duration, during which the characteristic features of the full-blown Neolithic culture can be shown to have been acquired by slow degrees. Stations, such as caves and rock-shelters, shell-heaps, huts, camps and various sedimentary deposits, yielding relics which prove continuous habitation from Palæolithic to Neolithic times, have been discovered within recent years in many localities throughout Central and Western Europe.
A rambling discussion over such a wide field of research as the transition period is manifestly beyond the limits of this book, but the subject is too important to be altogether ignored. The best way of bringing the gist of the subject before readers is to give a brief account of the arguments derived from one or two characteristic sites.
The late Edward Piette was one of the most strenuous advocates of the existence of a transition period, evidence of which he had obtained in several caves and rock-shelters situated among the rocky regions to the north of the Pyrenees, the most important of which is the cavern of Mas-d'Azil (Ariège). This is a vast subterranean gallery, about 400 metres in length, at the bottom of which foams the turbulent waters of the Arise. During the construction of a road along the stream the relic-bearing deposits, on which M. Piette founds his arguments, were discovered. A résumé of his researches on this site was brought before the Congress of Anthropology and Prehistoric Archæology held in Paris in 1889,
