One of the large rim-rock ruins may be seen on the left bank of Ruin Canyon in full view from the Old Bluff Road. The ruin is an immense pile of stones perched on the very edge of the rim, with no walls standing above the surface. The most striking feature of this ruin is the cliff-house below, the walls and entrance into which are visible from the road (pl. 9, _b_). It is readily accessible and one of the largest in the country. On either side of the Old Bluff Road from Ruin Canyon to the “Aztec Reservoir” small piles of stone mark the sites of many former buildings of the one-house type which can readily be seen, especially in the sagebrush clearings as the road descends to the Picket corral, the reservoirs, and the McElmo Canyon. CANNONBALL RUIN One of the most instructive ruins of the McElmo Canyon region is situated at the head of Cannonball Canyon, a short distance across the mesa north of the McElmo, at a point nearly opposite the store. This ruin is made up of two separate pueblos facing each other, one of which is known as the northern, the other as the southern pueblo (pl. 22, _b_). Both show castellated chambers and towers, one of which is situated at the bottom of the canyon. The southern pueblo was excavated a few years ago by Mr. S. G. Morley, who published an excellent plan and a good description of it, and made several suggestions regarding additions of new rooms to the kivas which are valuable. Its walls were not protected and are rapidly deteriorating. This pueblo, as pointed out by Mr. Morley,[28] has 29 secular rooms arranged with little regularity, and 7 circular kivas, belonging to the vaulted-roofed variety. It is a fine example of a composite pueblo of the pure type, in which there are several large kivas. Morley has pointed out a possible sequence in the addition of the different kivas to a preexisting tower and offers an explanation of the chronological steps by which he thinks the aggregation of rooms was brought about. Occasionally we find inserted in the walls of these houses large artificially worked or uncut flat stones, such as the author has mentioned as existing in the walls of the northwest corner of the court of Far View House. This Cyclopean form of masonry is primitive and may be looked upon as a survival of a ruder and more archaic condition best shown in the Montezuma Mesa ruins farther west, a good example of which was described by Jackson.[29] [28] Amer. Anthrop., n. s. vol. x, no. 4, pp. 596-610, 1908. [29] Op. cit., pp. 428-429. CIRCULAR RUINS WITH PERIPHERAL COMPARTMENTS