[The following Essay is reprinted without alteration. It appeared in the _American Antiquarian_ for October, 1881, and has a certain degree of historic value as illustrating the progress of archæologic study in the United States. It is, I believe, the first reasoned argument that the constructors of the mounds of the Ohio Valley were the ancestors of tribes known and resident not remote from the sites of these ancient works. Though this opinion has not yet been fully accepted, the tendency of later studies is unquestionably in its favor.] The question, Who were the Mound-builders? is one that still remains open in American archæology. Among the most recent expressions of opinion I may quote Prof. John T. Short, who thinks that one or two thousand years may have elapsed since they deserted the Ohio valley, and probably eight hundred since they finally retired from the Gulf coast.[46] Mr. J. P. MacLean continues to believe them to have been somehow related to the “Toltecs.”[47] Dr. J. W. Foster, making a tremendous leap, connects them with a tribe “who, in times far remote, flourished in Brazil,” and adds: “a broad chasm is to be spanned before we can link the Mound-builders to the North American Indians. They were essentially different in their form of government, their habits and their daily pursuits. The latter were never known to erect structures which should survive the lapse of a generation.”[48] On the other hand, we have the recent utterance of so able an ethnologist as Major J. W. Powell to the effect that, “With regard to the mounds so widely scattered between the two oceans, it may be said that mound-building tribes were known in the early history of discovery of this continent, and that the vestiges of art discovered do not excel in any respect the arts of the Indian tribes known to history. There is, therefore, no reason for us to search for an extralimital origin through lost tribes for the arts discovered in the mounds of North America.”[49] Between opinions so discrepant the student in archæology may well be at a loss, and it will therefore be worth while to inquire just how far the tribes who inhabited the Mississippi valley and the Atlantic slope at the time of the discovery were accustomed to heap up mounds, excavate trenches, or in other ways leave upon the soil permanent marks of their occupancy.