It was just at the time when this thought came that Ab saw the Shell girl lift her head and turn it toward him and laugh--laugh recklessly, almost in his very face, so close together were they now. And then she taught him something! There was a dip such as the otter makes when he seeks the depths and there was no longer a girl in sight! But this was only a demonstration, made in sheer audacity and blithesome insolence, for the brown head soon appeared again some yards ahead and there was another twist of it and another merry laugh. Then the neat body turned upon its side, and with quick outdriving legstrokes and the overhand and underhand pulling-forward which modern swimmers partly know, the girl shot ahead through the tiny white-capped waves and away from the swimmer so close behind her, as to-day the cutter leaves the scow. From the river bank came a wild yelp, the significance of which, if analyzed, might have included astonishment and great delight and brotherly derision. Oak was having a great day of it! He was the sole witness of a swimming-match the like of which was rare, and he was getting even with his friend for various assumptions of superiority in various doings. Unexhausted and sturdy and stubborn, Ab was not the one to abandon his long chase because of this new phase of things. He inhaled a great breath and made the water foam with his swift strokes, but as well might a wild goose chase a swallow on the wing as he seek to overtake that brown streak on the water. It was wonderful, the manner in which that Shell girl swam! She was like the birds which swim and dive and dip, and know of nothing which they fear if only they are in the water far enough away from where there is the need of stalking over soil and stone. It was not that the Shell girl was other than at home on land. She was quite at home there and reasonably fleet, but the creek and river had so been her element from babyhood that the chase of the hill man had been, from the start, a sheer absurdity. Ab lifted himself in the waters and gazed upon the dark spot far away, and, piqued and maddened, put forth all the swimming strength there was left in his brawny body. It seemed for a brief time that he was almost equal to the task of gaining upon what was little more than a dot upon the surface far ahead. But his scant prospect of success was only momentary. The trifling spot in the distant drifts of the river seemed to have certain ideas of its own. The speed of its course in the water did not abate and, in a moment, it was carried around the bend, and lost to sight. Ab drifted to the turn and saw, below, a girl clambering into safety among the rafts of the fishing Shell People. What she would tell them he did not know. That was not a matter to be much considered.