GEOGRAPHICAL BOTANY. 381 



the whole of Soudan : no more deserts are met with, 

 except where the soil is rocky ; they gradually pass into 

 savannahs (ii, p. 525). The savannahs, during the 

 rainy season, are overgrown with thick grass ; in the other 

 months they resemble a dry stubble-field. The forests 

 consist of Mimosa, and are crowded along the banks of 

 the stream, as in Guiana. Near the rivers the rain dis- 

 trict also extends further north ; hence, at a considerable 

 distance from them, even beyond the 18th degree, the 

 creeks of the desert encroach upon the savannah. 



Throughout the entire district of the Nile, at least as far 

 as the 10th degree south, there are no terrace-like eleva- 

 tions of the soil west of Abyssinia, only immense plains. 

 The terraces of Sennaar, Eazokl, &c., are geographical 

 over-estimates (ii, p. 539). According to Russeger's 

 barometrical measurements, the following places are 

 situated at the annexed altitudes above the Mediterra- 

 nean : Assuan (Syene), 342', Par.; Korosko, 450'; 

 Abuhammed, 963'; El Muchaireff, 1331'; Chartum, 

 1431'; Torra, on the White Nile, 1595; Eleis (13), 

 1667'; and the capital of Kordofan, El Obeehd, 2018'. 

 Russeger found the northern limit to the occurrence of 

 Adansonia, in the savannahs of Kordofan, to exist below 

 14 N. lat. 



On the coast of Adel, on the road from Tajura to the 

 foot of the mountains of South Abyssinia, according to 

 Harris's report of his travels (The Highlands of Ethiopia. 

 London, 1844, vol. i, p. 412), the entire country was 

 desert, and almost dried up in June, i. e. before the com- 

 mencement of the rainy season, and the soil entirely un- 

 cultivated. When the heavy rains commenced it was 

 stormy and unhealthy ; one of the most uninhabitable parts 

 of Africa, The flora was uncommonly poor ; the woody 

 plants consisted of shrubs of Mimosa arid Gadaba Indica, 

 one of the Capparidacese ; subsequently isolated Palms, 

 Cucifera Thebaica, and below 11 N. lat. Phoenix were 

 met with. The only other plants found at the end of the 

 dry season were a few Capparidacese and Malvaceae ; and 



