set the hilt
of his knife between his teeth, and prepared to plunge in. Before doing
so, however, he instinctively scanned the water all about him. Then he
removed the knife from his mouth and stared.

"That accounts for it!" he muttered, his teeth baring themselves with a
snarl of loathing as he thrust the knife back into his belt and sat down
again. Just behind him, and not a dozen feet away, a gigantic,
triangular black fin was slowly cleaving the swells.

There being nothing else to do, Mahoney occupied himself in watching
that great dorsal, as it prowled slowly this way and that. Such a fin,
he calculated, must mean a bigger shark than any that had hitherto come
within his range of observation. He had a righteous hatred of all
sharks, but this one in particular sickened him with vindictive
loathing. He knew how lately, and how horridly, it had fed; yet here it
was as ravenous as ever. Presently it sank out of sight, and was gone
for perhaps ten or fifteen minutes. Then, on a sudden, there was the
devilish black fin again, vigilant and deliberate.

[Illustration: "LAY MOTIONLESS BUT FOR THE EASY WAVING OF ITS FINS."]

As the sun rose, and the light fell more steeply, the dazzling
reflections disappeared and Mahoney could look down into the transparent
blue-green depths. He saw that the wreck on which he had taken refuge
was an old one, long adrift in the teeming tropic seas. Its under edges
carried a dense, waving fringe of barnacles and coloured weed,
swarming with sea-creatures. In its shadow life crowded riotously, and
death held easy revel. Among the looser fringes of the barnacle growth
swam fish of the smaller species, many of them flashing with the
radiance of sapphire and topaz, or shooting like pink flames. Hither and
thither darted a small school of blue and gold bonito, insatiable and
swift, snatching down their prey from among the tips of the barnacles.
About six feet below the barnacles a cavernous-jawed barracouta, perhaps
five feet long, lay motionless but for the easy waving of its fins. It
must have been gorged, for Mahoney, in all his seafaring, had never
before seen one of these ravenous and ferocious fish thus at rest. It
must even have, for once, lapsed into something like sleep,--a perilous
lapse in the strenuous life of the sea, for anything less formidable
than a sperm whale or an orca, and not without its dangers even for
them. Its wide-set, staring eyes seemed to command a view in every