Metz, who found a true palaeolith of black flint at Madisonville, in the Little Miami valley, eight feet below the surface. Since then further discoveries have been made in the same neighbourhood by Dr. Metz, and in Jackson county, Indiana, by Mr. H. T. Cresson; and the existence of man in that part of America toward the close of the Glacial period may be regarded as definitely established. The discoveries of Miss Babbitt and Professor Winchell, in Minnesota, carry the conclusion still farther, and add to the probability of the existence of a human population all the way from the Atlantic coast to the upper Mississippi valley at that remote antiquity. [Footnote 8: Wright's _Ice Age in North America_, p. 516.] [Sidenote: and in Delaware.] A still more remarkable discovery was made by Mr. Cresson in July, 1887, at Claymont, in the north of Delaware. In a deep cut of the Baltimore and Ohio Railroad, in a stratum of Philadelphia red gravel and brick clay, Mr. Cresson obtained an unquestionable palaeolith, and a few months afterward his diligent search was rewarded with another.[9] This formation dates from far back in the Glacial period. If we accept Dr. Croll's method of reckoning, we can hardly assign to it an antiquity less than 150,000 years. [Footnote 9: The chipped implements discovered by Messrs. Abbott, Metz, and Cresson, and by Miss Babbitt, are all on exhibition at the Peabody Museum in Cambridge, whither it is necessary to go if one would get a comprehensive view of the relics of interglacial man in North America. The collection of implements made by Dr. Abbott includes much more than the palaeoliths already referred to. It is one of the most important collections in the world, and is worth a long journey to see. Containing more than 20,000 implements, all found within a very limited area in New Jersey, "as now arranged, the collection exhibits at one and the same time the sequence of peoples and phases of development in the valley of the Delaware, from palaeolithic man, through the intermediate period, to the recent Indians, and the relative numerical proportion of the many forms of their implements, each in its time.... It is doubtful whether any similar collection exists from which a student can gather so much information at sight as in this, where the natural pebbles from the gravel begin the series, and the beautifully chipped points of chert, jasper, and quartz terminate it in one direction, and the polished celts and grooved stone axes in the other." There are three principal groups,--first, the interglacial palaeoliths, secondly, the argillite points and flakes, and thirdly, the arrow-heads, knives, mortars and pestles, axes and hoes, ornamental stones, etc., of Indians of the recent period. Dr.