ALL five of the men who composed the male populace of Third House gathered in Haynes' room at ten o'clock that night. Everard Colton and old Johnston had been told briefly of the killing of Serdholm.

“Thus far,” said Haynes, addressing the meeting, “this vigilance committee has been a dismal failure. Had anyone told me that five intelligent men could fail in finding the murderer, with all the evidence at hand, I should have laughed at him.”

“Some features which might be regarded as unusual have presented themselves,” suggested Professor Ravenden mildly.

“Unusual? They're absurd, insane, impossible! But there are the dead bodies, man and brute. We've got to explain them, or no one knows who may come next.”

“We've got to be careful, certainly,” said Colton; “but I think if we can capture Whalley, we'll have no more mysterious killings.”

“Oh, that does very well in part; but it doesn't fill out the requirements,” said the reporter impatiently. “Now, I'm going to run over my notes briefly, and if anyone can add anything, speak up. First, the killing of the seaman, Petersen, on the night of the shipwreck. That was on the thirteenth, an uncanny date, sure enough. Next, the killing of the sheep by the same wound, on the fourteenth, and on the same evening Professor Ravenden's experience with some threatening object overhead.”

“Pardon me; I did not ascribe any threatening motive or purpose to the manifestation,” put in the professor. “Indeed, if I may challenge your memory, I suggested an air-ship. It seems that the unhappy aero-expert's kites well may have been the source of the sound I heard.”

“Let us assume so for the present. Next we come to Mr. Colton's encounter and the death of the mare on the evening of the fifteenth.”

“The kites again, of course,” said Everard. “Even allowing that—and I expect to get conclusive proof against it later—what, then, chased the animal over the cliff?”

“Maybe the kites came down later and blew along the ground after her. If you were a horse, and a string of six-foot kites came bounding along in the darkness after you, wouldn't you jump a cliff?”

“Ask Professor Ravenden,” suggested Haynes maliciously.

“The jest is not an unfair one,” said the scientist good-humouredly. “I fear that I should.”

“Charge the death of the mare to the kites, then. Pity we can't lay the sheep to their account too. The third count against them is Professor Ravenden's adventure of the eighteenth, and the death of the aeronaut. As to Professor Ravenden's part, there remains to be explained the cutting of the kite strings, if they were cut.”

“That must have been done, it would seem, in mid-air, just as Petersen the sailor was killed,” said Dick Colton.

Haynes looked at him quickly. “Colton, you're beginning to show signs of reasoning powers,” he said. “I think I'd better appoint you my legatee for the work, if my turn should come next.”

“My dear Haynes,” Professor Ravenden protested, “under the circumstances that remark at least is somewhat discomforting.”

“You're quite right, Professor. Down with presentiments! Well, as Dr. Colton suggests, there's a rather interesting parallel between the mid-air killing of the sailor and the mid-air cutting of the kite cord. Let that go, for the present. Mr. Ely's death we can hardly ascribe to his own kites. There's the cutting of the string near his hand.”

“That blasted Portuguese murderer, Whalley,” said Johnston.

“Most probably. The wound is such as his big knife would make; we know he's abroad on the knolls. But why should he kill Mr. Ely, whom he never saw before, and why in the name of all that's dark should he cut the kite strings?”

“Murderous mania; the same motive that drove him to kill the sheep,” said Dick Colton. “As for the kite string, perhaps he got tangled in it.”

“There is no tangle,” replied the reporter, “except in the evidence. But we'll call that Whalley's work. We come to to-day's murder now. Who did that?”

“Without assuming any certainty in the matter, I should assume the suspicion to rest upon the juggler,” said Professor Ravenden.

“Motive is there,” said Dick Colton. “What Serdholm told us about his thumping Whalley shows that.”

“Yes; but there is motive in the case of Bruce also. And we know that Bruce was there. Moreover, he was on the cliff-head when Petersen came in, and the two wounds are the same.”

“Surely,” began the young doctor, “you don't believe that Bruce-”

“No, I don't believe it,” interrupted the reporter; “but it's a hypothesis we've got to consider. Suppose Bruce and Serdholm recognised this man Petersen as an enemy, and Bruce slipped a knife into him as he took him from the buoy?”

“But I thought Petersen was killed halfway to the shore.”

“So we suppose; but it is partly on the testimony of these two that we believe it, corroborated by circumstantial evidence. Now, if Bruce killed the sailor, Serdholm knew it. The two guards quarrelled and fought. Bruce had reason to fear Serdholm. There's the motive for the murder of Serdholm. He met him alone—there is opportunity. I think the case against him is stronger than that against Whalley, in this instance. I've looked into his movements on the night of the sheep-killing and the murder of Mr. Ely. He was out on the former, and in on the latter.”

“That weakens the case,” said Everard Colton. “Yes; but what ruins the case against both Bruce and Whalley in the killing of Serdholm is this.” Haynes spread out on his table a map which he had drawn. “There is the situation, sketched on the spot. You will see that there are no footprints other than our own leading to or going down from the body. Gentlemen, as sure as my name is Haynes, the thing that killed Paul Serdholm never walked on human feet!”

There was a dead silence in the room. Dick Colton's eyes, narrowed to a mere slit, were fixed on the reporter's face. Johnston's jaw dropped and hung. Everard Colton gave a little nervous laugh. Professor Ravenden bent over the map and studied it with calm interest.

“No,” continued Haynes, “I'm perfectly sane. There are the facts. I'd like to see anyone make anything else out of it.”

“There is only one other solution,” said Professor Ravenden presently: “the fallibility of the human senses. May I venture to suggest again that there may be evidences present which you, in your natural perturbation, failed to note?”

“No,” said the reporter positively. “I know my business. I missed nothing. Here's one thing I didn't fail to note. Johnston, you know this neck of land?”

“Lived here for fifty-seven years,” said the innkeeper.

“Ever hear of an ostrich farm hereabouts?”

“No. Couldn't keep ostriches here. Freeze the tail-faithers off'em before Thanksgiving.”

“Professor Ravenden, would it be possible for a wandering ostrich or other huge bird, escaped from some zoo, to have its home on Montauk?”

“Scientifically quite possible in the summer months. In winter, as Mr. Johnston suggests, the climate would be too rigorous, though I doubt whether it would have the precise effect specified by him. May I inquire the purpose of this? Can it be that the tracks referred to by the patrol were the cloven hoof-prints of-”

“Cloven hoofs?” Haynes cried in sharp disappointment. “Is there no member of the ostrich family that has claws?”

“None now extant. In the processes of evolution the claws of the ostrich, like its wings, have gradually——”

“Is there any huge-clawed bird large enough and powerful enough to kill a man with a blow of its beak?”

“No, sir,” said the professor. “I know of no bird which would venture to attack man except the ostrich, emu or cassowary, and the fighting weapon of this family is the hoof, not the beak.”

“Professor,” interrupted Haynes, “the only thing that approached Serdholm within striking distance walked on a foot armed with five great claws. You can see the trail on this map.” He produced a large sheet of paper on which was a crude but careful drawing. “And there is its sign-manual, life-size,” he added, pushing a second sheet across the table to the scientist.

Imagination could hardly picture a more precise, unemotional and conventially scientific man than Professor Ravenden. Yet, at sight of the paper his eyes sparkled, he half started from his chair, a flush rose in his cheeks, he looked keenly from the sketch to the artist, and spoke in a voice that rang with a deep under-thrill of excitement:

“Are you sure, Mr. Haynes—are you quite sure that this is substantially correct?”

“Minor details may be inexact. In all essentials that will correspond to the marks made by something that walked from the mouth of the gully to the spot where we found the body and back again.” Before he had fairly finished the professor was out of the room. He returned almost immediately with a flat slab of considerable weight. This he laid on the table, and taking the drawing, sedulously compared it with an impression, deep-sunken into the slab. For Haynes a single glance was enough. That impression, stamped as it was on his brain, he would have identified as far as the eye could see it.

“That's it!” he cried with the eagerness of triumphant discovery. “The bird from whose foot that cast was made is the thing that killed Serdholm.”

“Mr. Haynes,” said the entomologist dryly, “this is not a cast.”

“Not a cast?” said the reporter in bewilderment. “What is it, then?”

“It is a rock of the cretaceous period.”

“A rock?” he repeated dully. “Of what period?”

“The cretaceous. The creature whose footprint you see there trod that rock when it was soft ooze. That may have been one hundred million years ago. It was at least ten million.”

Haynes looked again at the rock, and superfluous emotions stirred among the roots of his hair. “Where did you find it?” he asked presently.

“It formed a part of Mr. Johnston's stone fence. Probably he picked it up in his pasture yonder. The maker of the mark inhabited the island where we now are—this land then was distinct from Long Island—in the incalculably ancient ages.”

“What did this bird thing call itself?” Haynes demanded. A sense of the ghastly ridiculousness of the affair was jostling, in the core of his brain, a strong shudder of mental nausea born of the void into which he was gazing.

“It was not a bird. It was a reptile. Science knows it as the pteranodon.”

“Could it kill a man with its beak?”

“The first man came millions of years later—or so science thinks,” said the professor. “However, primeval man, unarmed, would have fallen a helpless victim to so formidable a brute as this. The pteranodon was a creature of prey,” he continued, with an attempt at pedantry which was obviously a ruse to conquer his own excitement. “From what we can reconstruct, a reptile stands forth spreading more than twenty feet of bat-like wings, and bearing a four-foot beak as terrible as a bayonet. This monster was the undisputed lord of the air; as dreadful as his cousins of the earth, the dinosaurs, whose very name carries the significance of terror.”

“And you mean to tell us that this billion-years-dead flying swordfish has flitted out of the darkness of eternity to kill a miserable coast-guard within a hundred miles of New York, in the year 1902?” broke in Everard Colton.

“I have not said so,” replied the entomologist quickly. “But if your diagram is correct, Mr. Haynes, if it is reasonably accurate, I can tell you that no living bird ever made the prints which it reproduces, that science knows no five-toed bird, and no bird whatsoever of sufficiently formidable beak to kill a man; furthermore, that the one creature known to science which could make that print, and could slay a man or a creature far more powerful than man, is the tiger of the air, the pteranodon.”

“Evidence wanted from the doctor!” cried Haynes. “Colton, can you add anything to this theory that Serdholm was killed by a bayonet-beaked ghoul that lived ten or a hundred or a thousand million years ago?”

“I'll tell you one thing,” said the doctor: “The wound isn't unlike what a heavy, sharp beak would make.”

“And that would explain the sailor being killed while he was coming in on the buoy!” exclaimed Everard Colton. “But—but this pteranodon—is that it? Oh, the deuce! I thought all those pteranothings were dead and buried long before Adam's great-grandfather was a protoplasm.”

“My own belief is that Mr. Haynes' diagram is faulty,” said Professor Ravenden, to whom he had turned.

“Will you come and see?” challenged Haynes.

“Willingly. Would it not be well to take the rock along for comparison?”

“Then we'd better all go,” said Everard Colton, “and carry the rock in shifts. It doesn't look as if it had lost any weight with age.”

As the party reached the large living-room, Helga Johnston sprang up from the long cushioned rest near the fireplace. Her face was flushed with sleep. In the glow of the firelight an expression of affright lent her beauty an uncanny aspect. Her breath came in little gasps, and her hands groped and trembled.

“What is it, Miss Helga?” cried Everard, running eagerly forward.

Unconsciously her fingers closed on his outstretched hand, and clung there.

“A dream!” she said breathlessly. “A horrid dream!” Then turning to Haynes: “Petit PÈre, you aren't going out to-night?” she said, glancing at the lanterns which her foster-father had brought.

“Yes, Princess, we're all going.”

“Into danger?” asked the girl. She had freed herself from Colton's grasp, but now her eyes fell on his again.

“No; just to clear up a little point. We shall all hang together.”

“Don't go to-night, Petit PÈre!” There was an imploring intonation in the girl's flute-like voice.

Haynes crossed over to her rapidly. “Princess, you're tired out and nervous. Go to bed, won't you?”

“Yes; but promise me—father, you too, all of you—promise me you won't any of you let yourselves be alone.”

“My dear child,” said Professor Ravenden, “I'll give you my word for the party, as I am the occasion of the expedition.”

“I—I suppose I am foolish,” Helga said; “but I have dreamed so persistently of some terrible danger overhanging—floating down like a pall.” With a sudden gesture she caught Haynes' hand to her cheek. “It hung over you, Petit PÈre!” she whispered.

“I'll throw a pebble at your window to let you know I'm back alive and well,” he said gaily. “I've never seen you so nervous before, Princess.”

“You'll hardly need the lantern,” said the girl, walking to the door, and looking up at the splendid moon, sailing in the unflecked sea of the Heavens.

“When you're looking for foot-prints on the sands of time,” observed Everard, “you need the light that never was on sea or land.”

He dropped back as the exploring party filed out into the night, and fell into step with Professor Ravenden.

“Isn't it true,” he asked, “that all these flying monsters are extinct?”

“Science has assumed that they were extinct,” said the Professor. “But a scientific assumption is a mere makeshift, useful only until it is overthrown by new facts. We have prehistoric survivals. The gar of our rivers is unchanged from its ancestors of fifteen million years ago. The creature of the water has endured; why not the creature of the air?”

“But,” said Colton combatively, “where could it live and not have been discovered?”

“Perhaps at the North or South Pole,” said the professor. “Perhaps in the depths of unexplored islands; or possibly inside the globe. Geographers are accustomed to say loosely that the earth is an open book. Setting aside the exceptions which I have noted, there still remains the interior, as unknown and mysterious as the planets. In its possible vast caverns there well may be reproduced the conditions in which the pteranodon and its terrific contemporaries found their suitable environment on the earth's surface, ages ago.”

“Then how would it get out?”

“The recent violent volcanic disturbances might have opened an exit.”

“Oh, that's too much!” Haynes broke in. “I was at Martinique myself, and if you expect me to believe that anything came out of that welter of flame and boiling rocks alive-”

“You misinterpret me again,” said the professor blandly. “What I intended to convey was that these eruptions were indicative of great seismic changes, in the course of which vast openings might well have occurred in far parts of the earth. However, I am merely defending the pteranodon's survival as an interesting possibility. As I stated before, Mr. Haynes, I believe the gist of the matter to lie in some error of your diagram.”

“We'll see in a moment,” said Haynes; “for here's the place. Let it down easy, Johnston. Wait, Professor, here's the light. Now I'll convince you.”

Holding the lantern with one hand, he uncovered one of the tracks with the other. The mark was perfectly preserved. “Good God!” said the professor under his breath.

He dropped on his hands and knees beside the print, and as he compared the to-day's mark on the sand with the rock print of millions of years ago, his breath came hard. Indeed, none of the party breathed as regularly as usual. When the scientist lifted his head, his face was twitching nervously.

“I have to ask your pardon, Mr. Haynes,” he said. “Your drawing was faithful.”

“But what in Heaven's name does it mean?” cried Dick Colton.

“It means that we are on the verge of the most important discovery of modern times,” said the professor. “Savants have hitherto scouted the suggestions to be deduced from the persistent legend of the roc and from certain almost universal North American Indian lore, notwithstanding that the theory of some monstrous, winged creature widely different from any recognised existing forms is supported by more convincing proofs. In the north of England, in 1844, reputable witnesses found the tracks, after a night's fall of snow, of a creature with a pendent tail, which made flights over houses and other obstructions, leaving a trail much like this before us. There are other corroborative instances of a similar nature. In view of the present evidence, I would say that this unquestionably was a pteranodon, or a descendant little altered, and a gigantic specimen, for these tracks are distinctly larger than the fossil marks. Gentlemen, I congratulate you both on your part in so epoch-making a discovery.”

“Do you expect a sane man to believe this thing?” Haynes demanded.

“That's what I feel,” said Everard Colton. “But, on your own showing of the evidence, what else is there to believe?”

“But, see here,” Haynes expostulated, all the time feeling as if he were arguing in and against a dream. “If this is a flying creature, how explain the footprints leading up to Serdholm's body, as well as away from it?”

“Owing to its structure,” said the professor, “the pteranodon could not rise rapidly from the ground in flight. It either sought an acclivity from which to launch itself, or ran swiftly along the ground, gathering impetus for a leap into the air with outspread wings. Similarly, in alighting, it probably ran along on its hind feet before dropping to its small fore feet. Now, conceive the pteranodon to be on the cliff's edge, about to start upon its evening flight. Below it appears a man. Its ferocious nature is aroused at the sight of this unknown being. Down it swoops, skims swiftly with pattering feet toward him, impales him on its dreadful beak, then returns to climb the cliff and again launch itself for flight.”

All this time Haynes had been holding one of the smaller rocks in his hand. Now he flung it toward the gully and turned away, saying vehemently: “If the shore was covered with footprints, I wouldn't believe it! It's too—”

He never finished that sentence. From out of the darkness there came a hoarse cry. Heavy wings beat the air with swift strokes. In that instant panic fell upon them. Haynes ran for the shelter of the cliff, and after him came the Coltons. Johnston dropped on hands and knees and scurried like a crab for cover. Only the professor stood his ground; but it was with a tremulous voice that he called to his companions:

“That was a common marsh or short-eared owl that rose. The Asio accipitrinus is not rare hereabouts, nor is it dangerous to mankind. There is nothing further to do to-night, and I believe that we are in some peril remaining here, as the pteranodon appears to be nocturnal.”

The others returned to him ashamed. But all the way home they walked under an obsession of terror hovering in the blackness above.

It was a night of restless and troubled sleep at Third House. For when the incredible takes the form of undeniable reason, and demands credence, the brain of man gropes fitfully along dim avenues of conjecture. Helga's premonition of impending disaster lay heavy upon the household.