"Some people call the octopus a devil-fish," said Mr. Choate. "This is all wrong. They are both large and vicious creatures, but entirely different in looks. The devil-fish belongs to the ray family, and, as you see, is a huge bat-like creature which uses its body fins with a waving, undulating motion, and propels itself through the water at remarkable speed." "It is built on the principle of our airplane--in looks," said Tom with a grin; "and in speed, too." "So it is," responded Mr. Choate. "It derives its satanic name from these cephalic fins or lobes which extend outward and upward from each side of its flat head, like curling horns. When it dashes into a school of smaller fish, these fins whirl about in every direction, and as they are often four feet long they easily reach more than one hapless fish and he is swept into the yardwide mouth of the monster and devoured with almost lightning speed." After a rest, the party went out in the motorboat again, this time to catch foodfish. They had fine luck, and after an appetizing meal aboard the _L'Apache_, in which their small catch played an important part, all set out for Miami, tired and happy. CHAPTER XIII THE STRANGE AIRPLANE The first thing the boys did the following morning, after spending the night at the home of Mr. Choate, was to go down to the beach and see if their airplane was all right. They found one of the two negroes asleep, but the other fellow was faithfully on guard, and everything about the Sky-Bird seemed just as they had left it, although the watchers said that a considerable number of curious townspeople had come to look at the machine the day before and they had been very busy keeping venturesome boys off the craft. Our friends let the negroes go to get their breakfasts and some sleep, and engaged two others to take up the watch. Following this, in company with Mr. Choate, they all retired to the bathhouse, secured bathing suits and had a fine time disporting themselves in the warm surf for the next hour. The youths had never experienced Gulf Stream bathing before, and the water was so enticing that it was hard to drag themselves out of it. As they were in the act of emerging to dress themselves, a black speck, which all had noticed in the northern sky, had developed by nearer approach so that they thought they could recognize it as an airplane. It was coming down the coast very rapidly. Wondering if its pilot intended to land in the vicinity, they gathered on the beach and curiously waited for it to come nearer. At times they were puzzled to know whether the approaching object were really an airplane or a great bird, for it surely looked like a bird with its swelling breast-line and slightly tilted broad-shouldered wings. Closer and closer it came. It was flying very high. When it was almost over them, Mr. Giddings uttered a startled ejaculation; "My stars, boys! It's _our_ machine!"