Can any date be assigned to this period of semi-civilisation which, instead of improving more and more like civilisation in Europe, became suddenly eclipsed, owing to causes which are unknown to us? This question must be answered in the negative, if we are called upon to fix any settled and definite date. Nevertheless, the conclusion to which American archæologists have arrived is, that the history of the New World must be divided into four definite periods. The first period includes the rise of agriculture and industrial skill; the second, the construction of mounds and inclosures; the third, the formation of the "garden beds." In the last period, the American nation again relapsed into savage life and to the free occupation of the spots which had been devoted to agriculture. In his work on 'Pre-historic Times' Sir John Lubbock, who has furnished us with most of these details, estimates that this course of events would not necessarily have required a duration of time of more than 3000 years, although he confesses that this figure might be much more considerable. But Dr. Douler, another _savant_, regards this subject in a very different way. Near New Orleans he discovered a human skeleton and the remains of a fire, to which, basing his calculations on more or less admissible _data_, he attributes an antiquity of 500 centuries! Young America would thus be very ancient indeed! By this instance we may see how much uncertainty surrounds the history of primitive man in America; and it may be readily understood why we have thought it necessary to adhere closely to scientific ideas and to limit ourselves to those facts which are peculiar to Europe. To apply to the whole world the results which have been verified in Europe is a much surer course of procedure than describing local and imperfectly studied phenomena, which, in their interpretation, lead to differences in the estimate of time, such as that between 3000 and 50,000 years! CONCLUSION. Before bringing our work to a close we may be permitted to retrace the path we have trod, and to embrace in one rapid glance the immense space we have traversed.