As soon as we arrived, Lucien had the satisfaction of trying one of our flambeaux. The branch crackled when lighted, and, as we entered the cavern, five or six bats flew out. I led Lucien by the hand, and very soon he was the only one who could stand upright. Afterwards we entered a vast chamber with a dome-shaped roof, which became lower the farther we penetrated; this was rather a disappointment, as we had fancied there was something more to be seen than a mere cave. A heap of reddish earth in one corner attracted Sumichrast's attention, who examined it to see if he could discover some fossil bones. Standing all together, we must have formed, by the smoky light of our odoriferous torches, rather a fantastic-looking group. More than half an hour elapsed without discovering any results from our digging. L'Encuerado, who had tried to crawl in between the roof and the ground, suddenly raised an exclamation; he had, in fact, all but fallen into a deep pit. In an instant I was laid down flat on my stomach and crawling towards the Indian; Lucien, owing to his size, was able to creep on his hands and feet, and consequently soon got in front of me. We could soon see down into the bottom of the hole; the burning fragments of our torches fell upon a heap of stones at a depth of twelve or fifteen feet. L'Encuerado threw one of the torches into the chasm, and the vague glimmer showed us a yawning opening on the left. Delighted with this discovery, we now beat a retreat, deferring a more thorough exploration until the next day. The night was dark, and during our absence the fire had almost gone out. Just below us, a tree, the outline of which we could scarcely distinguish, seemed covered with animated sparks. Lucien opened his eyes very widely indeed, not being in the least able to understand this phenomenon, which was produced by thousands of _elaterides_, insects which have on each side of the thorax a yellowish spot which becomes luminous in the dark. Nothing could be more curious than to see innumerable glittering spots rising, falling, and crossing one another with extraordinary rapidity; one might have fancied it a tree bearing flowers of fire waving about in the breeze. L'Encuerado came up with a specimen, which lighted up his hand with a greenish glimmer. Lucien took possession of it, and the two luminous spots looked to him like two enormous eyes. Suddenly the insect gave a kind of shock to the boy's fingers, who looked at us full of surprise.