LINKS BETWEEN EAST AND WEST. 397 eastwards to 28° 50’ E. long. But I do not doubt that, as regards its eastern limit, a much greater extension may be revealed by further investigations, for in former journeys I have found even at 31° H. long. forms of vegetation which decidedly belonged to the western tropics. If, then, such an advance towards the east should be confirmed, of which I have no doubt, a connexion will thus be formed with hitherto apparently isolated representatives of the same species in the west. It seems to me more than probable, from instances I have seen, that a representative of the Tragulidee exists in Monbuttu ; and I have also been told of a variety of Lemuride. The fauna of Central Africa is yet too httle known to be applied to the elucidation of disputed points, but it seems as if the soil of the. Black Continent is able to furnish reasons for all apparent exceptions, and connecting-links for all broken chains. Not long ago Anomalurus, the West African representative of the flying squirrel, was a completely isolated phenomenon, until Peters described the Anomalurus orientalis of Zanzibar from Hildebrand’s specimens. Now, I have found a new species of the same kind in Monbuttu, whereby the chain is completed from one side of the continent to the other. The northern limit of this interesting variety may extend in the western division of our territory to about 4° N. lat., but then it turns in a long curve to the south-south-east, following the boundaries of the true forest region.

What has been affirmed with regard to certain Mammalia is of course true of other classes of animals, and especially of birds. Whenever the same species has appeared isolated in the west and east, the north and south, we are quite justified in searching for their connecting links in our territory. J/elocwchla mentalis, Fras., was till now known only in diametrically opposite places, namely, the Gold and Loango coasts on the one side, and Ukamba in Hast Africa on the other; yet it belongs to a family spread over the whole of Central Africa. acronyz croceus, Vieill., is cited by Heuglin and Antinori as a case of complete isolation in the Bahr-el-Ghazal region, though the bird is commonly seen southwards from 6° N. lat. It would therefore be by no means strange if continued collecting rendered the isolation of Pitta angolensis doubtful by the discovery of