Sand Canyon, which opens into McElmo Canyon near Battle Rock, has several types of prehistoric ruins, viz, towers, cliff-houses, and large rim-rock pueblos. The tower type of architecture represented by the example here figured (pl. 5, _a_) is isolated from other forms of buildings. This tower is figured by Doctor Prudden, who mentions another in the neighborhood which the author did not visit. TOWERS IN ROAD (WICKYUP) CANYON [Illustration: FIG. 17.—Doorway in Round Tower, McLean Basin.] The nomenclature of the northern canyons of the McElmo has considerably changed in the last 40 years. What we now call the Yellow Jacket was formerly known through its entire course as the Hovenweep. A small canyon opening near its mouth, now known as Road Canyon, was formerly called the Wickyup. The Old Bluff City Road from Dolores, Colorado, to Bluff City, Utah, divides into two branches a short distance before it descends into the McElmo, its left branch passing through Road Canyon, the right bank of which follows the Yellow Jacket, which the traveler fords a short distance above its junction with the McElmo. Wickyup Canyon may be called picturesque, its cliffs being worn into fantastic shapes by water and sand. It has important antiquities, among the most striking of which are two towers (pl. 24, _b_), crowning the tops of low buttes or hills. The walls of these towers are well constructed, one being a simple structure with a single room, the other having appended rectangular rooms extending toward the northwest, some distance along a ridge of rocks. An examination of these two towers, which are about one-quarter of a mile apart, shows that they belong to the same type as the simple forms of those above mentioned, and as the entrance to Square Tower Canyon is not far away, they probably belong to the same series. The first of the towers, called “Bowlder Castle,” is situated a few hundred feet east of the road, from which it is easily seen. This ruin is rectangular in shape and rises from a basal mass of débris indicating broken-down walls of rooms. At a level with the top of this débris on its southern side stands a well-constructed tower with well-made doorway, the threshold and lintel of which are smooth stones, whose edges project slightly from the surface of the wall. One remarkable feature of this tower is that the doorway has been walled up with rude secondary masonry (pl. 25, _a_). The south wall of this building has tumbled over, as is usually the case, but the north wall rises several feet above the base. The masonry of the second tower is also broken down on the south side, but the standing remains of the north wall, which is circular, are over 10 feet high. The indications are that the ground plan of this building was oval in shape and that it inclined inward slightly from foundation to apex. Scattered over the surface are the remnants of fallen walls, and near it there is a well-marked depression, not unlike those found in unit type mounds,