345 



are common; bragrostis spinosa, Trin, occurs frequently. 

 Besides these the only plants seen were PolUchia six, Car, vlon 

 sp., Salsola Zeyheri, Bth. et. Hook., a Tetragon in, and a dead 

 mesembryanthemum. 



to 



Transition from Sand-dunes to Namib -The sand-dune belt is not 



ot uniform breadth. In its narrowest part it is about 7 miles bro;id 

 from west to east. The eastern limit of the dunes is not indicated 

 by any marked diminution in their height. Tliev arc suddenly 

 replaced by a gentle slope of ripple-marked sand destitute of 

 vegetation and free from pebbles. At the top, the slope, Avhich is 

 perhaps three-quarters of a mile long, merges in a tableland— i he 

 'Namib'— gently rising to the east. To the north is seen a range 

 of enormous sand-dunes and above the horizon to the north-east 

 appear the tops of the Hanoas mountains, 40 miles away beyond 

 the Swakop river. In the nearer distance domes and peaks of 

 granitic and gneissic rock protrude abruptly from the general flat 

 surface which, as far as the eye can see, is without a trace of 

 vegetation. For about 4 miles after leaving the sand-dunes no 

 plants were seen except a small orange-coloured, cni^f;tceous lichen* 

 I urther on three phanerogams appear but for several miles tbey are 

 strictly confined to hollows in the surface which perhaps receive 

 a more copious deposit from the night-fogs than the higher land 

 and in which running water would accumulate on those very rare 

 occasions when rain falls. These, the most characteristic of the 

 Namib plants, are Zygophyllum Stapfii, Schinz ; Aerxa desertorum, 

 Engl.; and the Tetragonia already met with among the sand- 

 dunes. 



The Namib. 



Further east there are many extensive areas on the Namib 

 where the plant population is not more dense than 3 or 4 

 individuals to the acre ; it may be even less. This is nowhere 

 realised more forcibly than towards its eastern boundary along the 

 15 miles separating the railway stations Pforte and Welwitsch. 

 The country here rises very gradually to the east and one passe3 

 mile after mile in the train without seeing a single flowering 

 plant. A few dwarfed specimens of Zygophyllum, -ome dned-up 

 plants of a small Blepharis and a few minute grasses, all confined 

 to the very shallow, dry, sandy channels, composed the entire 

 phanerogamic flora that was visible on both sides of the railway. 

 Acanthosicyos is absent from the Namib proper save here ami 

 there in the sandy river-beds ; in such localities it occurs as tar 

 inland as Haikamchab. 



The Namib is crossed in various directions by numerous wagon- 

 tracks ; that from Walfish Bay to Haikamchab is half a mile or 

 more wide, and is scored by hundreds of wheel-marks. Intormer 

 times this was the main-road from the coast to the hinterland, but 

 since the construction of the German railway it has been .almost 

 deserted. Many of the wheel-impressions seen to-day m us ; there- 

 fore be of considerable age. Galtonalso records that fc ™PW»aoM 

 made on this crisp gravelly soil take years to « fe ? * th *> *fV° 

 ke almost stereotyped." Their persistence must be due to the 



