28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I47 



Both the diagonal door, leading cornerwise from one room to an- 

 other, and the Tau-shaped door appear to be Late Bonitian intro- 

 ductions. Of the former (pi. 15, left) we know of only seven or 

 eight, all in houses of fourth-type masonry; of Tau-shaped doors, 

 32 in number, all but two are found in Late Bonitian walls. 



Architecturally, the diagonal doorway seems such an admirable 

 idea one would expect to find it in general use and from an early date. 

 But quite the contrary. Relying upon memory rather than a fresh 

 search of the literature, I recall only one example from another Chaco 

 ruin and none at all among ancient cliff-dwellings. W. H. Jackson 

 (1878, p. 436) described a diagonal door in a second-story wall at 

 the northwest corner of Pueblo Pintado, but, surprisingly, he reported 

 none at Pueblo Bonito although those connecting Rooms 173B and 

 228B, 180B and 242B, must have been visible to him in 1877 as they 

 were to Mindeleff 10 years later. The feature appears occasionally 

 in P. Ill ruins north of Chaco Canyon but only occasionally. 



The T- or Tau-shaped door is an enigma. It is widely distributed 

 throughout the Southwest both in historic and prehistoric villages, 

 but no one to my knowledge has yet advanced a convincing explana- 

 tion of its form or purpose. I have seen T-doors in prehistoric ruins 

 as far west as Navaho Mountain but in none earlier than P. III. 

 At Pueblo Bonito T-shaped doors were peculiar to the Late Boni- 

 tians since only two examples are known in Old Bonitian houses, and 

 one of these, that connecting Rooms 321 and 323, is so conspicuously 

 framed in third-type stonework as to evidence Late Bonitian altera- 

 tions. Without regard to masonry, 23 of our 32 T-shaped doors occur 

 in ground floor rooms, eight in those of the second story, and one in 

 the third story, between Rooms 174C and 175C. This latter and 

 those in the west walls of 226 and 227 were interior doorways ; all 

 others faced upon one of the courts. Largest of all, 7 feet 4 inches 

 high and a foot above the floor, opened through the east wall of 

 Room 334 upon the roof of Kiva T (pi. 16, left). 



Two miniature T-shaped recesses, both empty, occur in the south 

 wall of Old Bonitian Room 326B (pi. 11, left) which stands 8 feet 

 4 inches above its floor level with no trace of ceiling poles. Rarely 

 does an Old Bonitian house boast a third story. 



Ventilators are seen in rooms of all four masonry types. Altogether 

 we have record of 183 of which 28 appear in 10 Old Bonitian rooms ; 

 11 in six houses of second-type construction ; 33 in 19 third-type struc- 

 tures, and the remainder in 53 fourth-type rooms six of which are in 

 the third story. Ventilators vary in their dimensions and in height 



