wall, and the immense arched roof of solid stone projects forward fifteen or twenty feet beyond the house (see section, figure 3). At the right the ledge ceases, and at the left stops short against a massive vertical wall. The niche-stairway affords the only possible means of approach. “The house occupies the entire floor of the niche, which is about one hundred and twenty feet long by ten in depth at the deepest part. The front wall to the right and left of the doorway is quite low, portions having doubtless fallen off. The higher wall _f g_ is about thirty feet long, and from ten to twelve feet high, while a very low rude wall extends along the more inaccessible part of the ledge, and terminates at the extreme right in a small enclosure, as seen in the plan at _c_. “In the first apartment entered, there were evidences of fire, the walls and ceiling being blackened with smoke. In the second, a member of the party, by digging in the rubbish, obtained a quantity of beans, and in the third a number of grains of corn; hence the names given. There are two small windows in the front wall, and doorways communicate between rooms separated by high partitions. “The walls of these houses are built in the usual manner, and average about a foot in thickness. “The upper house seems to be in a rather unfinished state, looking as if stone and mortar had run short. And when one considers that these materials must have been brought from far below by means of ropes, or carried in small quantities up the dangerous stairway, the only wonder is that it was ever brought to its present degree of finish.” [Illustration: Triple-Walled Tower on the McElmo.] The ruins of a triple-walled tower with fourteen sectional apartments between the outer and second walls were examined near the McElmo. One of these sectional apartments was still standing to the height of twelve feet. We have already referred to the group of ruins at Aztec Springs near the divide between the McElmo and the lower Mancos tributaries. “These ruins,” says Mr. Holmes, “form the most imposing pile of masonry yet found in Colorado. The whole group covers an area of about four hundred and eighty thousand square feet, and has an average depth of from three to four feet.” The accompanying plan, with the measurements and dimensions indicated upon it, precludes the necessity of a detailed description. [Illustration: RUINS at AZTEC SPRING SOUTH WEST COLORADO _W. H. Holmes_] The walls are twenty-six inches thick, and in some cases are built double. The whole resembles in plan one of the ruined pueblos of the Chaco, with the addition that it was designed to be an impregnable fortress.