"Try to conceal your natural ignorance," rejoined Merritt, with withering scorn. "He said, 'Mira qui.' That means 'Look here.'" "Oh, and 'latcha-key' means open the door, I suppose," retorted the stout youth. "You're a fine Spanish scholar, you are." "I've a good mind to throw you into that hole," threatened Merritt. "Try it," shouted the stout youth, hopping about aggravatingly. "I will." Merritt made a rush at the irritating Tubby, who leaped provokingly away. But suddenly he gave utterance to a yell of dismay, as in his efforts to retreat he stumbled into the hole which Jose had dug. By this time, to Rob's astonishment, for he had been watching Jose's methods with interest, quite a lot of muddy water had appeared, and into this accumulation of moisture the stout youth fell with a resounding splash. Even the solemn Jose smiled as Tubby sputtered and splashed about in the pool. "Come out of that water," commanded Merritt. "Call this water?" demanded Tubby, sputtering some of it out of his mouth. "Ugh! it tastes more like soap suds to me." "Him alkali," grinned Jose, as Tubby scrambled out and stood, rather crestfallen, on the verge of the magic pool; "mucho malo." "What's 'mucho malo'?" demanded Tubby of Merritt, the self-appointed interpreter. "It means you're a nuisance," retorted Merritt, which reply almost brought on a renewal of hostilities. Rob checked them, however, by reminding the stout youth that the water was for drinking and not for bathing purposes. The boys were anxious to dip their buckets in and return to the wagon, but Jose told them they must wait till the water cleared. "Pretty soon him like glass," he said. Sure enough, after a long interval of waiting, in which there was nothing to do but look at the sand and the burning blue sky above it, the previously muddy seepage water began to take on a green hue. With a yell, the boys rushed forward to dip it up. But as they bent over the brink of the water hole a sudden shout from Jose made them look up. They echoed the Mexican's yell as they did so, for outlined against the sky was a startling figure. It was that of an Indian, his sinewy limbs draped in a blanket of gorgeous hue, and astride of a thin, active-looking calico pony. For an instant the piercing eyes of the red man and the white boys met, and then, with a strange cry, he wheeled his pony and vanished over the rim of the depression. "Was that an Indian?" gasped Tubby, for the figure of the red man had appeared and vanished so swiftly that it seemed almost as if it might have been a delusion. "Moqui, very bad Indian," grunted the Mexican, who seemed nervous and fearful all of a sudden. "Oh, I thought maybe it was a jack-in-the-box," said Tubby, with a cheerful grin, which froze on his face, however, as suddenly as it had come. The rim of the water hole was surrounded by twenty or more wild figures, the companions of the solitary horseman. They had appeared as if by magic. CHAPTER IV.