"Hark! There was a rustling sound over our heads. It grew louder and louder, until we could not hear each other's voices. As we looked up into the darkness, we could see we had startled an army of bats. There were thousands of them. Yes, surely, many thousands. You wouldn't have enjoyed their flying around you one bit, Manuel, good little huntsman even as you are. And as for you, my precious Dolores, I fear you would have screamed and begged to be taken home. "Over our heads we could hear the sound of running water all the time. We kept bravely on. It began to grow lighter, and we could see several openings in front of us. Choosing one of these, we crept through a narrow passage and found ourselves at once in a vast hall. It was like Aladdin's palace, which, you remember, was brilliant with beautiful gems. "I looked up to the high roof and saw hundreds of sparkling white pendants. Some of them were quite small, but others reached down so far that I could touch them. They shone like the finest marble. They were made by the water trickling through the roof and leaving particles of lime as it slowly made its way downward. Such pendants are called stalactites. Some of them were tinted a beautiful blue or green. This was because the water had passed through some mineral substance of those colours. "And the walls of that hall! Sparkling white columns reached from the floor to the very dome. They were fluted and worked in the most delicate patterns. I can never forget that wonderful picture. "But what ugly creatures made their home in this wonderful palace of Mother Nature? They were land-crabs, to be sure, that tried to get out of our way as fast as their clumsy feet would permit. It was your story of the crabs, Manuel, that made me think of that day's tramp. "You can hardly believe it, children, but we passed from one such hall to another until we had travelled at least a mile underground. Here and there were dark holes leading farther down yet. We could look over the edge sometimes and see other great hallways directly under where we were. The guides said: "'No, no, you must not try to reach them. You may never get back.' "But I insisted on going into one, at least. A stout rope was fastened about my waist; two men held it tightly, and gradually let me go. Down I went, down, down, down. Would I never reach the bottom? I was growing a little scared, when I found myself on the floor of another great hall, much like the one above it. I groped about and relighted my torch, which had gone out as I was lowered through the damp air. "I found myself beside a stream of running water. It was flowing right by the doorway into the cave. I had heard there was just such an entrance as this,--that down on the side of the mountain a person could get into the cavern by first passing through the water.