The treacherous ground crumbled beneath the scientist’s feet, and, amid an avalanche of loose stones and débris, he pitched headlong into the glade.

But for a fortunate chance he would assuredly have broken his neck in the fall. Instead of striking the solid ground below, Mervyn landed with a thud upon the back of the sleeping monster.

The shock awoke the creature, and, with a hoarse snort of rage, it rose to its feet, shaking itself furiously to dislodge its unnatural burden.

Terrible enough it had looked as it lay asleep, but now, in its rage, its appearance was enough to daunt the boldest.

Small wonder that Mervyn was half mad with terror, as, clutching desperately at the monster’s bony necklet, he strove to prevent the brute unseating him, and pounding him to a jelly beneath its terrible hoofs, which, even now, were trampling the floor of the glade in a paroxysm of fury.

At length, finding himself utterly unable to get rid of the encumbrance, the monster broke out of the glade at a lumbering trot, and thundered across the plain which lay beyond.

As for Garth and Seymour, they stood for a few seconds as though stunned. The thing had happened so suddenly that it had paralysed their powers of action, dried up the fountain of their energies.

When at last they recovered their scattered wits, the two scrambled recklessly down the side of the ridge and hurried out on to the plain.

But the thunderous tread of the Triceratops had already died away, and there was no sign of their friend.

“We must follow the trail,” Seymour muttered, pointing to the broadly-defined track made by the monster’s hoofs, which stretched away into the darkness.