Are yet other examples needed? At. de Mortillet estimates at more than 25,000 the number of specimens found on the plateau of Saint Acheul, the scene of the earliest discoveries that revealed the existence of man in Quaternary times; and the station of Concise, on Lake Neuchâtel, which is one of the most ancient in Switzerland, yielded a yet more considerable number. Many have, however, been lost or destroyed; the ballast of the railway skirting the lake contains thousands of worked stones and of pieces of the waste left in making them, all of which were taken from the bed of the lake. It must not be forgotten that it is only of late years that the importance of these relics of the past has been recognized and that any one has dreamt of preserving or of studying them. The excavation of a gravel pit at Dundrum (County Down, Ireland) yielded 1,100 flint implements, and M. Belluci himself picked up in the province of Pérouse more than 17,000 pieces, chiefly spear-, lance-, or arrow-heads, belonging to six different types. The Broholm Museum contains 72,409 weapons and implements, all found in Denmark. We can quote similar facts in other countries. Prehistoric stations are numerous in the Sahara and throughout the Wady el Mya, in Algeria, and we have already spoken of the numerous specimens found near Wargla. The workshops in this district are generally surrounded by immense numbers of ostrich eggs, which seem to indicate that that bird was already domesticated.1 In America, Dr. Abbott has sent to the Peabody Museum more than 20,000 stones, which were collected by him at Trenton, on the banks of the Delaware, and quite recently I was told that in sinking a well in Illinois the workmen came upon a deposit of more than 1,000 worked flints, all of oval form. Every one knows the importance of the recent discoveries at Washington, and we might multiply examples _ad infinitum_, for everywhere explorers come upon undoubted traces of the active work and intelligence of comparatively dense populations, all of whom had attained to about the same degree of development. These numerous deposits often mark the, site of regular workshops, tokens of the earliest attempt at social organization. In no other way can we explain the piles of flints in every stage of workmanship lying beside the lumps from which they were detached. One of the most celebrated of these workshops is that of Grand-Pressigny, chief town of the canton of the department of Indre-et-Loire, which is admirably situated between two picturesque rivers, the Claise and the Creuse.