On page 214 of the "Ancient Monuments of the Mississippi Valley," a group of the flint articles from Clark's Work is represented. The drawing exhibits pretty correctly the irregular outline and general rudeness of these specimens; yet Mr. Stevens states (Flint Chips, p. 440) that "the representations are not at all satisfactory." The only fault, I think, that can be found with these drawings is their small scale, a fault which is very excusable, considering that at the period when Messrs. Squier and Davis published their work, (1848,) flint articles of such shape were no objects of particular attention; for just then the results of the researches of Boucher de Perthes were first laid before the scientific world, which, it is well known, ignored for a long time the significance of the rude flint tools discovered by the indefatigable and enthusiastic French savant in the diluvial gravel-beds of the Somme. It is true, however, that some of the flint discs of Clark's Work are wrought with more care than those represented in the "Ancient Monuments." This fact may be ascribed to a whim of the worker or workers, who gave some of the articles a greater degree of regularity by some additional blows. Mr. Stevens has only seen specimens of this better class, for such were those which Dr. Davis sold to the Blackmore Museum among his collection of Indian relics, and hence the author of "Flint Chips" seems to attribute to them a better general character than they really possess. I learn, however, that Mr. Blackmore, during a recent visit to Ohio, has succeeded in recovering a considerable number of the implements of Clark's Work, and thus an opportunity will be afforded again to investigate the true nature of these relics of a bygone people. The objects in question consist of the compact silicious stone of "Flint Ridge," in Ohio, a locality described on page 214 of the "Ancient Monuments."[6] A careful comparison has established this fact beyond any doubt. The flint or hornstone which occurs in that region, is a beautiful material of a dark color, resembling somewhat the real flint found in nodules in the cretaceous formations of Europe. It is occasionally marked with darker or lighter concentric stripes or bands, the centre of which is formed by a small nucleus of blue chalcedony; and this internal structure appears particularly distinct in specimens which, by exposure, have undergone a superficial change of color. The stone, in general, possesses peculiarities by which it can be recognized at once, even when met in a wrought state far from its original site. According to Mr. Squier, arrow-heads made of this hornstone have been found in Kentucky, Indiana, Illinois, and Michigan. That they occur in Illinois, I can attest from personal experience. [Illustration: Fig. 3.]