DERIVATION OF THE FAUNA 29 



ent of other barriers. The zones occur in East Africa as 

 broad bands of territory extending parallel to the coast, 

 owing to the uniformity with which the land rises as we 

 proceed inland to the high central plateaux. Within each 

 zone the altitudinal and climatic conditions and plant species 

 are fairly uniform. The zones, owing to the irregular dis- 

 tribution of the flora, can be further subdivided into plant 

 associations such as grassy plains, thornbush thickets, or 

 dense forests. By using the zonal names in connection 

 with the plant associations, we are enabled to define very 

 precisely the habitats of the various animals inhabiting 

 the region. The zones are primarily upon a floral basis, 

 being founded upon the ranges of various trees and shrubs 

 to which the distribution of a majority of the animals con- 

 form. The zones with the plant species peculiar to them 

 are described at length in the chapter concerning the flora. 

 The whole region under consideration falls naturally 

 into five life-zones. Beginning at the coast, we find a nar- 

 row belt of lowland varying in width from five to twenty 

 miles and extending from the Lamu Islands southward. 

 This tropical belt is marked florally by the occurrence of 

 the cocoa-palm, and climatically by the greater amount of 

 moisture it receives in comparison to the desert which suc- 

 ceeds it. Peculiar to the tropical coast zone are the sable, 

 Egocerus niger roosevelti, the suni, Nesotragus moschatus de- 

 serticoluy the blue duiker, Cephalophus monticola hecki, and the 

 maritime oribi, Ourebia montana haggardi. The sable extends 

 no farther north than Mombasa, but the other species of ante- 

 lope extend to the northern limits of the zone near Lamu. The 

 sable and the oribi are more characteristic of the parklike 

 country bordering the groves of cocoa-palms than of the 



