"You mean we may be able to fly down into the crater?" Monk asked.

"We’re going to try just that," Doc smiled.

UP and up climbed the powerful speed-plane, motors moaning an increasing song of effort. The first wisps of steam whipped grizzled pennants about the craft. Doc opened the cockpit windows and kept an accurate check on a thermometer.

"This is nothing but cloud formation caused by very warm and moist air lifting out of the crater!" he called, raising his voice over the motor howl — for opening the windows nullified the soundproofing of the cabin.

The vapor thickened. It poured densely into the cabin. The very world about them seemed to turn a bilious gray hue. Visibility was wiped out, except for a few score yards, beyond the wing tips.

"Long Tom," Doc’s energetic voice had little trouble piercing the engine clamor, "set the danger alarm for five hundred feet!"

Long Tom hastily complied. This danger alarm was simply an apparatus which sent out a series of bell-like sounds very distinctive from the motor uproar, and another sensitive device which measured the time that ensued until an echo was tossed back by the earth. If this time interval became too short, an alarm bell rang.

With it in operation, if the plane came blindly within five hundred feet of the crater bottom or sides, an alarm would sound. Doc had perfected this device. It was little different from the apparatus all modern liners use to take depth measurements.

Deeper into the crater moaned the plane. It spiraled tightly, as though descending the thread of an invisible screw in the crater center. It might have been a tiny fish in a sea of milk.

"Let’s go back!" wailed Oliver Wording Bittman. "This is a horrible place!"

"It does kinda give a guy the creeps!" Monk muttered.

" Ye-e-ow-w! Look at that thing!"

Monk’s squawl of surprise was so loud it threatened to tear the thin metal sides off the plane. Every eye focused in the direction both his great, hairy arms pointed. What they saw was little, but it chilled the blood in their veins.

A black, evil mass seemed to bulk for an instant in the gray domain of vapor. It might have been a tortured, sooty cloud from the way it convulsed and changed its shape. Then it was gone, sucking after it a distinct wake of the pigeon-colored vapor.

"I c-couldn’t h-have s-seen what I d-did!" Monk stuttered.

"What was it?" Ham shouted. "What was that thing in the cloud? It looked big as this plane!"

Monk panted like a runner. His eyes still protruded.

"It wasn’t quite that b-big!" he gulped. "But it was the ugliest thing I ever saw! And I’ve seen plenty of ugly things!"

"If you own a mirror, you have!" Ham couldn’t resist putting in.

Monk made no reference to pigs — which was in itself demonstration of what a shock he had just received.

"I saw one of them flyin’ devils the natives on the atoll told Doc about!" Monk declared. "And what I mean, flyin’ devil is the name for it."

"You must have had a swig of that caterpillar liquor," Ham jeered.

"Quick!" Doc Savage’s mighty voice crashed through the plane. "The machine guns! Off to the right! Get that thing! Get it! Shoot it!"

Every one gazed to the right.

"It’s comin’ back — the flyin’ devil!" Monk bawled.

The black, evil mass had appeared in the misty world again. It convulsed and altered its shape, as before. But now the aviators had the opportunity to see what it really was — they could drink in the awful horror of the monster with their eyes.

THE thing was flying along — keeping pace with the plane! Terrible eyes appraised the ship, as though deciding whether to attack.

It had a ghastly set of jaws — nearly as long as a man’s body, and spiked full of foul, conical teeth. The body had neither hair nor feathers — it was like the skin of a dog denuded by the mange.

Most awesome of all were the wings, for they were membranous, like those of a bat. As they folded and unfolded in flight, the membrane fluttered and flapped like unclean gray canvas. On the tip of the first joint of the wings were four highly developed fingers, armed with fearful talons.

The appalling monster suddenly gave vent to its cry. This was an outrageous combination of a roaring and gargling, a sound of such volume that it reduced the pant of the plane motors to insignificance. And the noise had an ending as ghastly as its note — it stopped in a manner that gave one the sickening impression that the noise itself had choked to death the gruesome thing.

"A prehistoric pterodactyl!" screamed Johnny. "That’s what it is!"

"A what?" grunted Monk.

"A pterodactyl, a flying reptile of the Pterosauri order. They were supposed to have become extinct near the end of the Mesozoic age."

"They didn’t!" snorted Monk. "You can look for yourself!"

"Use those machine guns!" Doc directed. "The thing is going to attack us!"

The hideous flying reptile was slowly opening its huge, tooth-armed jaws!

Rapid-firer barrels poked through the plane windows. They spewed. Empty cartridges rained on the floorboards. Bullets found their mark.

The aлrial reptile started its blood-curdling cry. The sound ended in a drawn, piercing blare. The thing fell, bones broken, foul canvas like wings flapping. It was like a dirty gray cloth somebody had dropped.

Monk grinned. "What a relief that it — "

The plane lurched madly as Doc whipped the controls about.

A second of the prehistoric pterodactyls had materialized out of the vapor. A gigantic, eerie thing reminiscent of a mangy crocodile clad in a great gray cape, it plunged at the plane.

Its horrid, conical teeth closed upon the left wing. A wrench, a gritty scream of rending metal — and the plane wing was ruined! The ship keeled off on a wing tip and began a slow spin.

The pterodactyl hung to the wing it had grabbed, like a tenacious bulldog.

"The parachutes!" Doc barked. "Jump! We may crash any instant!"

Chapter 16. THE AWFUL NIGHT

IN quick succession, Doc’s five men piled through the plane door, hands on the ripcord rings of their backpack parachutes.

Renny was first to go. Monk paused to grab his can of tobacco out of a seat, then followed. Long Tom, Ham and Johnny dived after him.

Only Oliver Wording Bittman held back, trembling.

"I don’t want — " he whined.

"Neither do we!" Doc said firmly. "There’s no choice!" Then, before it should be too late, Doc swept Bittman up in bronze arms of vast power and sprang with him into space.

As calmly as though he were on solid ground, Doc snapped open Bittman’s ‘chute, then dropped down a few hundred feet and bloomed his own mushroom of silk. A jerk, and he floated gently. He had time to view the astounding domain about him.

The vapor, as he had half suspected would be the case, was becoming less dense. At the same time, the warmth increased. The hot, moist air, suddenly striking the cool strata above the crater, formed the steamlike clouds, which had curtained whatever additional shocking secrets the place held.

A stutter of machine-gun shots below drew Doc’s golden eyes. He hastily plucked his own compact rapid-firer from its belt holster.

The pterodactyl had released its silly hold on the falling plane and had attacked Johnny. The lanky archaeologist’s bullets had driven its first dive aside. But it was coming back. The repellent jaws were widely distended. Each of the many odious, conical teeth could pierce through a man’s body.

Doc’s machine gun clattered. He knew where to aim. Greater even than the learning of Johnny, whose profession was knowing the world and all its past, was Doc Savage’s fund of knowledge on prehistoric reptiles and vegetation. Doc realized this pterodactyl probably had little or no brain. He shot for the neck bones and shattered them.