be afther wishing to have one of us?" asked Desmond. "Then I
hope you'll be mistaken; unless, Billy, you wish to be kind to the
baste, and let him have your arm as a treat."

"Thank you," said Billy; "I'd rather not. It wouldn't give him much
trouble to bite it off, though."

"We must not be disappointed in our expectation of exploring the cavern
by a brute like that," exclaimed Tom. "Hand me the boat-hook."
Standing up, he struck the point with all his might against the nose of
the monster, which at that instant sank with a suddenness which made Tom
lose his balance, and had not Desmond and Billy seized him he would have
been overboard.

"He's more afraid of us than we are of him," said Tom. "Now let us get
as far up the cavern as we can."

They pulled cautiously on, Tim standing up in the bows, and feeling
ahead with the boat-hook. The mouth of the cavern seemed to grow
smaller and smaller, until only a point of light remained. Suddenly Pat
Casey, who was pulling with Jerry Bird, declared that he felt something
seize the blade of his oar.

"It's the shark, perhaps," said Tom. "We have the muskets ready. I'll
give him a shot, and that will make him keep his distance. Wait until
he tries it again."

Tom took the musket, and stood up ready to fire.

"There! he's got my oar in his jaws," cried Pat.

Tom fired. The flash revealed for an instant the sides and roof of the
cavern, which seemed to glitter as if studded with thousands of jewels,
while ahead all was pitchy darkness, showing that they had not yet got
to the extremity. The sound of the report, greatly increased in
loudness, went echoing amid the arches and pillars, until it died away
in the far distance, proving the great extent of the cavern.

Whether the shark was hit or not, it was impossible to say; but the
bullet tore off the point of Pat's oar, showing that Tom had taken good
aim.

Jerry Bird now suggested to the midshipmen that it would be prudent to
pull back, as without torches they could not see where they were going.
There might be, for what they could tell to the contrary, some big sea
monster squatting up at the further end, who might crunch them up
without ceremony.

Though Tom had no apprehensions on that score, he agreed to return,
proposing, should the _Dragon_ remain at anchor another day, to explore
the cave with a supply of torches. The boat was accordingly cautiously
pulled round, and made her way towards the mouth.