Iowa, and in the Mexican territory beyond the Rio Grande del Norte. In short, they occupy the entire basin of the Mississippi and its tributaries, as also the fertile plains along the Gulf. Although possessing throughout certain general points of resemblance going to establish a kindred origin, these works, nevertheless, resolve themselves into three grand geographical divisions, which present in many respects striking contrasts, yet so gradually merge into each other that it is impossible to determine where one series terminates and the other begins. In the region bordering upon the upper lakes, to a certain extent in Michigan, Iowa and Missouri, but particularly in Wisconsin, we find a succession of remains, entirely singular in their form and presenting but slight analogy to any others of which we have in any portion of the globe. The larger proportion of these are structures of earth bearing the forms of beasts, birds, reptiles, and even of men; they are frequently of gigantic dimensions, constituting huge _basso-relievos_ upon the face of the country. They are very numerous and in most cases occur in long and apparently dependent ranges. In connection with them are found many conical mounds and occasional short lines of embankment, in rare instances forming enclosures. These animal effigies are mainly confined to Wisconsin, and extend across that territory from Ford du Lac in a south-western direction, ascending the Fox river and following the general course of Rock and Wisconsin rivers to the Mississippi. They may be much more extensively disseminated; but it is here only that they have been observed in considerable numbers. In Michigan, as also in Iowa and Missouri, similar elevations of more or less outline are said to occur. They are represented as dispersed in ranges like the buildings of a modern city, and covering sometimes an arc of many acres. The number of these ancient remains is well calculated to excite surprise, and has been adduced in support of the hypothesis that they are most if not all of them natural formations, "the result of diluvial action," modified perhaps in some instances, but never erected by man. Of course no such suggestion was ever made by individuals who had enjoyed the opportunity of seeing and investigating them. Single structures of earth could not possibly bear more palpable evidences of an artificial origin than do most of the western monuments. The evidences in support of this assertion, derived from the form, structure, position and contents of these remains, sufficiently appear in the pages of this work.