There are certain problems which particularly require to be examined. With respect to the antiquity of the stone buildings and pyramids, it would be difficult to attempt to do more than endeavour to form reasonable deductions from the evidence afforded by the state of those ruins, and the information given about them by the Indians at the time of the conquest. The conquerors, after they had settled in Yucatan and Guatemala, were accompanied by Spanish missionaries of great ability. We possess in the writings of Bishop Las Casas and Bishop Landa works of the greatest value, for both those prelates when they were engaged in their duties of converting the natives, were acquainted with the language of the tribes amongst whom they worked. In the prosecution of researches into subjects which relate to Central America, it is desirable as a preliminary step to consider the comparative civilisation of the Indians, as far as that is brought into evidence by what has been discovered with respect to mounds and earthworks, not only in that region, but also throughout the valley of the Mississippi. A distinction must also be made between earthworks which are unquestionably of great antiquity, and those that possibly may have been raised since the date of the arrival of European settlers. Therefore the geometrically planned inclosures in Ohio should be excluded from this inquiry. It is otherwise with great ramparts such as those inclosing Fort Ancient on the steep promontory in the valley of the Little Miami, which are of special importance on account of the parallelisms with the similar fortifications made by the Quichés and Kachiquels in Guatemala. There are exceptional circumstances connected with the mounds in North America. It has to be remembered that they were not always burial places. When De Soto arrived with his fleet in Florida, the chief cacique of the tribe dwelling near the landing place, was living on the top of a mound about fifty feet high. This mound was pointed out to me when I was at Tampa. It appeared to be made for the purpose of placing huts upon its summit. The platform was sufficiently large to give room for several dwellings. There are also mounds near the western bank of the Mississippi, between Natchez and the mouth of the Arkansas. One of them resembled that at Tampa, and had a wide level space on the summit.