Sometimes these Indians built their houses on the ledges of steep rocks, or canyons. Such houses were called cliff dwellings, and many remains of these queer homes are still found in the southwestern part of our country. The Indians who lived there were gentle, and not fond of fighting, but they built fortresses and cliff dwellings to defend themselves when attacked by the savage Indians. You see, the savage Indians did not grow any grain or vegetables, but they came down from the north to steal the provisions of the southern Indians. These, therefore, carried all their supplies into the cliff houses, which they built in such a way that it was almost impossible for an enemy to get in them. The inhabitants themselves, however, easily went in and out by means of ladders, which led from story to story, or from ledge to ledge. Their houses had no doors down near the floor, but were entered by a hole in the roof. In each of these fortresses there was a great cistern, full of water, and so large a supply of food that the Indians could stand a long siege. In times of danger they pulled all their ladders away up out of reach, and when their enemies tried to climb the steep cliffs or straight walls, they pelted them with stones and arrows, and thus drove them away. Wise men tell us that even before our country was occupied by the savage, barbarous, and half-civilized Indians, whose way of living has just been described, it had been inhabited by their ancestors or by an older race of men. We know they existed, because people have dug up their bones. These have been found principally inside huge earthen mounds of very queer shapes. The mounds were evidently built by those early inhabitants, who are hence known as the mound builders. Trees hundreds of years old now grow upon these mounds, which are found in most parts of the eastern Mis-sis-sip´pi valley, especially in O-hi´o. In one place you can see a big mound representing a snake one thousand feet long, his body lying in graceful curves along the ground. This snake's mouth is wide open, and he looks as if trying to swallow an egg-shaped mound, which is one hundred and sixty-four feet long, and hence a pretty big mouthful. As this mound is so odd, it has been inclosed in a park, where it is to be kept just as it is, to remind people of the mound builders who lived here so long ago. [Illustration: mound in shape of snake.]