taken--and it was within the range
of probability and possibility that we were not making our way through
the strata of rocks which I believed I recognized piled on the lower
layer of granitic formation.

"At all events, if I am right," I thought to myself, "I must certainly
find some remains of primitive plants, and it will be absolutely
necessary to give way to such indubitable evidence. Let us have a good
search."

I accordingly lost no opportunity of searching, and had not gone more
than about a hundred yards, when the evidence I sought for cropped up in
the most incontestable manner before my eyes. It was quite natural that
I should expect to find these signs, for during the Silurian period the
seas contained no fewer than fifteen hundred different animal and
vegetable species. My feet, so long accustomed to the hard and arid lava
soil, suddenly found themselves treading on a kind of soft dust, the
remains of plants and shells.

Upon the walls themselves I could clearly make out the outline, as plain
as a sun picture, of the fucus and the lycopods. The worthy and
excellent Professor Hardwigg could not of course make any mistake about
the matter; but I believe he deliberately closed his eyes, and continued
on his way with a firm and unalterable step.

I began to think that he was carrying his obstinacy a great deal too
far. I could no longer act with prudence or composure. I stooped on a
sudden and picked up an almost perfect shell, which had undoubtedly
belonged to some animal very much resembling some of the present day.
Having secured the prize, I followed in the wake of my uncle.

"Do you see this?" I said.

"Well, said the Professor, with the most imperturbable tranquillity, "it
is the shell of a crustaceous animal of the extinct order of the
trilobites; nothing more, I assure you."

"But," cried I, much troubled at his coolness, "do you draw no
conclusion from it?"

"Well, if I may ask, what conclusion do you draw from it yourself?"

"Well, I thought--"

"I know, my boy, what you would say, and you are right, perfectly and
incontestably right. We have finally abandoned the crust of lava and the
road by which the lava ascended. It is quite possible that I may have
been mistaken, but I shall be unable to discover my error until I get to
the end of this gallery."

"You are quite right as far as that is concerned," I replied, "and I
should highly approve of your decision, if we had not to fear the
g