LINKS BETWEEN EAST AND "WEST. 397 



eastwards to 2 8° 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 E. 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 Tragulidas exists in Monbuttu ; and 

 I have also been told of a variety of Lemuridge. The fauna of 

 Central Africa is yet too little 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. Mclo- 

 cichla mentalis, Fras., was till now known only in diametrically 

 opposite places, namely, the Gold and Loango coasts on the one 

 side, and Ukamba in East Africa on the other ; yet it belongs 

 to a family spread over the whole of Central Africa. Macronyx 

 croceus, Vieill., is cited by Heuglin and Antinori as a case of 

 complete isolation in the Bahr-el-Ghazal region, though the 

 birci 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 



