22 EINAR LONNBERG, MAMMALS COLLECTED BY THE SWEDISH ZOOLOGICAL EXPEDITION ETC. 
uniform climate, and perennial luxuriance of vegetation» — — —; 3:0 the South 
African to which belonged the »extra-tropical» southern portion of the continent. 
The boundary-lines need not to be quoted, they have of course had to be altered, 
because at the time when WALLACE wrote this the knowledge of the interior of Africa 
was, as he points out himself, imperfect. 
The chief interest with this division is that WALLACE on the base of as well 
physical as biological conditions forms the East- and West African subregions, the 
»extra-tropical» has subsequently proved less important. HEILPRIN divided’ also 
>the Ethiopian Realm» in three subregions which he named the »East-Centrai Afri- 
can», the »West African» and the »Saharan». The first of these included also South 
Africa, and the last, the northern desert country, the fauna of which »with almost 
insensible gradations, merges into the fauna of the Mediterranean transition tract». 
LyDEKKER prefers HEILPRIN’s subdivision but adds that Somaliland probably 
ought to be regarded as a separate subregion. 
In a book entitled »The Geography of Mammals» W. L. and P. L. ScuarEr 
in the year 1899 used a zoogegraphical subdivision of the Ethiopian continent which 
is intermediate between Wa Luace’s and HEILPRIN’s systems. They have l:o >the 
West African subregion, including the great equatorial forest of Central Africa con- 
tained in the basins of the western rivers, from the Senegal to the Congo inclusive>; 
2:0 »the Cape subregion including all Africa south of the watershed of the Congo 
on the West and of the Tana on the East coast»; 3:0 »the Saharan subregion, 
consisting (if we exclude the Abyssinian plateau) chiefly of desert, or at any rate 
of a comparalively dry country, including the Sahara, Eastern Africa as far south 
as the Tana river, and Southern Arabia.» 
In this division as well due regard is taken to the physical and biological 
conditions of the three subregions. The characteristic features of the landscape of 
these subregions are just those three original types of African landscape which have 
been mentioned above viz. forest, steppe, and thornbush resp. desert. 
It appears also evident that certain faunistic elements are more or less strictly 
bound to one or the other of these types of landscape. But not all mammals by 
far are so dependent on the environment. Many strong or adaptive mammals may 
occur in two, and some even in all three of these kinds of landscape. Steppe and 
thornbush are, however, more alike than either with the forest, and the faunas of 
the two former have therefore a greater number of elements in common than either 
of them have with the forest. 
The three geographical subregions as defined by the Messrs. ScLATER are, 
however, not homogenous. There are forests outside the »West African subregion», 
there is open country outside the »Cape Subregion», and so on. These outlying 
portions of landscape, otherwise typical to anoter zoogeographical subregion, must, 
however, be taken in possession by some kind of animals to which they offer suitable 
conditions of life (whether this primarily or secondarily is the case). Now it depends 
‘ The Geographical and geological Distribution of Animals. Eded. 1894. 
* Die geograph. Verbreitung u. geolog. Entwickelung der Saugetiere 1897. 
