NATIVE TRIBES. 45 STRUCTURE OF “ TIPIS” AND SEMI-SUBTERRANEAN WINTER HOUSES. As is everywhere the case with all these peoples their “ tipis”’ differed in detail ; but essentially they consisted of a conical framework of poles covered with birch- bark or rush mats, fir boughs, elk or caribou hides (see Plate III.). Three or PLATE XII. Courtesy of American Museum of Natural History, New York, U.S.A. Details of the structure of an Interior Salish semi-subterranean house. four poles were first set up and lashed together at one end to form a large tripod: other poles were spaced evenly between them resting against the forked apex, and the narrow entrance was closed with a flap. The fire was central. Among the