11. This river, rising as I have said, is driven on from the marshes to the cataracts, and forms several islands; some of which are said to be of such extent that the stream is three days in passing them. 12. Among these are two of especial celebrity, Meroe and Delta. The latter derives its name from its triangular form like the Greek letter; but when the sun begins to pass through the sign of Cancer, the river keeps increasing till it passes into Libra; and then, after flowing at a great height for one hundred days, it falls again, and its waters being diminished it exhibits, in a state fit for riding on, fields which just before could only be passed over in boats. 13. If the inundation be too abundant it is mischievous, just as it is unproductive if it be too sparing; for if the flood be excessive, it keeps the ground wet too long; and so delays cultivation; while if it be deficient, it threatens the land with barrenness. No landowner wishes it to rise more than sixteen cubits. If the flood be moderate, then the seed sown in favourable ground sometimes returns seventy fold. The Nile, too, is the only river which does not cause a breeze. 14. Egypt also produces many animals both terrestrial and aquatic, and some which live both on the earth and in the water, and are therefore called amphibious. In the dry districts antelopes and buffaloes are found, and sphinxes, animals of an absurd-looking deformity, and other monsters which it is not worth while to enumerate. 15. Of the terrestrial animals, the crocodile is abundant in every part of the country. This is a most destructive quadruped, accustomed to both elements, having no tongue, and moving only the upper jaw, with teeth like a comb, which obstinately fasten into everything he can reach. He propagates his species by eggs like those of a goose. 16. And as he is armed with claws, if he had only thumbs his enormous strength would suffice to upset large vessels, for he is sometimes ten cubits long. At night he sleeps under water; in the day he feeds in the fields, trusting to the stoutness of his skin, which is so thick that missiles from military engines will scarcely pierce the mail of his back. 17. Savage as these monsters are at all other times, yet as if they had concluded an armistice, they are always quiet, laying aside all their ferocity, during the seven days of festival on which the priests at Memphis celebrate the birthday of Apis. 18. Besides those which die accidentally, some are killed by wounds which they receive in their bellies from the dorsal fins of some fish resembling dolphins, which this river also produces.