In Africa the evidence of a long period of insulation is somewhat more complex and less easily apparent, but, it seems to me, equally conclusive. We have first, the remarkable fauna of Madagascar, in which lemurs and insectivora predominate, with a few low forms of carnivora; but none of the higher animals, such as apes, antelopes, buffaloes, rhinoceroses, elephants, lions, leopards, and hyænas, which swarm on the continent. The separation of Madagascar from Africa must therefore have occurred before these important groups existed there. Now, we know that all these large animals lived in Europe and Asia during late Miocene times, while lemurs are only known there during the Eocene period, and were probably more abundant in late Mesozoic times. It is almost certain, therefore, that Southern Africa must have been cut off from Europe and Asia during the whole intervening period, or the same development of high forms and extinction of low would have gone on in the one country as in the other. The persistence of a number of low and isolated types in South and West Africa, which are probably a remnant of the ancient fauna of the country, is also favourable to this view. At the time we are considering, therefore, we look upon tropical and South Africa, with Madagascar, as forming a completely isolated land or archipelago; while the Seychelles and Chagos banks, with Bourbon and Mauritius, perhaps, formed another island or group permanently separated from the larger masses. The extra-tropical portion of South Africa was also probably more extensive, affording an area in which its remarkable flora was being developed. Turning to Australia, we should probably find it, at this remote period, more extensive than it is now, including in its area New Guinea and some of the adjacent islands, as well as Tasmania; while another extensive land probably occupied the site of the New Zealand group. It may be considered certain that, whatever elevations and subsidences these countries may have undergone, they have not been connected either with Asia, Africa, or South America during the whole Tertiary period.