FAUX A OF EAST AFRICA. 9 



there is an enormous gap, for Ave do not find it again until we 

 -come to the Uasingishu Plateau, which is aljout 6000 ft. above 

 sea-level. This is an unexplicahle hiatus. I have not, however, 

 had an opportunity of comparing Uasingishu skins with speci- 

 mens from the coast, so cannot testify to their absolute identity.'* 



5, Waller's Gazelle.- — This species is another example of 

 intermittent distribution. It is found on the steppes on the east 

 or left bank of the Tana River below Hameye and extends 

 northwards to Somaliland. Then there is a great gap, for no 

 trace of it is seen until we reach the neighbourhood of Lake 

 Magadi, a distance of 200 miles ; a few are also found on the 

 •Berengeti Plains, principally to the north of the Voi-Taveta 

 Railway line. It is also believed to exist in Usambara district in 

 Tanganyika Territory, but this is its southerly limit. 



6. Hartebeest. — The common hartebeest of the country is 

 Coke's, and, as a rule, wdienever a square mile or two of open 

 ■country occurs we get this uljiquitous beast. It is locally called 

 the " Kongoni." A curious thing happens in the Rift Talley ; at 

 the south end of the Rift Valley in Kenj^a Colony all the harte- 

 beest are cokei, but about the north end of Naivasha Lake 

 nearly every hartebeest seen belongs to the ^Neumann's variety, 

 and as we go farther north and west we find this gives wa}^ to the 

 curious Jackson's variety, and on the Uasingishu Plateau there 

 is no species of the hartebeest other than Jackson's. This, of 

 ■course, is not so much a question of the distribution of one species 

 as a change of one species, and the variations of the Grant's 

 ■Gazelle and the Oryx in diSerent areas could similarly be traced. 



These facts of erratic distribution are difficult to undei'stand, 

 ftnd to find an adequate explanation I am inclined to believe that 

 w^e shall have to go back to the time when the progressive desic- 

 •cation of this portion of Africa set in. 



This question of desiccation cannot be discussed here at any 

 length. I have collected a considerable amount of evidence re- 

 garding it which was published in the ' Geographical Journal,' 

 November 1914. The causes are by no means clear, buf certain 

 meteorologists have advanced the opinion that during the glacial 

 period of Europe there was a much greater rainfall in the areas 

 to which the glaciers did not extend. At any rate, there is clear 

 ■evidence that in Pleistocene times or thereabouts the glaciers of 

 Kenya extended some 5000 ft. below their present terminations, . 

 viz., to about 9000 ft. above sea-level, and on Ruwenzori glacial 

 deposits are, it is stated, to be found at the surprisingly low alti- 

 tude of 5000 ft. above sea-level. 



Now the greater rainfall during that period, Avhicli only de- 

 creased gradually through a long term of years, must have resulted 

 in a marvellous expansion of the forest area ; the high-level flora 



* The topi is also common on tlie Loita Plains and southwards on the same 

 meridian of Longitude into Tiinganj'ika Territory. 



