The supposed chipped flints are said to appear sparingly in the upper deposits, disappear in the Calcaire de Beauce, and reappear, at first sparingly and then plentifully, in the lacustrian marls below the limestone. They are by far the most numerous in a thin layer of greenish-yellow clay, No. 3 of section, below which they rapidly disappear. There can be no question therefore that if the flints really came from the alleged deposits, and really show the work of human hands, the savages by whom they were chipped must have lived on the shores or sand-banks of this Miocene lake. As regards the geological question, it is right to observe that Professor Prestwich, who visited the section a good many years ago in company with the Abbé Bourgeois, and who is one of the highest authorities on this class of questions, remained unconvinced that the flints shown him really came from the alleged strata below the Calcaire de Beauce, and thought that the specimens which appeared to show human manufacture might have come from the surface, and become intermixed with the natural flints of the lower strata. The geological horizon, however, seems to have been generally accepted by French and Continental geologists, especially by the latest authorities, and the doubts which have been expressed have turned mainly on the proof of human design shown by the implements. This is a question which must be decided by the authority of experts, for it requires special experience to be able to distinguish between accidental fractures and human design, in implements of the extremely rude type of the earlier formations. The test is mainly afforded by the nature of the chipping. If it consists of a number of small chips, all in the same direction, with the result of bringing one face or side into a definite form, adapted for some special use, the inference is strong that the chips were the work of design. The general form might be the result of accident, but fractures from frost or collisions simulating chipping could hardly be all in the same direction, and confined to one part of the stone. The inference is strengthened if the specimen shows bulbs of percussion, where the blows had been struck to fashion the implement, and if the microscope discloses parallel striæ and other signs of use on the chipped edge, such as would be made by scraping bones or skins, while nothing of the sort is seen on the other natural edges, though they may be sharper. But above all, the surest test is afforded by a comparison with other implements of later dates, or even of existing savages, which are beyond all doubts products of human manufacture. Tried by these tests, the evidence stands as follows--