The Nile produces the crocodile, a destructive quadruped, and equally dangerous on land and in the water. This is the only land animal that does not enjoy the use of its tongue,[98] and the only one that has the upper jaw movable, and is capable of biting with it; and terrible is its bite, for the rows of its teeth fit into each other, like those of a comb. Its length exceeds eighteen cubits. It produces eggs about the size of those of the goose, and, by a kind of instinctive foresight, always deposits them beyond the limit to which the river Nile rises, when at its greatest height. There is no animal that arrives at so great a bulk as this, from so small a beginning. It is armed also with claws, and has a skin, that is proof against all blows. It passes the day on land, and the night in the water, in both instances on account of the warmth. When it has glutted itself with fish, it goes to sleep on the banks of the river, a portion of the food always remaining in its mouth; upon which, a little bird, which in Egypt is known as the trochilus, and, in Italy, as the king of the birds, for the purpose of obtaining food, invites the crocodile to open its jaws; then, hopping to and fro, it first cleans the outside of its mouth, next the teeth, and then the inside, while the animal opens its jaws as wide as possible, in consequence of the pleasure which it experiences from the titillation.[99] It is at these moments that the ichneumon, seeing it fast asleep in consequence of the agreeable sensation thus produced, darts down its throat like an arrow, and eats away its intestines.[100]

Like the crocodile, but smaller even than the ichneumon, is the scincus, which is also produced in the Nile, and the flesh of which is the most effectual antidote against poisons. But so great a pest was the crocodile to prove, that Nature was not content with giving it one enemy only; the dolphins, therefore, which enter the Nile, have the back armed with a spine,[101] which is edged like a knife, as if for this very purpose; and although these animals are much inferior in strength, they contrive to destroy the crocodile by artifice, which on the other hand attempts to drive them from their prey, and would reign alone in its river as its peculiar domain. For all animals have an especial instinct in this respect, and are able to know not only what is for their own advantage, but also what is to the disadvantage of their enemies; they fully understand the use of their own weapons, they know their opportunity, and the weak parts of those with which they have to contend.

The skin of the belly of the crocodile is soft and thin; aware of this, the dolphins plunge into the water, as if in great alarm, and diving beneath its belly, tear it open with their spines. There is a race of men also, who are peculiarly hostile to the crocodile; they are known as the TentyritÆ, from an island in the Nile which they inhabit. These men are of small stature, but of wonderful presence of mind, though for this particular object only. The crocodile is a terrible animal to those who fly from it, while at the same time it will fly from those who pursue it; these, however, are the only people who dare to attack it. They even swim in the river after it, and mount its back like so many horsemen; and just as the animal turns up its head for the purpose of biting them, they insert a club into its mouth, holding which at each end, with the two hands, it acts like a bit, and by these means they drive the captured animal on shore. They also terrify the crocodile so much even by their voice alone, as to force it to disgorge the bodies which it has lately swallowed, for the purpose of burial. This island, therefore, is the only place near which the crocodile never swims; for it is repelled by the odor of this race of men. The sight of the animal is said to be dull when it is in the water, but, when out of the water, piercing in the extreme; it always passes the four winter months in a cave, without taking food. Some persons say, that this is the only animal that continues to increase in size as long as it lives; it is very long-lived.

The Nile produces the hippopotamus, another wild beast, of a still greater size. It has the cloven hoof of the ox; the back, the mane, and the neighing of the horse; and the turned-up snout, the tail, and the hooked teeth of the wild boar, but is not so dangerous. The hide is impenetrable, except when it has been soaked with water; and it is used for making shields and helmets. This animal lays waste the standing corn, and determines beforehand what part it shall ravage on the following day; it is said also, that it enters the field backwards, to prevent any ambush being laid for it on its return.

Marcus Scaurus was the first to exhibit this animal at Rome, together with five crocodiles, at the games which he gave in his Ædileship, in a piece of water which had been temporarily prepared for the purpose. The hippopotamus has even been our instructor in one of the operations of medicine. When the animal has become too bulky by continued overfeeding, it goes down to the banks of the river, and examines the reeds which have been newly cut; as soon as it has found a stump that is very sharp, it presses its body against it, and so wounds one of the veins in the thigh; and, by the flow of blood thus produced, the body, which would otherwise have fallen into a morbid state, is relieved; after which, it covers up the wound with mud.