“Imitations, undoubtedly,” was the reply of Mr. Jesson. “The tribe that owned the genuine stones adopted this cunning means of concealing the real ones by coating them with wax of some sort. Then they placed inferior gems, or cunning imitations, within the box, trusting to the cupidity of any one who stole them not to investigate further.” And so it proved afterward. The stones, which the strange and seemingly trivial accident had revealed, turned out to be as fine specimens of their respective kinds as there are in existence. They were appraised at six hundred and eighty thousand dollars, but cryptic carvings on the back of them made them of infinitely more value to science as specimens of the treasures of a vanished race. Despite their keen excitement over the discovery that, after all, Herrera had not decamped with the precious stones, the adventurers slept soundly and peacefully that night. When they awakened the daylight was sparkling on land and sea, and Jupe was filling the air with appetizing aromas proceeding from his cooking fire. It was while they were in the midst of the morning meal that Jack sprang to his feet with a shout. “The _Sea King_! the _Sea King_!” he cried, pointing seaward. About half a mile off shore, steaming leisurely along, was a fine-looking white yacht that the Professor speedily pronounced to be, indeed, the _Sea King_. “The wireless, Tom, as quick as you can,” called Jack, and the two lads at once set about sending their life-jacket balloons aloft. This time the message that Jack sent out reached the persons it was intended for, and an hour later a boat came ashore and the castaways found themselves among their friends. Repairs had been effected in record time on the yacht, and those in charge of her had determined not to wait longer at Lone Island, but proceed south at once. They were urged to this course, also, by news from Mexico that the revolutionists had triumphed, and that Diaz had abdicated. We should like to chronicle more of the adventures of the Boy Inventors on this trip, but the exigencies of space forbid it. Suffice it to say then, that while the Professor, the rescued explorer and the rest, including Captain Andrews, voyaged to Lone Island and thence home on the _Sea King_, the boys drove the Flying Road Racer through Mexico, and reached home in that way by the overland route. They had many exciting times, but none so filled with peril and incident as their career on the gulf had been.