The class of ruins which has been designated as the remains of villages located for defense comprises all the most striking remains in the canyon, many of which may properly be termed cliff ruins. The characteristics of the class are: A site more or less difficult of access--generally an elaborate ground plan, although sometimes they consist of only a few rooms--and the invariable presence of the kiva or estufa, here always circular in form. The largest ruin of this class occurs in Del Muerto, and is known as Mummy Cave ruin. It is called by the Navajo Tse-i-ya-kin. It is situated in the upper part of the canyon, near the junction of a small branch, and has an extensive outlook. At a height of about 80 feet above the top of a gentle slope of earth and loose rock, and perhaps 300 feet above the stream bed, there are two coves in the rock, connected by a narrow bench. The western cove is about 100 feet across and its back is perhaps 75 feet from the front wall of the cliff. The eastern cove is over 200 feet across and perhaps 100 feet deep, while the connecting ledge is about 110 feet long. Ruins occur on the central ledge and on similar ledges in the back parts of both coves. The western or smaller cove is accessible only from the ledge, which in turn can be approached only from the eastern cove. The smaller cove had a row of little rooms across the back and there are traces of walls on the slope in front of these. Fourteen rooms can now be made out on the ground; altogether there may have been 20 rooms in this portion. Practically all the available space on the ledge was occupied by rooms, and 10, all of considerable size, can now be traced. The total number in this portion was 14 or 15. The eastern cove contained the largest part of the settlement. The back part is occupied by a ledge about 50 feet wide entirely covered by remains of walls. Some 44 rooms can now be made out on the ground, in addition to 3 or perhaps 4 circular kivas, and the whole number of rooms may have been 55. Assuming, then, that the various portions of the ruin were inhabited at the same time, we would have a total of 90 rooms; but, as many of them could be used only for storage, the population could not have been more than 60 persons. The rooms in the western cove are fairly uniform in size and were probably habitations, for they are all too large to be classed as storage rooms. There was no kiva in this portion, however, nor any unoccupied place where a kiva might have been placed. It seems clear, therefore, that this portion was either an appendage of the other or was occupied at a later period; in either case it was constructed at a date subsequent to the remains in the eastern cove. [Illustration: Plate XLVIII Mummy Cave, Central and Eastern Part]