302 INTEEESTING- VEGETATION. ch. xii. 



We halted for luncheon in a convenient spot, and gave 

 some time to botanising on the rocks, where, along with 

 other plants, we found a beautiful variety of the Stachys 

 saxioola of Cosson, densely covered with very long, white, 

 silky hairs. It was near to five o'clock before we were 

 again under way. For some time the defile continued, 

 the cliff-like walls still showing at intervals excavated 

 rock dwellings, and at one point it receives a tributary 

 stream, with a bed now dry, which had cut a similar 

 trench, and whose cliffs also showed the traces of rock 

 dwellings. As we advanced, always ascending, we gradu- 

 ally emerged from the defile, and found ourselves on the 

 slope of the hills that extend northward from the base of 

 the Great Atlas for a distance of thirty or forty miles, and 

 are probably continuous with the low range that we 

 crossed between Shedma and Ain Oumast. There must 

 be some change hereabouts in the mineral composition of 

 the limestone rock, if not in its geological age ; as from 

 about this point the surface was much less barren, and 

 the vegetation more varied. Among other fine CynaraoecB 

 we saw here Atraotylis macrophylla of Desfontaines, only 

 once before met in our journey. 



The sky was overcast, and evening coming on, when we 

 reached the summit-level, which by our observations is 

 3,905 feet (1,190-2 m.) above the sea-level,^ It did not 

 appear to us that the surrounding hills anywhere rise more 

 than 200 or 300 feet aboVe the point where we passed, 

 and, as we afterwards assured ourselves, they gradually 

 diminish in height as they stretch northward from the 

 main range of the Atlas. Although the matter is not 

 free from doubt, we incline to agree with M. Balansa in 

 believing that the hiUs we had now crossed form the 

 watershed between the affluents of the stream running 

 northward by Sheshaoua, and those of the Oued Kseb,' 

 which reaches the sea close to Mogador. Beaudouin's 



> M. Balansa gives for the height in round numbers 1,100 metres, or 

 3,609 English feet. 



