At many places covered by this reconnoissance there were found interesting collections of engraved figures of ancient date cut on bowlders or vertical cliffs. These are generally situated in the neighborhood of ruins, but sometimes exist far from human remains. They generally have geometrical forms, rectangular and spiral predominating. Associated with these occur also representations of human beings, birds, and animals, and figures of bird tracks, human hands, and bear claws. There is a remarkable similarity in all these figures which sometimes occur on the stones composing the masonry of the buildings which indicates they were contemporaneous. They were pecked on the stones with rude stone chisels, but as a rule show no indication of paint. None of these figures could be regarded, without the wildest flights of the imagination, as letters or hieroglyphics, and there is no indication that inscriptions were intended. Their general character, as shown in a cluster (pl. 33), indicates rather clan symbols; in some instances spiral forms were probably made to indicate the presence of water. The incised figures on the walls of buildings were probably decorative in character, the first efforts of primitive man to embellish the walls of his dwellings, an art which reached a very high development in Mexico and Central America. There are, however, indications that these figures were covered with plaster and were therefore invisible, so that we might suppose them to be masons’ signs, indicating the clan kinship of those who constructed the walls. Perhaps the largest group of these pictographs occurs on an eroded bowlder near the mouth of the Yellow Jacket Canyon, just below the great promontory separating it from the McElmo, on the surface of which are the remarkable dwellings composed of slabs of stone set on edge. Another large cluster, the members of which are of the same general style as that already mentioned, was seen in Sandstone Canyon, a few miles south of the road from Dolores to Monticello. There are several groups of pictographs in the neighborhood of the large towers elsewhere described. The most noteworthy of these is situated at the head of the south fork of Square Tower Canyon on a vertical cliff below the ruined Tower No. 4. The face of the cliff is very much eroded, and the figures are in places almost illegible. They consist of bird designs, accompanied with figures of snakes, rain clouds, and other designs, portions of which are obliterated and impossible of determination. As a rule, these pictographs resemble very closely those in the cliff-houses of the Mesa Verde and add their evidence of a uniformity of art design in these two regions.