1927] Pilsbry-Bequaert, The Aquatic M ollusks of the Belgian Congo 481 
less recognize so completely the close correlation which exists in Africa 
between climate and vegetation on the one side, and vegetation and 
animal life on the other, that we believe they may be conveniently 
adopted as a basis for a discussion of the distribution of most other 
groups of animals. 
The outstanding feature of Chapin’s map (Map 10) is the recogni- 
tion in the equatorial part of Africa of two main subregions: (1) the 
West AFRICAN SUBREGION, which not only includes West Africa proper, 
viz., Upper and Lower Guinea, as has been generally done, but extends 
inland to cover the greater part of the Belgian Congo and Uganda; 
(2) the East anD SouTH AFRICAN SUBREGION, which also comprises the 
Sudan and Abyssinia and thus encircles completely the West African area. 
GOS 
XK 
EQUATOR 
UZ 0 to 1500 feet 
KY 1500 to 3000 feet 
ee 3000 to 5000 ” 
32 5000 to 10000 » 
jewre] Over 10000 * 
Q 100 200 400 600 800 1000 MILES 
Sa a a ee ON 
Map 11. Orographic map of Africa, prepared under the direction of J. P. Chapin. 
