"Wonderful, magnificent, splendid!" cried my uncle. "Here is the entire flora of the second period of the world - the transition period. These, humble garden plants with us, were tall trees in the early ages. Look, Axel, and admire it all. Never had botanist such a feast as this!"
"You are right, my uncle. Providence seems to have preserved in this immense conservatory the antediluvian plants which the wisdom of philosophers has so sagaciously put together again."
"It is a conservatory, Axel; but is it not also a menagerie?"
"Surely not a menagerie!"
"Yes; no doubt of it. Look at that dust under your feet; see the bones scattered on the ground."
"So there are!" I cried; "bones of extinct animals."
I had rushed upon these remains, formed of indestructible phosphates of lime, and without hesitation I named these monstrous bones, which lay scattered about like decayed trunks of trees.
"Here is the lower jaw of a mastodon,"  I said. "These are the molar teeth of the deinotherium; this femur must have belonged to the greatest of those beasts, the megatherium. It certainly is a menagerie, for these remains were not brought here by a deluge. The animals to which they belonged roamed on the shores of this subterranean sea, under the shade of those arborescent trees. Here are entire skeletons. And yet I cannot understand the appearance of these quadrupeds in a granite cavern."
 These animals belonged to a late geological period, the Pliocene, just before the glacial epoch, and therefore could have no connection with the carboniferous vegetation. (Trans.)
"Because animal life existed upon the earth only in the secondary period, when a sediment of soil had been deposited by the rivers, and taken the place of the incandescent rocks of the primitive period."
"Well, Axel, there is a very simple answer to your objection that this soil is alluvial."
"What! at such a depth below the surface of the earth?"
"No doubt; and there is a geological explanation of the fact. At a certain period the earth consisted only of an elastic crust or bark, alternately acted on by forces from above or below, according to the laws of attraction and gravitation. Probably there were subsidences of the outer crust, when a portion of the sedimentary deposits was carried down sudden openings."
"That may be," I replied; "but if there have been creatures now extinct in these underground regions, why may not some of those monsters be now roaming through these gloomy forests, or hidden behind the steep crags?"
And as this unpleasant notion got hold of me, I surveyed with anxious scrutiny the open spaces before me; but no living creature appeared upon the barren strand.
I felt rather tired, and went to sit down at the end of a promontory, at the foot of which the waves came and beat themselves into spray. Thence my eye could sweep every part of the bay; within its extremity a little harbour was formed between the pyramidal cliffs, where the still waters slept untouched by the boisterous winds. A brig and two or three schooners might have moored within it in safety. I almost fancied I should presently see some ship issue from it, full sail, and take to the open sea under the southern breeze.
But this illusion lasted a very short time. We were the only living creatures in this subterranean world. When the wind lulled, a deeper silence than that of the deserts fell upon the arid, naked rocks, and weighed upon the surface of the ocean. I then desired to pierce the distant haze, and to rend asunder the mysterious curtain that hung across the horizon. Anxious queries arose to my lips. Where did that sea terminate? Where did it lead to? Should we ever know anything about its opposite shores?
My uncle made no doubt about it at all; I both desired and feared.
After spending an hour in the contemplation of this marvellous spectacle, we returned to the shore to regain the grotto, and I fell asleep in the midst of the strangest thoughts.