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that once huge wooded area. Later, however, considerable cli- 

 matic changes took place, which most seriously effected the East- 

 and South African suhregion and the forest died out in certain 

 tracts. There arose then the steppe-regions which continued to 

 expand and the huge primeval forest was in this manner cut up 

 as it were, into larger or smaller formless blocks of forest which 

 continued to exist around the great mountains. Here in these 

 forest-islands the animals which had previously had a more uni- 

 form distribution over the whole of Central Africa were now 

 isolated and confined, almost in the same manner as the re- 

 presentatives of land-fauna on islands. And these forest ani- 

 mals — mammals and birds — are thus relicts in forests which 

 are the remains of the once huge continuous, primeval forest, 

 and this division of the forest has given rise to the formation 

 of races analogous to that existing on islands in the ocean. 



This interpretation of Lonnberg of the presence of West- 

 African mammals and birds in East Africa is undoubtedly correct 

 and throws light on many different problems of discontinuity in 

 the Ethiopian fauna. The writer in question confirms his 

 opinion with a number of indisputable proofs, which I have no 

 occasion to repeat in this connection. Reich enow's opinion 

 (Vog. Afr. 1 p. LXXXIX) that the mountains of Atrica were 

 sticking up like islands during a period when the African con- 

 tinent was covered by the sea may, as Lonnberg (op. cit.) 

 points out, also be applied, but in a different manner. 



But Elgon has not only relations with West Africa in 

 respect to the composition of the avi- fauna, but also with 

 South Africa, inasmuch as elements coming from the south 

 have here their northern boundary. Thus, from the eastern 

 slopes of Elgon, in the vicinity of Nai-Swamp, a specimen of 

 Lobivanellus senegallus lateralis, was brought home. P'urther, 

 Irrisor erythrorhynchus niloticus was shot on Elgon, which shows 

 that birds previously only known from North Africa also have 

 their southern boundary in these regions. 



It would be rather a lucky chance if our expedition, during 

 the relatively short time we stayed on Elgon, had procured all 

 the different birds, which really belong to other zoo-geographical 

 sub-regions but, from some cause or other, are nevertheless 

 stationary in the locality. There are surely many others, which 

 future studies of the ornis of the mountain will establish. But 

 already from the few discoveries made one might certainly 

 assume that the bird - kingdom of Elgon includes elements of 

 very different origin, and that the avifauna, here therefore exhi- 

 bits a mixture of forms from many different zoo-geographical 

 regions, and consequently the number of the so-called subtile 

 forms will, of course, be unusually great. 



That Ardeola idae, which is otherwise an inhabitant of 

 Madagascar and South Africa, was shot in the vicinity of Elgon 



