KUNGL. SV. VET. AKADEMIENS HANDUNGAR. HAND 47. \:o 5. 7 



a zoogeographical province, the smaller areas form subdivisions of sueli which differ inter 

 se with regard to their fauna in the same degree as the conditions of life t hat they offer. 



Reichenow has pointed ont in his standard work »Die Vögel Afrikas» that the /Ethi- 

 opian continent south of Sahara can be divided in two main zoogeographical regions viz. 

 the West-Åfrican forest region and the East- and South- African steppe region. 1 Either 

 of these may then be subdivided in a number of smaller provinces. Already from the 

 terms used by the author quoted, it can be concluded that the forming of these two main 

 regions is based on the biological conditions which themselves are due to topographical 

 and climatological factors which have made the forest dominating in one, and the 

 steppe in the other. The easternmost province or subdivision of the West African 

 forest region Reichenow has called the Central African Lake-district, 2 and it extends accor- 

 ding to his definition över the countries round Albert Nyanza, Albert Edward Nyanza, 

 and Lake Kiwu, the districts round Victoria Nyanza with the exception of its southern 

 and southeastern shores, and finally the countries bordering the northern part of Lake 

 Tanganyika. 3 The Eastern-Southern steppe-region is subdivided by Reichenow in no 

 less than eight provinces, three of which may be mentioned here viz. the »Northeastern» 

 district extending southward to Shoa and westward to Lake Tsad; the »Somali-Witu » 

 district southward to »Tana or to Kilimanjaro», and »German East Africa» »from Pan- 

 gani to Rufiji». The author quoted adds, however, that this subdivision is based more 

 on supposition (»Vermutung») than on experience (»Erfahrung»), and »with increasing 

 knowledge essential alterations » are expected. 



At the same time Reichenow points out some irregularities in the distribution of 

 certain birds so that northeastern species in some instances extend further south or the 

 southern further north than could be expected. 



The boundary line between the Somali district and East Africa proper as set forth 

 by Reichenow (conf. above) is naturally enough rather uncertain and conditional. It 

 is at the same time chiefly applicable to the easternmost parts of the countries in question. 

 In the interiör of the continent this boundaryline is not described, but I think that the re- 

 sults of this Expedition will prove its situation in the country north and northeast of Ke- 

 nia as will be explained below. 



In his discussion of the geographical distribution of birds in Africa Reichenow also 

 draws the attention to what appears to be an astonishing fact viz. that the high moun- 

 tains, although distant and situated within different zoogeographical provinces, are in- 

 habited by closely related or similar birds. In this connection he writes as follows: »Aus 

 diesen vereinzelten Vorkomnissen einander so ähnlicher Arten sollte man schliessen, dass 

 in fruherer Zeit ein Zusammenhang zwischen den Hochgebirgen Afrikas bestanden hat. 

 Vielleicht ragten dieselben als Inseln aus dem Ocean hervor, zu einer Zeit, wo das da- 

 zwischen liegende Tiefland noch vom Meere bedeckt war; die Bewohner der Inseln aber 

 blieben in ihrer Verbreitung auf ihre urspriinglichen engeren Wohnplätze beschränkt, 

 auch nachdem das zwischenliegende Land aus dem Meere sich emporgehoben hatte und 



1 »Das westliche Waldgebiet uud das östlich-siidliclie Steppengebiet» 1. c. I, p. LXXXYII. 



2 »Mittelafrikanisches Seengebiet.» 



3 Conf. Reichenow: 



