He barked with fury, and before his master could restrain him, he had plunged a second time into the lake.

All ran towards the bank. The dog was already more than twenty feet off, and Cyrus was calling him back, when an enormous head emerged from the water, which did not appear to be deep in that place.

Herbert recognized directly the species of amphibian to which the tapering head, with large eyes, and adorned with long silky mustaches, belonged.

"A lamantin!" he cried.

It was not a lamantin, but one of that species of the order of cetaceans, which bear the name of the "dugong," for its nostrils were open at the upper part of its snout. The enormous animal rushed on the dog, who tried to escape by returning towards the shore. His master could do nothing to save him, and before Gideon Spilett or Herbert thought of bending their bows, Top, seized by the dugong, had disappeared beneath the water.

Neb, his iron-tipped spear in his hand, wished to go to Top's help, and attack the dangerous animal in its own element.

"No, Neb," said the engineer, restraining his courageous servant.

Meanwhile, a struggle was going on beneath the water, an inexplicable struggle, for in his situation Top could not possibly resist; and judging by the bubbling of the surface it must be also a terrible struggle, and could not but terminate in the death of the dog! But suddenly, in the middle of a foaming circle, Top reappeared. Thrown in the air by some unknown power, he rose ten feet above the surface of the lake, fell again into the midst of the agitated waters, and then soon gained the shore, without any severe wounds, miraculously saved.

Cyrus Harding and his companions could not understand it. What was not less inexplicable was that the struggle still appeared to be going on. Doubtless, the dugong, attacked by some powerful animal, after having released the dog, was fighting on its own account. But it did not last long. The water became red with blood, and the body of the dugong, emerging from the sheet of scarlet which spread around, soon stranded on a little beach at the south angle of the lake. The colonists ran towards it. The dugong was dead. It was an enormous animal, fifteen or sixteen feet long, and must have weighed from three to four thousand pounds. At its neck was a wound, which appeared to have been produced by a sharp blade.

What could the amphibious creature have been, who, by this terrible blow had destroyed the formidable dugong? No one could tell, and much interested in this incident, Harding and his companions returned to the Chimneys.

Chapter 17

The next day, the 7th of May, Harding and Gideon Spilett, leaving Neb to prepare breakfast, climbed Prospect Heights, while Herbert and Pencroft ascended by the river, to renew their store of wood.

The engineer and the reporter soon reached the little beach on which the dugong had been stranded. Already flocks of birds had attacked the mass of flesh, and had to be driven away with stones, for Cyrus wished to keep the fat for the use of the colony. As to the animal's flesh it would furnish excellent food, for in the islands of the Malay Archipelago and elsewhere, it is especially reserved for the table of the native princes. But that was Neb's affair.

At this moment Cyrus Harding had other thoughts. He was much interested in the incident of the day before. He wished to penetrate the mystery of that submarine combat, and to ascertain what monster could have given the dugong so strange a wound. He remained at the edge of the lake, looking, observing; but nothing appeared under the tranquil waters, which sparkled in the first rays of the rising sun.

At the beach, on which lay the body of the dugong, the water was tolerably shallow, but from this point the bottom of the lake sloped gradually, and it was probable that the depth was considerable in the center. The lake might be considered as a large center basin, which was filled by the water from the Red Creek.

"Well, Cyrus," said the reporter, "there seems to be nothing suspicious in this water."

"No, my dear Spilett," replied the engineer, "and I really do not know how to account for the incident of yesterday."

"I acknowledge," returned Spilett, "that the wound given this creature is, at least, very strange, and I cannot explain either how Top was so vigorously cast up out of the water.