The subterranean kiva of the Shumopavi group, above illustrated, is exceptional as occurring at some distance from the mesa rim. Probably all such exceptions to the rule are located in natural fissures or crevices of the sandstone, or where there was some unusual facility for the excavation of the site to the required depth. The most noteworthy example of such inner kiva being located with reference to favorable rock fissures has been already described in discussing the ground plan of Walpi and its southern court-inclosed kiva (p. 65). _Masonry._--The exterior masonry of these chambers seems in all cases to be of ruder construction than that of the dwelling houses. This is particularly noticeable in the kivas of Walpi on the mesa edge, but is apparent even in some of the Zuñi examples. One of the kivas of house No. 1 in Zuñi, near the churchyard, has small openings in its wall that are rudely framed with stone slabs set in a stone wall of exceptional roughness. Apparently there has never been any attempt to smooth or reduce this wall to a finished surface with the usual coating of adobe mud. [Illustration: Plate LIII. Site of K’iakima, at base of Tâaaiyalana.] In Tusayan also some of the kiva walls look as though they had been built of the first material that came to hand, piled up nearly dry, and with no attempt at the chinking of joints, that imparts some degree of finish to the dwelling-house masonry. The inside of these kivas, however, is usually plastered smoothly, but the interior plastering is applied on a base of masonry even in the case of the kivas that are wholly subterranean. It seems to be the Tusayan practice to line all sides of the kivas with stone masonry, regardless of the completeness and fitness of the natural cavity. It is impossible, therefore, to ascertain from the interior of a kiva how much of the work of excavation is artificial and how much has been done by nature. The lining of masonry probably holds the plastering of adobe mud much better than the naked surface of the rock, but the Tusayan builders would hardly resort to so laborious a device to gain this small advantage. The explanation of this apparent waste of labor lies in the fact that kivas had been built of masonry from time immemorial, and that the changed conditions of the present Tusayan environment have not exerted their influence for a sufficient length of time to overcome the traditional practice. As will be seen later, the building of a kiva is accompanied by certain rites and ceremonies based on the use of masonry walls, additional testimony of the comparatively recent date of the present subterranean types.