The rarity of covered passageways in this village is noteworthy, and emphasizes the marked difference in the character of the Tusayan and Zuñi ground plans. The close crowding of rooms in the latter has made a feature of the covered way, which in the scattered plan of Oraibi is rarely called for. When found it does not seem an outgrowth of the same conditions that led to its adoption in Zuñi. A glance at the plans will show how different has been the effect of the immediate environment in the two cases. In Zuñi, built on a very slight knoll in the open plain, the absence of a defensive site has produced unusual development of the defensive features of the architecture, and the result is a remarkably dense clustering of the dwellings. At Tusayan, on the other hand, the largest village of the group does not differ in character from the smallest. Occupation of a defensive site has there, in a measure taken the place of a special defensive arrangement, or close clustering of rooms. Oraibi is laid out quite as openly as any other of the group, and as additions to its size have from time to time been made the builders have, in the absence of the defensive motive for crowding the rows or groups into large clusters, simply followed the usual arrangement. The crowding that brought about the use of the covered way was due in Walpi to restricted site, as nearly all the available summit of its rocky promontory has been covered with buildings. In Zuñi, on the other hand, it was the necessity for defense that led to the close clustering of the dwellings and the consequent employment of the covered way.