On its borders dwell the Garamantians, a lightly clad, agile tribe of tent-dwellers subsisting mainly by the chase. These are the only people who occasionally penetrate the desert, in pursuit of game. They wait till rain falls, about the winter solstice, mitigating the excessive heat, moistening the sand, and making it just passable. Their quarry consists chiefly of wild asses, the giant ostrich that runs instead of flying, and monkeys, to which the elephant is sometimes added; these are the only creatures sufficiently proof against thirst and capable of bearing that incessant fiery sunshine. But the Garamantians, as soon as they have consumed the provisions they brought with them, instantly hurry back, in fear of the sand's recovering its heat and becoming difficult or impassable, in which case they would be trapped, and lose their lives as well as their game. For if the sun draws up the vapour, dries the ground rapidly, and has an access of heat, throwing into its rays the fresh vigour derived from that moisture which is its aliment, there is then no escape. But all that I have yet mentioned, heat, thirst, desolation, barrenness, you will count less formidable than what I now come to, a sufficient reason in itself for avoiding that land. It is beset by all sorts of reptiles, of huge size, in enormous numbers, hideous and venomous beyond belief or cure. Some of them have burrows in the sand, others live on the surface--toads, asps, vipers, horned snakes and stinging beetles, lance-snakes, reversible snakes[3], dragons, and two kinds of scorpion, one of great size and many joints that runs on the ground, the other aerial, with gauzy wings like those of the locust, grasshopper, or bat. With the multitude of flying things like these, that part of Libya has no attraction for the traveller. But the direst of all the reptiles bred in the sand is the dipsas or thirst-snake; it is of no great size, and resembles the viper; its bite is sharp, and the venom acts at once, inducing agonies to which there is no relief. The flesh is burnt up and mortified, the victims feel as if on fire, and yell like men at the stake. But the most overpowering of their torments is that indicated by the creature's name. They have an intolerable thirst; and the remarkable thing is, the more they drink, the more they want to drink, the appetite growing with what it feeds on. You will never quench their thirst, though you give them all the water in Nile or Danube; water will be fuel, as much as if you tried to put out a fire with oil. Doctors explain this by saying that the venom is originally thick, and gains in activity when diluted with the drink, becoming naturally more fluid and circulating more widely.