In the shoal water over the broad banks which lay to the south and east of the Irene the bayonet fins of many tarpon rose high above the surface as the fish beneath them pursued their prey.  Often the two fins shown by a wandering shark swept swiftly across a bank, or three big reddish fins moving in a straight line slowly behind a great, swaying, four-foot weapon marked the course of a fifteen-foot sawfish.  There was water to float the power boat in the channels between the banks, and families of porpoises or dolphins were always ready to serve as pilots and point the path through these labyrinthine waterways.  A school of porpoises, rolling in the water and leaping in the air, passed the motor boat as if they had been telephoned for in the greatest haste.  Two minutes later, a quarter of a mile away, a great splashing could be seen and huge bodies hurled in the air, which seemed to be filled with flying fragments.

The power boat, with Molly at the wheel, started for the fray at its best speed and when it reached the battlefield its occupants saw a little band of porpoises in the midst of a great school of silver mullet.  Each blow of a porpoise tail sent several mullet flying in the air, each blow that was struck was followed by a quick turn or leap of the agile animal for the victim which it caught before it fell.  Ned and Dick were in the skiff which had been towed by the power boat, hoping to harpoon a sawfish or a shark.  They had not before thought of the swift and wary porpoise.  They called to the captain to cast them loose, and soon Ned was poling the skiff toward the busy porpoises while Dick stood in the bow of the skiff with his harpoon handy.  Quick as a flash the porpoises separated and scattered in every direction and the boys followed several in vain.  Then Molly took a hand in the game and sent the power boat at one after another of them until the captain called to her: 

“If you’ll stick to one you’ll run him down.”

Then Molly kept steadily after a single porpoise, until the animal came to understand that it was the chosen victim, and quickly put half a mile between it and its pursuer.  In a few minutes the half mile between them had vanished and the creature made another frantic dash.  After that it swam back and forth as if confused, and traveled in narrowing circles, wasting its strength, while the wheel of the pursuing boat rolled back and forth without ceasing as it followed the course of the animal or took short cuts to head it off.  The boys came near with the skiff, but the worried quarry paid so little heed to them that soon Dick sunk his harpoon in the tail of the porpoise.  All the life and strength of the creature seemed to come back and it threw a column of water in the air which nearly swamped the skiff, while Dick’s hands were torn and blistered by the outgoing harpoon line, before way could be had on the skiff.  The frantic creature tore back and forth, sometimes striking the skiff a powerful blow with its tremendous tail as it passed, sometimes towing it at high speed until Dick, who was not yet strong, was more tired than the porpoise.  He changed places with Ned and the two were nearly worn out when the porpoise surrendered.