Their constructions were similar in design and arrangement to those found in Mexico and Central America. Like the Mexicans and Central Americans, they had many of the smaller structures known as _teocallis_, and also large high mounds, with level summits, reached by great flights of steps. Pyramidal platforms or foundations for important edifices appear in both regions, and are very much alike. In Central America important edifices were built of hewn stone, and can still be examined in their ruins. The Mound-Builders, like some of the ancient people of Mexico and Yucatan, used wood, sun-dried brick, or some other material that could not resist decay. There is evidence that they used timber for building purposes. In one of the mounds opened in the Ohio Valley two chambers were found with remains of the timber of which the walls were made, and with arched ceilings precisely like those in Central America, even to the overlapping stones. Chambers have been found in some of the Central American and Mexican mounds, but there hewn stones were used for the walls. In both regions the elevated and terraced foundations remain, and can be compared. I have already called attention to the close resemblance between them, but the fact is so important in any endeavor to explain the Mound-Builders that I must bring it to view here. Consider, then, that elevated and terraced foundations for important buildings are peculiar to the ancient Mexicans and Central Americans; that this method of construction, which, with them, was the rule, is found nowhere else, save that terraced elevations, carefully constructed, and precisely like theirs in form and appearance, occupy a chief place among the remaining works of the Mound-Builders. The use made of these foundations at Palenque, Uxmal, and Chichen-Itza, shows the purpose for which they were constructed in the Mississippi Valley. The resemblance is not due to chance. The explanation appears to me very manifest. This method of construction was brought to the Mississippi Valley from Mexico and Central America, the ancient inhabitants of that region and the Mound-Builders being the same people in race, and also in civilization, when it was brought here.