In the first place, we have the _sepulchral mounds_ or _tumuli_, the numbers of which may be reckoned by tens of thousands. They vary in height from 6 feet to 80 feet, and are generally of a circular form; being found either separately or in groups. Most frequently only one skeleton is found in them, either reduced almost to ashes, or--which is more rare--in its ordinary condition, and in a crouching posture. By the side of the corpse are deposited trinkets, and, in a few cases, weapons. A practice the very contrary to this now obtains in America; and from this we may conclude that a profound modification of their ideas has taken place among the Indians since the pre-historic epochs. It is now almost a certain fact that some of the small _tumuli_ are nothing but the remains of mud-huts, especially as they do not contain either ashes or bones. Others, on the contrary, and some of the largest, contain a quantity of bones; the latter must be allied with the _ossuaries_ or bone-pits, some of which contain the remains of several thousand individuals. It would be difficult to explain the existence of accumulations of this kind if we did not know from the accounts of ancient authors that the Indians were in the habit of assembling every eight or ten years in some appointed spot to inter all together in one mass the bones of their dead friends, which had been previously exhumed. This singular ceremony was called "the feast of the dead." We shall not say much here as to the _sacrificial mounds_, because no very precise agreement has yet been arrived at as to their exact signification. Their chief characteristics are, that, in the first place, they are nearly always found within certain sacred enclosures of which we shall have more to say further on, and also that they cover a sort of altar placed on the surface of the ground, and made of stone or baked clay. In the opinion of certain archæologists, this supposed altar is nothing but the site of a former fire-hearth, and the mound itself a habitation converted into a tomb after the death of its proprietor. It will therefore be best to reserve our judgment as to the existence of the human sacrifices of which these places might have been the scene, until we obtain some more complete knowledge of the matter. The _Temple-Mounds_ are hillocks in the shape of a truncated pyramid, with paths or steps leading to the summit, and sometimes with terraces at different heights. They invariably terminate in a platform of varying extent, but sometimes reaching very considerable dimensions. That of Cahokia, in Illinois, is about 100 feet in height, and at the base is 700 feet long and 500 feet wide. There is no doubt that these mounds were not exclusively used as temples, and, adopting as our authority several instances taken from Indian history, we may be permitted to think that on this upper terrace they were in the habit of building the dwelling of their chief.