit-ta-pix-tee-e-fa-cho-to-kee-not-e," said Pinto, slowly and distinctly.

For fifteen minutes Will wrestled with this new word.

"Do you know what he said?" at last interrupted Professor Ditson, who had been listening to the lesson.

"He gave me the name for that tree, didn't he?" returned Will, a little peevishly.

"Not at all," said the scientist. "He simply said, 'I don't know.'"

"Not so blame simply, either," murmured Jud, who had also been following the lesson.

"Our own language is full of similar mistakes imported from native dialects," lectured Professor Ditson. "'Kangaroo' simply means 'I don't know' in Bushman; so do 'mosquito' and 'quinine' and 'cockatoo' in different Indian languages."

"Well," said Will, "I'm going to pass up Mundurucu. Here I've spent the better part of an hour in learning two words—and one of them isn't right."

"It's a gift, my boy," said Jud, patronizingly. "As for myself, I once learned three Indian languages, Apache, Comanche, an' Sioux, in less than a month."

"Indeed!" broke in Professor Ditson, cuttingly. "You surprise me. Won't you favor me with a few sentences in Apache?"

"Surely," returned Jud, generously. "Ask me anything you like in Apache, an' I'll be glad to answer it in the same language."

The appearance of a small pond ahead put a stop to further adventure in linguistics, since Pinto had promised to catch some fish from the next water they met. As they came to the shore, suddenly, before Jud's astonished eyes, a fish about a foot long thrust its head out of the dark water, opened its mouth, and breathed like any mammal. A moment later it meowed like a cat, growled like a dog, and then went under.

"I'll never dare tell 'em about this in Cornwall," exclaimed Jud, earnestly, as the talented fish disappeared. "They'd think I was exaggeratin', an' that's one thing I never do. This trip," he went on reflectively, "is liable to make me believe blame near anything."

It was Professor Ditson who told them that the strange fish was a lung-fish and was a link between the fishes and the reptiles.

A little later, Pinto, with a length of flexible palm-fiber, noosed a garpike, that strange representative of the oldest family of fishes left on earth, and another link with the reptiles. Its vertebrÆ had ball-and-socket joints like the spine of a snake, and, unlike any other fish, it could move its head independently of its body. Armored scales arranged in diagonal rows ran down its back, being fastened to each other by a system of hooks, instead of lapping over each other like the scales of other fishes. This armor was of such flinty hardness that Pinto struck a spark from it with his steel, and actually lighted from its own scales the fire on which the fish was cooked.

By this pond grew a great orchid with thirty-one flower-stems, on one of which Will counted over a thousand beautiful pearl-and-gold blossoms. Near the water, too, were many varieties of tropical birds flaming through the trees. Among them were flocks of paraquets colored green and blue and red; little honey-creepers with black, purple, and turquoise plumage and brilliant scarlet feet; and exquisite tiny tanagers like clusters of jewels with their lilac throats, turquoise breasts, topaz crowns, and purple-black backs shading into ruby red. These were all searching for insects, while among the blossoms whirred dainty little humming-birds of the variety known as "wood-stars." Then there were blood-red macaws with blue-and-gold wings, and lustrous green-black toucans with white throats, red-and-yellow tail-coverts, and huge black-and-yellow bills.

For the next few days the treasure-hunters followed the narrow, hard-beaten path through stretches of dark jungle and thorny thickets, or found themselves skirting lonely lakes hidden in the very heart of the virgin forest. Everywhere the Trail was omniously clear and hard-trodden. Sometimes they all had that strange knowledge that they were being watched, which human beings who live in the open acquire as well as the wild folk.

At last there came a day when the supplies had run so low that it became necessary for Pinto to do some hunting. Will went with him, and together they silently and cautiously followed one of the many little paths that at irregular intervals branched off from the main trail. This one was so hidden by vines and creepers that it seemed improbable that any one had used it for a long period of time. It led the hunters into one of the patches of open country sometimes found in the forests of the Amazon. This particular one was fringed with great trees and crossed by another path nearly parallel to the one they were following.

Near the center of the clearing, Pinto managed to shoot two curassows, huge, plump birds which looked and tasted much like turkeys. Leaving these with his companion, the Indian pushed on ahead for more. Suddenly he reappeared among the trees, and Will noticed as he hurried toward him, that his copper-colored face showed gray and drawn, while beads of sweat stood out on his forehead. As he joined the boy, Pinto placed his finger on his lips with a look of ghastly terror and led Will into the deepest part of a near-by thicket. From there, though hidden from sight, they had a view through the close-set bushes of the other path. Suddenly, from far down that trail, sounded a faint, but regular, clicking noise. As it became louder and louder, rising and falling in a regular cadence, Pinto slipped like a snake deeper into the long jungle-grass.

"Lie still for your life," he whispered in Will's ear, so faintly that the boy could scarcely make out the words. Then, in an instant, from out of the jungle not twenty feet away there strode along the dim path a figure of nightmare horror—that of a tall naked man, with gaunt and fleshless arms and legs, great knobs of bone marking his knee and elbow-joints. His sunken body was painted black, with every bone outlined in a chalky white, so that he seemed a living, walking skeleton.

Around the black and wasted neck, wrinkled like that of a mummy, hung a long string of small bones which, with a thrill of horror, the boy recognized by their nails as those of human fingers. It was these, striking together, which made the clicking noise that Will had heard. The face of the horror was painted black, except the lips and chin, which showed blood-red, while out of the holes at the corners of the lower lip protruded curved, gleaming peccary-tusks. These ornaments gave an indescribably brutish appearance to the countenance that they ornamented, while above them two snaky black eyes with an expression of implacable cruelty glittered like crumbs of glass from under overhanging brows. Like a specter, the shape disappeared among the shadows; but it was followed by another and another and another, until a long procession of terrible figures had passed.

As the ill-omened clicking died away in the distance Will sprang to his feet.

"No!" hissed the Indian. "Our only chance of life is to lie quiet. That is a Maya war-party on a man-hunt!"

"They'll meet the others on the Trail," whispered Will.

"Six men can't do any more against fifty than two," returned Pinto, practically. "We'll only throw away our lives and not save theirs."

"Stay if you want," returned the boy; "I'll live or die with them!" and he sped back at full speed along the path over which they had come. Just before he reached the Trail he looked back—and there was Pinto at his shoulder.

"Very foolish," the latter muttered, "but—I come too."

Down the Trail the two hurried, and, rounding a bend, burst in suddenly upon the rest of the party lying in the shade of the overhanging trees awaiting their return.

"Mayas! Mayas!" gasped Pinto.

As he spoke, far down the Trail from around a curve sounded the faint, ominous clicking which the two hunters had heard before.

It was then that the old scientist showed that he deserved the right to lead which he claimed.

"Stand still!" he said sternly to Pinto, as the latter seemed inclined to bolt down the Trail away from the fatal sound. "Put up your gun!" he ordered Jud; "the Truce is our only chance."

Then, with quick, decisive commands, he lined the party up so that no part of the body of any one of them extended beyond the surface of the Trail, and yet a space was left wide enough to allow any others using the path to pass. At the head of the line he placed the two Indians, Joe and Pinto, so that the Mayas might note the presence in the party of members of their own race.

"Show the peace sign," he snapped sharply to Joe, who led the line. "Brace up!" he went on, slapping Pinto sharply on his bare back; "don't look so scared. No matter what they do," he said, turning to the rest of the company, "don't leave the Trail for a second or make any kind of attack on them. They will probably try to make us break the Truce of the Trail. If any of us do, we are all lost."

"My peace sign," muttered Jud, grimly, "will be an automatic in one hand an' this little toothpick in the other," and he opened the five-inch blade of the jack-knife with which he had killed old Three Toes, the grizzly, as already chronicled in "The Blue Pearl." "If I'm goin' to be eaten," he went on, "there'll be eighteen Mayas that ain't goin' to have any appetite for the meal"; and he shifted the single clip of cartridges remaining, so that he could feed them into the automatic if it came to a last stand.

All further conversation was ended by the appearance of the same horrible apparition which had so terrified Pinto a short time before. As the gaunt painted skeleton of the first Maya showed against the green background, surmounted by the black and blood-red face with the grinning tusks and implacable eyes, an involuntary gasp went up from the whole waiting party. Jud slipped the safety-catch from his revolver; Pinto's face looked as if suddenly powdered with ashes; Will's hands stole to the hatchet at his belt; while, down at the end of the line, Hen Pine gripped his heavy machete until his great muscles stood out like iron bands. Two of the party alone showed no sign of any emotion: Joe, the descendant of a long line of proud Chippewa chiefs, disdainfully stretched out both empty hands palms up in the peace-sign; while Professor Ditson's calm face seemed to show only the mild interest of a scientist.

As the leading Maya caught sight of the waiting line, he slowed his swift stride and the war-party crept up close and closer. Then came the tense moment which would decide whether the Truce was to hold. As the grim hunters moved up, there was no sign on the face of any of them of any acceptance of the peace which Joe had offered. With short, gliding steps, they made a complete circle around the little party, closing up until their menacing, fearful faces were less than a foot away and the reek of their naked bodies was like the hot taint of jaguars of the jungle in the nostrils of the waiting six. In their left hands they carried bows and quivers of fiercely fanged arrows gummed with fatal venom, while from their belts swung curved, saw-toothed knives and short, heavy clubs, the heads of which were studded with alligators' teeth.

As the Mayas came closer, the waiting line wavered involuntarily before the terrible menace of their hating, hateful faces. The Mundurucu especially, although no coward, had been taught from earliest childhood to dread these man-eaters, the Mayas. It was Professor Ditson who noticed that, in spite of their menacing approach, not a single warrior had as yet gripped a weapon.

"Steady, Pinto, steady all," he said calmly, "They're trying to stampede us. If one of you leaves the Trail, we're all dead men."

He spoke just in time, for already Pinto was looking longingly toward the refuge of the forest, forgetting that the woodcraft of those hunters of men was superior even to his own. Perhaps even Professor Ditson's voice would not have stopped him if it had not been for a sudden happening.

As the leader of the Mayas half-circled around Joe, the latter turned to face him, still holding out his arms. The motion flung open his flannel shirt, unbuttoned to the waist, and showed, tattooed red on his brown skin, the curling, twisted totem-mark of intertwined serpents by which Joe had claimed the right of his blood in the lodge of the Great Chief during the quest of the Blue Pearl. As the Maya caught sight of this sign he stopped in his tracks. Little by little the menace died out of his fierce eyes, and, as if drawn by a magnet, he crept in closer and closer with outstretched neck, staring at the tattoo marks which wound down and around Joe's waist. Then, with a sudden gesture, he swept aside the ghastly necklace that he wore. There, outlined against his fleshless chest just over his heart, showed a similar emblem—crimson inter-twining serpents facing in opposite directions, with gaping mouths like those of which the totem-pole was made which towered before the lodge of the Great Chief in far-away Akotan. The Maya chief stood motionless for a moment. Then he stretched both hands out toward Joe, palms up, and stood as if waiting.

"Put your hands in his, boy," hissed Jud, from down the line; "he's waitin' for the brotherhood sign."

Without a word, Joe clasped hands with the Maya chief, and for an instant the two looked into each other's eyes, the spectral cannibal and the lithe son of a French trapper and a Chippewa princess. Then, disengaging his right hand, the Maya fumbled at his belt and suddenly stretched out toward Joe the supple, beautiful tanned skin of a snake, such as but one of the party had ever seen before. It was long and narrow and of a flashing golden-yellow, thickly flecked with tiny red-brown spots. This he wound around the boy's neck, so that it swung gleaming against his gray flannel shirt. Once again with outstretched hands the strange figure stood as if waiting, encircled the while by fierce, impassive faces with tusks gleaming horribly against blood-red jaws, and white painted bodies showing like ghosts against the green of the forest.

"Give him your tie," dictated Jud. "Don't you know blood-brothers have to exchange presents?"

Joe hesitated. He had a weakness, perhaps inherited from both sides of his family, for neckties of the most barbaric colors. The one that he was wearing was one of Cornwall's best and brightest, a brilliant green-and-purple creation which had cost him a whole dollar at White Wilcox's store. To give it up would leave him tieless in a great wilderness.

"Hurry!" muttered Professor Ditson, as the Maya chief began to lower his outstretched hands.

Thus urged, the boy reluctantly pulled a foot of glimmering silk from his neck, and the next instant the most brilliant tie that ever graced Mr. Wilcox's emporium was gleaming against the gray-white of a necklace of human bones.

The Maya received the enforced present with a grunt of undisguised pleasure, and, raising both hands above his head with palms outstretched, faced his waiting band and began a crooning song filled with strange minor cadences. One by one his men took up the strain, and, led by him, filed away from the trail like ghosts going back to their graves. As the clicking of their necklaces and the notes of their chant sounded faint and fainter and at last died away in the green tangle of the jungle, a long sigh of relief came unconsciously from every member of the expedition. It was Jud who first broke the silence.

"I've always heard," he said, "that Injuns north, south, east, an' west belonged to the four main totems, the Bear, the Wolf, the Snake, an' the Eagle, but I never believed it before to-day. That old tattoo-mark, boy," he went on, turning to Joe, "certainly came in right handy."

"He gone off with my good tie," returned Joe, sorrowfully.

"And a good job, too, I call it," remarked Will, who had never approved his friend's taste in neckwear.

It was the Maya's present which most interested Pinto and Professor Ditson. The Mundurucu Indian sidled up close to Joe and stared at the glittering skin with all his eyes, but without attempting to touch it.

"It's the sacred snake that in the old days only kings and gods could wear," he murmured.

"He's right," said Professor Ditson, raising the gleaming, golden skin reverently from Joe's neck. "It's the skin of the Yellow Snake which the Aztecs used to wind around the forehead of Atapetl, their terrible goddess of war. Only her priests knew where to find these snakes, and it was death for any one else even to look at the skin except at the annual sacrifices of the goddess. This one," he went on, "will be a safe-conduct for the whole party all the way to Peru—and ought to be a lesson to you," he continued severely, turning to Jud, "never to speak against snakes again."