is always the same. As a matter of fact, the number of ideas expressed by it is often quite varied. We find, for instance, the obtuse triangle with enclosed rectangle (Fig. 4) explained by the Arapaho as the mythic cave from which the buffalo issued, 
Fig. 8b. Side of Arapaho Bag. as cattle-tracks, as a mountain, cloud, brush hut and tent; an acute triangle, with small triangles attached to its base, as a bird-tail, frog, tent and bear-foot.
Nevertheless the explanations given by various tribes show peculiar characteristics in which they differ from those of other tribes. The explanations possess no less a style of their own than the art itself. Triangles are explained as tents by all the tribes, and mountains or hills form a prominent feature of their descriptions; but among the three tribes mentioned only the Sioux see wounds, battle scenes with moving masses of men, horses, the pursuit of enemies, the flight of arrows, in their Conventional de-
