KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 48. N:0O 5. 23 
upon the situation of this outlying portion of landscape if it is, or has been acces- 
sible to animals from the subregion where this kind of landscape is the dominating 
type or not. In the former case the faunistic elements of the proper kind wander 
in (or have done so), in the latter it remains uninhabited until some animals from 
the surrounding country have been able to adapt themselves to the life in such a 
landscape. For instance there are tracts of forest in East Africa within SCLATER's 
»Cape subregion», which offer as well from a physical as a biological point of view 
similar conditions of life to mammals as a corresponding portion of forest in the 
West African genuine forest subregion. If such a forest in East Africa has been 
accessible to some West African forest mammals these have, of course, extended 
their distribution to that district, notwithstanding that it lies outside the regular and 
continuous area of distribution for West African forest mammals. Some of the latter 
have also been able to reach further and to occupy more isolated spots than other 
less endowed species." Many examples of such a distribution have become known 
during these last years, and some of them will be mentioned later on. 
If on the contrary a tract of forest in East Africa is and has been so com- 
pletely isolated from the West African forest region that no inhabitants of the latter 
can or could reach the former its fauna must be recruited by members of the sur- 
rounding real East African fauna which then had to adapt themselves to live in this 
forest. Thus a true East African forest fauna can originate. 
It is also evident that some East African forests have such a situation that 
their fauna is partly of West African origin, partly endemic. As will be shown 
further below the forests of Kenia form such a district with a mixed fauna and even 
Kilimanjaro has certain western elements. 
The knowledge about the African fauna has made great progress during the 
last 10—15 years. The relation between the fauna of the West African subregion 
and that of the other subregions has therefore in many respects been found to be 
different and the boundarylines of several genera and species have been drawn up 
quite differently to what was known and done at the time when >»the Geography of 
Mammals> was written. As an instance of this the following mammals may be men- 
tioned. They were at that time believed to be exclusively West African but have 
later been found outside this subregion. A Potto (Perodictius ibeanus) has been 
described by THOMAS from Kakamega Forest near Elgon, British East Africa. The 
genus Nandinia reaches even Kilimanjaro, Uhehe, Nyasa etc. 
On the other hand it was also stated in the work quoted that »the West 
African Region is further characterized by the absence of the following families, well 
represented in other parts of Africa: Orycteropide (Aard-vark), Giraffide (Giraffes)» 
— — — — Since that time have, however, been described Orycteropus hausanus 
from Togo, D. erikssoni from Kongo, and O. leptodon from Cameroon; and further 
Giraffa camelopardalis peralta from Nigeria and &G. c. congoensis from Katanga, Kongo. 
By this are of course not the differences between the West African forest subregion 
! About another possible explanation for the occurrence of certain forest mammals in East Africa conf. 
below. 
