The absence of a criterion to distinguish between races and sub-races, and our ethnological ignorance generally, makes it impossible to offer more than a very off-hand estimate of the average variety of races in the different countries of the world. I have, however, endeavoured to form one, which I give with much hesitation, knowing how very little it is worth. I registered the usually recognised races inhabiting each of upwards of twenty countries, and who at the same time formed at least half per cent of the population. It was, I am perfectly aware, a very rough proceeding, so rough that for the United Kingdom I ignored the prehistoric types and accepted only the three headings of British, Low Dutch, and Norman-French. Again, as regards India I registered as follows:--Forest tribes (numerous), Dravidian (three principal divisions), Early Arian, Tartar (numerous, including Afghans), Arab, and lastly European, on account of their political importance, notwithstanding the fewness of their numbers. Proceeding in this off-hand way, and after considering the results, the broad conclusion to which I arrived was that on the average at least three different recognised races were to be found in every moderately-sized district on the earth's surface. The materials were far too scanty to enable any idea to be formed of the rate of change in the relative numbers of the constituent races in each country, and still less to estimate the secular changes of type in those races. It may be well to take one or two examples of intermixture. Spain was occupied in the earliest historic times by at least two races, of whom we know very little; it was afterwards colonised here and there by Phoenicians in its southern ports, and by Greeks in its eastern. In the third century B.C. it was invaded by the Carthaginians, who conquered and held a large part of it, but were afterwards supplanted by the Romans, who ruled it more or less completely for 700 years. It was invaded in the fifth century A.D. by a succession of German tribes, and was finally completely overrun by the Visigoths, who ruled it for more than 200 years. Then came the invasion of the Moors, who rapidly conquered the whole of the Peninsula up to the mountains of Asturias, where the Goths still held their own, and whence they issued from time to time and ultimately recovered the country. The present population consists of the remnants of one or more tribes of ancient Iberians, of the still more ancient Basques, and of relics of all the invaders who have just been named. There is, besides, a notable proportion of Gypsies and not a few Jews.