Herodotus, the "Father of History," tells a curious story about the crocodile and the Nile bird. He says, "When the crocodile takes his food in the Nile, the interior of its mouth is always covered with flies. All birds with one exception flee from the crocodile: but this one bird, the Nile bird, far from avoiding it, flies towards the reptile with the greatest eagerness, and renders it a very essential service. Every time the crocodile goes on shore to sleep, and at the moment when it lies extended, with open jaws, the Nile bird enters the mouth of the terrible animal and delivers it from the flies that it finds there. The crocodile shows its recognition of the service by never harming the bird." I have heard that the flies which molest the crocodile are gnats, and their devourer a kind of plover. Near Karachi, in India, there is a swamp caused by hot springs, which is inhabited by crocodiles. There are over two hundred in the tank, which has been walled in, as they are considered sacred creatures. Buffaloes stand in the water unharmed, but any other animal which came within reach would be instantly devoured. A rash young Englishman once made the tour of this tank, alive with crocodiles, by walking on their horny backs! Alligator is only the Spanish name for all lizards, so called in allusion to their having legs like arms. The great American lizard, known by this name, is not so large as the crocodile; it loves heat, and will bury itself in the mud in cold weather. It feeds mostly upon fish, and will drive them before it in a shoal, until they have got into some creek or narrow bend of the river, and then stun them by blows of its great tail. Mr. Waterton, who knew the South American rivers so well, tells us that he once came upon what he thought a pretty sight--a number of young alligators, about a foot long, playing about on the sand like so many rabbits. He also tells a story, which might have had a sad ending, saying [Footnote: _Life of Charles Waterton_, p.56] that when he was anxious to secure an alligator, which he much wished to stuff, with its tough skin uninjured, he would not allow his men to shoot at him, but actually jumped upon his horny back and rode him along the sandy river-bank until the poor creature was tired out, and the daring rider secured his prize. I daresay yon would like to see the picture which one of his friends made of him, riding upon his dangerous steed. We may form some idea of this naturalist's feat from what he tells us in another part of his book about his "wanderings." "One Sunday afternoon," he says, "when a good many people were standing about on the banks of the Orinoco, never dreaming of danger, a great Cayman came suddenly out of the river, seized a man, and carried him off beneath the water, so that he was seen no more."