"Only with the greatest caution," returned I; "it is far too formidable, and too tenacious of life, for us rashly to attempt its destruction. Thank God, we are at Rockburg, where we can keep in safe retreat, while we watch for an opportunity to destroy this frightful enemy. Go up to your mother now, and assist in preparing the firearms; I will join you directly, but I must further observe the monster's movements." Fritz left me unwillingly, while I continued to watch the serpent, which was of gigantic size, and already much too near the bridge to admit of the possibility of removing that means of access to our dwelling. I recollected, too, how easily it would pass through the walls. The reptile advanced with writhing and undulatory movements, from time to time rearing its head to the height of fifteen or twenty feet, and slowly turning it about, as though on the lookout for prey. As it crossed the bridge, with a slow, suspicious motion, I withdrew, and hastily rejoined my little party, which was preparing to garrison our fortress in warlike array, but with considerable trepidation, which my presence served in a measure to allay. We placed ourselves at the upper openings, after strongly barricading everything below, and, ourselves unseen, awaited with beating hearts the further advance of the foe, which speedily became visible to us. Its movements appeared to become uncertain, as though puzzled by the trace of human habitation; it turned in different directions, coiling and uncoiling, and frequently rearing its head, but keeping about the middle of the space in front of the cave, when suddenly, as though unable to resist doing so, one after another the boys fired, and even their mother discharged her gun. The shots took not the slightest effect beyond startling the monster, whose movements were accelerated. Fritz and I also fired with steadier aim, but with the same want of success, for the monster, passing on with a gliding motion, entered the reedy marsh to the left, and entirely disappeared. A wonderful weight seemed lifted from our hearts, while all eagerly discussed the vast length and awful though magnificent appearance of the serpent. I had recognized it as the boa constrictor. It was a vast specimen, upward of thirty feet in length. I explained to the children that its name in South America is Boaguacu; the first syllable of that word, with the Latin addition, which indicates that it kills its prey by pressure, or "constriction," gives the name by which it is commonly known. The near neighborhood of this terrific reptile occasioned me the utmost anxiety; and I desired that no one should leave the house on any pretext whatever, without my express permission. During three whole days we were kept in suspense and fear, not daring to stir above a few hundred steps from the door, although during all that time the enemy showed no sign of his presence.