h Tom and his friends. Nearly half of Koku's great
strength was wasted. But they knew they could take their time, though
they did not want to waste many hours.

The streamers of weed were like strands of tightly wound rope, and
this, under certain circumstances, acquires almost the density of wood.
Tom and Ned, working together, had managed to chop a little off their
propeller shaft, and Koku had done somewhat better with his task, when
Ned became aware of a shadow passing above him.

Instinctively he looked up, and as he did so he could not repress a
start of horror. Tom, too, as well as Koku, saw the menacing shadow.
Ned grasped more tightly his sharp, steel bar and spoke through the
telephone to his companions.

"Devil fish!" he said. "The devil fish are after us."

CHAPTER XXI

A WAR REMINDER

To a large number of people the name devil fish brings to mind a
conception of an octopus, squid, cuttle fish, or a member of that
species. This is, however, a mistake.

The true devil fish of the tropics is a member of the sting ray family,
and the common name it bears is given to it because of two prongs, or
horns, which project just in front of its mouth. His Satanic Majesty
is popularly supposed to have horns, together with a tail, hoofs and
other appendages, and the horns of this sting ray fish are what give it
the name it bears.

The devil fish, some specimens of which grow to the weight of a ton and
measure fifteen feet from wing tip to wing tip, are armed with a long
tail, terminating in a tough, horny substance, like many of the ray
family members. This horn-tipped tail, lashing about in the water,
becomes a terrible weapon of defense. Possibly it is used for offense,
as the devil fish feeds on small sea animals, sweeping them into its
mouth by movements of the horns mentioned. These horns, swirled about
in the water, create a sort of suction current, and on that the food
fishes are borne into the maw of the gigantic creature.

A whale rushes through a school of small sea animals with open mouth,
takes in a great quantity of water, and the fringe of whalebone acts as
a strainer, letting out the water and retaining the food. In like
manner the devil fish feeds, except that it has no whalebone. Its
"horns" help it to get a meal.

The "wing tips" of the devil fish have been spoken of. They are not
really wings, though when one of these fish breaks water and shoots
through the air, it appears to be