Many of the older pueblos of both groups appear to have belonged to the valley types--villages of considerable size, located in open plains or on the slopes of low-lying foothills. A comparison of the plans in Chapters II and III will illustrate these differences. In Tusayan the necessity of defense has driven the builders to inaccessible sites, so that now all the occupied villages of the province are found on mesa summits. The inhabitants of the valley pueblos of Cibola, although compelled at one time to build their houses upon the almost inaccessible summit of Tâaaiyalana mesa, occupied this site only temporarily, and soon established a large valley pueblo, the size and large population of which afforded that defensive efficiency which the Tusayan obtained only by building on mesa promontories. This has resulted in some adherence on the part of the Tusayan to the village plans of their ancestors, while at Zuni the great house clusters, forming the largest pueblo occupied in modern times, show a wide departure from the primitive types. In both provinces the architecture is distinguished from that of other portions of the pueblo region by greater irregularity of plan and by less skillfully executed constructional details; each group, however, happens to contain a notable exception to this general carelessness. In Cibola the pueblo of Kin-tiel, built with a continuous defensive outer wall, occupies architecturally a somewhat anomalous position, notwithstanding its traditional connection with the group, and the Fire House occupies much the same relation in reference to Tusayan. The latter, however, does not break in upon the unity of the group, since the Tusayan, to a much greater extent than the Zuñi, are made up of remnants of various bands of builders. In Cibola, however, some of the Indians state that their ancestors, before reaching Zuñi, built a number of pueblos, whose ruins are distinguished from those illustrated in the present paper by the presence of circular kivas, this form of ceremonial room being, apparently, wholly absent from the Cibolan pueblos here discussed. The people of Cibola and of Tusayan belong to distinct linguistic stocks, but their arts are very closely related, the differences being no greater than would result from the slightly different conditions that have operated within the last few generations. Zuñi, perhaps, came more directly under early Spanish influence than Tusayan.