KUNQL. SV, VET. AKADEMIENS HANDLINGAR. BAND 48. N:0 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 iheanus) 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: Orycteropidce (Aard-vark), Oiraffidce (Giraffes)* 

 — — — — Since that time have, however, been described Orycteropus hausanus 

 from Togo, D. erikssoni from Kongo, and 0. leplodon from Cameroon; and further 

 Oiraffa 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. 



