suddenly came to a
full stop.

"I do not understand the presence of such beasts in granite caverns,
however vast and prodigious," was my reply.

"Why not?" said my uncle, with very much of his old professional
impatience.

"Because it is well known that animal life only existed on earth during
the secondary period, when the sedimentary soil was formed by the
alluviums, and thus replaced the hot and burning rocks of the primitive
age."

"I have listened to you earnestly and with patience, Harry, and I have a
simple and clear answer to your objections: and that is, that this
itself is a sedimentary soil."

"How can that be at such enormous depth from the surface of the earth?"

"The fact can be explained both simply and geologically. At a certain
period, the earth consisted only of an elastic crust, liable to
alternative upward and downward movements in virtue of the law of
attraction. It is very probable that many a landslip took place in those
days, and that large portions of sedimentary soil were cast into huge
and mighty chasms."

"Quite possible," I dryly remarked. "But, Uncle, if these antediluvian
animals formerly lived in these subterranean regions, what more likely
than that one of these monsters may at this moment be concealed behind
one of yonder mighty rocks."

As I spoke, I looked keenly around, examining with care every point of
the horizon; but nothing alive appeared to exist on these deserted
shores.

I now felt rather fatigued, and told my uncle so. The walk and
excitement were too much for me in my weak state. I therefore seated
myself at the end of a promontory, at the foot of which the waves broke
in incessant rolls. I looked round a bay formed by projections of vast
granitic rocks. At the extreme end was a little port protected by huge
pyramids of stones. A brig and three or four schooners might have lain
there with perfect ease. So natural did it seem, that every minute my
imagination induced me to expect a vessel coming out under all sail and
making for the open sea under the influence of a warm southerly breeze.

But the fantastic illusion never lasted more than a minute. We were the
only living creatures in this subterranean world!

During certain periods there was an utter cessation of wind, when a
silence deeper, more terrible than the silence of the desert fell upon
these solitary and arid rocks--and seemed to hang like a leaden weight
upon the waters of this singular ocean. I so