"Only in the absence of water. Grasses, cacti, and shrubbery not needing much moisture grow there. One of the geological surveys calls it Cactus Plain. It is one hundred miles long. There is water in a fissure of a mountain spur on one side called Cisternas Negras, or Black Tanks; but for the rest of the distance there was formerly no water except after a great rainfall in the depressions, a supply that quickly evaporates under a hot sun and in a dry atmosphere. A man named Tyson has lately sunk two wells thirty miles this side of La Paz." "It was at the Black Tanks the expressman saw Texas Dick and Juan Brincos with our ponies," said Henry. "What a queer name that is--Juan Brincos, John Jumper, or Jumping Jack, as nearly every one calls him." "He is well named; he has been jumping government stock for some years." "I thought Western people always hung horse-thieves." "Not when they steal from the government. They are apt to look upon army mules and horses as common property." "Frank," said Henry, just before the boys fell asleep that night, "I felt almost sure we should recapture the ponies when I thought Vic was going; but now I'm afraid we never shall see them again." [TO BE CONTINUED.] [Illustration: Queer Pets of Sailor Jack.] BY LIEUTENANT-COMMANDER J. D. JERROLD KELLEY, U.S.N. (_In Two Instalments._) II. A ship rat is not usually a cherished object of affection, but I knew of one, and here is the outline of his story: Once, in the quarterly overhauling of a frigate's main hold, a rat but a few days old was the only inmate found of a predatory colony which had scurried, been captured, or been carried away when the invaders entered. The ship's doctor, a tender soul, took nest and all to his room, rigged a crude but adequate feeding arrangement, and nursed and strengthened the baby rat into a healthy childhood. Nothing could have been tamer than the little gray creature, and it thrived lustily. It slept in the doctor's room, but made rambling adventures through the civilized plains of the ship, fearsomely avoiding the wilderness and deserts closed to man in the frames and timbers of her hull. At night it always awoke when the doctor came on shipboard, waited for a little food and fondling, and then slept peacefully until reveille sent it scampering to the steward for its breakfast. It kept the doctor's quarters clear of all winged insects, and made such a riot among the ants and roaches of the ward-room that the executive officer and mess caterer numbered it among their most efficient aids. It is unnecessary to say that no cats were allowed aft, and that the license and liberties of the officers' quarters were the cherished pleasure and hunting preserves of the rodent. Its affection for the doctor was unbounded, and it shared a particular fondness for the photographs of his children, peering through the glass at their innocent faces, and making a vantage-ground for its mid-day naps upon