But this region is not always dry. At certain seasons heavy rainstorms occur, and a veritable deluge descends upon the cracked ground and fills the dry river-beds and _arroyos_ with a turgid flood. In some situations, as, for example, on the river Nazas, a wave of water comes down, covering 10 or 15 feet deep and 500 feet wide in an irresistible flood what a few moments before was a parched and sandy bottom. In the great gullies of the plains similar conditions occur, and woebetide the unfortunate horseman or foot passenger who may be journeying along them at the moment! These sudden freshets are a remarkable feature of the hydrography of the great plateau, and have been more fully described in another chapter. Such a storm we shall have encountered in our expeditions. The rain comes down in torrents, and the lightning flashes and the thunder reverberates among the rocks and canyons; for we have approached a mountain spur, perhaps, in our examination of its mineral resources. The _peon_ in such situations, if there be no shelter at hand, not infrequently, when alone or only with his companions, takes off his clothing and places it in some sheltered rock-crevice, where it keeps dry, until the storm has passed, he himself remaining nude and unconcerned amid the downpour. A mouthful of _mezcal_, or fiery native spirit, will ward off a chill. At night we have sought the hospitality of the owner of some _adobe_ hut. He has done his best for me, but sleeping on the floor is ever trying, and the pack-mule with my baggage and camp-bed has tarried on the road. A rainstorm in this region has the effect of bringing out the noxious vermin from the soil, where they have lain during the heat. Among the most uncomfortable of these are the _alacran_, or scorpion, and the centipede, both of which reptiles are found freely upon the walls and roofs of the _adobe_ dwellings. For my peace of mind we have carefully examined the interior, with a candle, before turning in, and the _mozo_, with a piece of firewood, has smashed the offending centipedes, of which there were a number. Both the scorpion and centipede have a venomous sting, the former sometimes fatal. As to the _peones_, they display small concern at the presence of these vermin. "God willing we shall not be stung," they say, and, rolling themselves in their _ponchos_ on the bare floor in a corner of the habitation, they are soon asleep. But sleep does not visit me so easily. An uncomfortable impression remains, which has not been lessened by the casual remark of the owner of the hut regarding the habits of the scorpions. "Very knowing creatures, senor," he says, as he obsequiously helps to arrange my couch in the middle of the floor--a position chosen by myself--"they have a habit of dropping from the roof on to a person sleeping beneath"!