In half an hour all had arrived at the southeast angle of the lake, and were again upon Prospect Plateau. They had made the circle of the bank without the engineer having discovered either where or how the surplus water was discharged. “Nevertheless, this outlet exists,” he repeated, “and, since it is not outside, it must penetrate the massive granite of the coast!” “And why do you want to find that out?” asked Spilett. “Because,” answered the engineer, “if the outlet is through the solid rock it is possible that there is some cavity, which could be easily rendered habitable, after having turned the water in another direction.” “But may not the water flow into the sea, through a subterranean outlet at the bottom of the lake?” asked Herbert. “Perhaps so,” answered Smith, “and in that case, since Nature has not aided us, we must build our house ourselves.” As it was 5 o’clock, the colonists were thinking of returning to the Chimneys across the plateau, when Top again became excited, and, barking with rage, before his master could hold him, he sprang a second time into the lake. Every one ran to the bank. The dog was already twenty feet off, and Smith called to him to come back, when suddenly an enormous head emerged from the water. Herbert instantly recognized it, the comical face, with huge eyes and long silky moustaches. “A manatee,” he cried. Although not a manatee, it was a dugong, which belongs to the same species. The huge monster threw himself upon the dog. His master could do nothing to save him, and, before Spilett or Herbert could draw their bows, Top, seized by the dugong, had disappeared under the water. Neb, spear in hand, would have sprung to the rescue of the dog, and attacked the formidable monster in its own element, had he not been held back by his master. Meanwhile a struggle was going on under the water—a struggle which, owing to the powerlessness of the dog, was inexplicable; a struggle which, they could see by the agitation of the surface, was becoming more terrible each moment; in short, a struggle which could only be terminated by the death of the dog. But suddenly, through the midst of a circle of foam, Top appeared, shot upward by some unknown force, rising ten feet in the air, and falling again into the tumultuous waters, from which he escaped to shore without any serious wounds, miraculously saved. Cyrus Smith and his companions looked on amazed. Still more inexplicable, it seemed as if the struggle under water continued. Doubtless the dugong, after having seized the dog, had been attacked by some more formidable animal, and had been obliged to defend itself. But this did not last much longer. The water grew red with blood, and the body of the dugong, emerging from the waves, floated on to a little shoal at the southern angle of the lake.