At that instant, whilst they still hesitated, and the American was hoping that they would retire, Garth--aroused from his swoon by the din--sat up. One glimpse he caught of the nightmare-like forms clustered beyond the doorway, then a terrified cry burst from his lips. “Great Heavens! What devils!” He leapt to his feet, and at that, as though aroused to fresh fury by his movement, the river-creatures burst _en masse_ through the doorway. Never will Garth forget that terrible moment! Often, long afterwards, he would awake, trembling in every limb, from some hideous dream, wherein he was once more at close grips with the loathsome inhabitants of the subterranean river. The whole thing was a nightmare of glaring eyes and grabbing, misshapen limbs, and through it all the inventor, scarcely yet recovered from his long period of insensibility, was conscious of but one thing, the intermittent cracking of the millionaire’s weapons. The turret was filled with smoke, through which the ghastly forms of the attackers loomed monstrous and terrible. Suddenly the sound of Haverly’s revolvers ceased: his last chamber was empty! But the creatures had had enough. Eight of their number lay dead, while two or three of the rest were badly wounded, and, obeying a common impulse, they dragged themselves through the doorway, shambled across the deck, and plunged overboard. “Thank Heaven!” Haverly’s voice was a trifle shaky as he mopped his smoke-grimed brow. “Amen!” Garth responded fervently; then, fearing that his nerve would give way unless he exerted himself, he applied his energies to the restoration of his unconscious friends; while the Yankee, dragging the hideous relics of the narrowly-averted disaster to the rail, flung them far out into the stream. Soon Garth had the satisfaction of seeing his three friends once more upon their feet. Badly shaken they were by their terrible plunge over the cataract, yet thankful that they had been spared the ordeal which had fallen to the lot of Garth and the Yankee. “I guess there’s no call to make a fuss,” the latter said as they crowded round him. “I couldn’t have been knocked about so badly as you, or I wouldn’t have come to in time to check those brutes.” “Thank God you did!” the scientist cried. “This must be a warning to us in the future. Knowing that this subterranean river contains such monstrous creatures, we must be ever upon our guard, lest upon another occasion they should succeed in overcoming us.” His listeners shuddered at his words. Though none but Silas and the inventor had seen the river-creatures--mud devils, Garth called them--yet the latter’s vivid description of the things had aroused in the three an unspeakable horror and loathing.