(_a_) Composed of one or two, seldom three, extensive buildings, generally so disposed as to surround an interior court. (_b_) Polygonal pueblos. (_c_) Scattered pueblos, composed of a number of large many-storied houses, disposed in a more or less irregular manner; sometimes in irregular squares or on a line. (_d_) Artificial caves, resembling in number, size, and disposition of the cells the many-storied communal dwelling. (_e_) Many-storied dwellings, with artificial walls, erected inside of natural caves of great size. II. Detached family dwellings, either isolated or in groups forming villages. [Footnote 11: Arch. Inst. of America, 5th Ann. Rept., p. 55; and Arch. Inst. of America, Papers, American series, IV, p. 27.] Many hundreds of ruins have been examined by Mr Bandelier, and doubtless the classification above afforded a convenient working basis for the region with which he is most familiar, the basin of the Rio Grande and its tributaries. It does not apply very well to the western part of the pueblo region. The distinguishing characteristics of the first group (of five classes)--houses several stories high--are as follows: Each building consisted of an agglomeration of a great number of small cells, without any larger halls of particularly striking dimensions. All the buildings, except outhouses or additions, were at least two stories high, and the lower story was entered only from the roof. The various stories receded from the bottom to the top. The prevalence of the estufa (kiva) generally, or often, circular in form. Ruins of class II--detached family dwellings--consist sometimes of a single room; more often of several rooms. The rooms are generally built of stone, although examples constructed of mud and adobe are also found in certain regions. The average size of the room is larger than in the communal building, and there is a gradual increase in size of rooms from north to south. There are front doorways and light and air holes are larger than in the communal houses. Mr Bandolier suggests that the detached family dwelling was the early type, and that only when enemies began to threaten were the communal houses resorted to for purposes of defense. This classification is apparently based on external form alone, without taking into account the numerous influences which modify or produce form; and while no doubt it was sufficient for field use, it is not likely to be permanently adopted; for there does not appear to be any essential or radical difference between the various classes. Moreover, there does not appear to be any place in the scheme for the cliff ruins of the variety especially abundant in De Chelly and found in many other localities, unless indeed such ruins come under class II--detached family dwellings; yet this would imply precedence in time, and the ruins themselves will not permit such an inference.