262 EAST AFRICAN FLORA AND FAUNA part in 



The same fact is clearly shown by Hart in his careful 

 analysis of the Flora of Sinai. ^ He has published a list of species 

 found in the Dead Sea basin, which are typically tropical in 

 their range. Thus the mallow Abiitilon fniticosum, G. and P., 

 ranges from Senegal through Abyssinia to Beluchistan and 

 Scinde, but is not reported from Egypt. Loranthus acacice, 

 Zucc, is a common parasite on the trees of Nubia, Abyssinia, 

 and the Wadi Arabah. The grass Cyperus eleusinoides, Kunth,, 

 has an enormous range to the south, but misses North-Eastern 

 Africa. Calotropis procera, Willd., is common in Somaliland and 

 the East African Nyika, but its Palestine habitat is separated 

 from these by the whole length of the Red Sea. 



It would be easy to quote further evidence, showing that 

 one of the constituents of the complex fauna of Palestine 

 entered that country from the south, but was excluded from 

 Lower Egypt and North-Eastern Africa. 



As Canon Tristram concludes—" To sum up our deduc- 

 tions, a review of the botany as well as the zoology of the 

 Dead Sea basin reveals to us the interesting fact that we find 

 in this isolated spot, comprising but a very few square miles, a 

 series of forms of life differing decidedly from the species of 

 the surrounding region, to which they never extend, and bearing 

 a strong affinity to the Ethiopian region, with a trace of Indian 

 admixture." ^ As the species which serve as the most striking 

 illustrations of this fact live either in or beside fresh water, a 

 river connection is the most natural agency by which to account 

 for it ; and as these species are absent from the Lower Nile 

 valley and from Egypt, the river connection must have been 

 established along the eastern side of the range of highlands, 

 which separates the Nile from the Red Sea. Thus it is the aim 

 of the present chapter to show that the apparently irreconcil- 

 able contradictions of the facts of plant and animal distribution 

 become intelligible when the former geological evidence is 

 taken into account ; for the recognition of the existence and 

 history of the Rift Valley affords a simple explanation of 

 the occurrence in Palestine of a colony of the inhabitants of 

 Equatorial Africa. 



■• H. C. Hart, Some Account of the Fauna and Flora of Sinai, Petra, and Wady 

 Arabah (London, 1891), pp. 123-172. 



* H. B. Tristram, The Fauna and Flora of Palestine (London, 1884), p. xvi. 



