KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 48. N:0O 5. 25 
and Sahara where the animal life is different, and in some respects more similar to 
that of East Africa, at the same time as endemic forms are to be found there. 
The Somali district is, however, as fully entitled to be regarded as an inde- 
pendent zoogeographical district as South Africa, but both show great affinities with 
East Africa. 
It appears therefore better to accept also for the mammals the same system 
for the zoogeographical subdivision of the Ethiopian continent as REICHENOW has 
used for the birds in his great work »die Vögel Afrikas».! "The author quoted divides 
Africa in a Western forest region and an HEastern Southern steppe region. This 
system is, of course, in the same way as its forerunners based on the biological con- 
ditions which are the results of the topographical, meteorologial and climatological 
factors which have made the forest dominating in one, steppe (and thornbush) in 
another part of the continent. These two main regions are afterwards subdivided 
in a number of smaller zoogeographical provinces and these constitute, so to say, 
smaller zoogeographical centres, or in some cases transition tracts with a mixed fauna. 
There is evidently no sharp boundary lines between these minor provinces, some of 
which will be mentioned below, and not even always or in every respect between the 
main regions. This can the less be the case as the types of landscape and the upon 
the same depending biological conditions are not completely uniform. There are 
thus to be found broad open tracts of land within the forest region, and patches of 
forest scattered in the steppe region with the consequences with regard to the fauna 
which have been set forth above. 
It must also in this connection be remembered that the occurrence of the dif- 
ferent species of mammals in different localities of Africa in the present time is not 
only the result of the present possibilities for distribution to this or that loca- 
lity, but it is in many cases depending upon the possibility to survive which 
the locality in question has been able to offer certain animals. Paleontological facts 
indicate that the ancestors of a great number of the present Ethiopian mammals 
have invaded the continent from the northeast and east during the Miocene and 
Pliocene. It is also wellknown that several mammals which now inhabit Western 
Africa have their nearest relatives in the Oriental region. For instance: 
Perodictius Nycticebus 
Poiana Linsanga 
Nandinia Paradoxurus 
Dorcatherium etc. Tragulus etc. 
The ancestors of the, in present time, West African mammals which invaded 
the continent from the northeast must thus evidently have passed through the coun- 
try which is termed East Africa nowadays, and for some time lived there. Tf such 
mammals still should be represented in East Africa, these representatives may perhaps 
1 Berlin 1900—1901. 
K. Sv. Vet. Akad. Handl. Band 48. N:o 5. 4 
