— 131 — 



the smallness of the bushes and the poor development of 

 Aristida. The occurence of an Allium sp. (with ripe fruits) 

 is likewise indicative of such a soil. 



In a depression with the soil hard and crackling with 

 salt and the subsoil moist, we have a Salt-desert flora con- 

 sisting of Halocnemum sirobilaceum and Aeluropus littoralis, — 

 here the ground-water is still nearer the surface. The stony 

 soil is more sterile than either the sand or the salt; the plant 

 characteristic for this soil is Reaumuria fruticosa, a shrub 

 half a metre high, with thick stiff branches densely clothed 

 with very small thick leaves crusted with grains of salt. 

 A few Tamarix hispida and Salsola Arbuscula occur here as 

 stunted bushes with wide bare spaces between them. On 

 loose stones I gathered the following lichens : Sarcogyne peri- 

 leuca Wain., Placodium Paulsenii Wain., Acarospora interrupta 

 (Ehbg.). 



8. Desert at Kara Aigir on the left bank of the Amu 

 Darya. June 26. 1899. 



The desert, which lies beyond the riverside thickets of 

 Tamarisks and Phragmites, is limited towards the thicket by 

 a low round hill. The soil is firm, consisting of a kind of 

 loess, but slightly pervious under the surface. The desert is 

 undulating, the soil always the same, but as one proceeds 

 away from the river it becomes more and more covered by 

 gravel or sand. It is noteworthy that this desert poor in 

 sand lies to the west of the Amu Darya: the prevailing nor- 

 therly and northeasterly winds drift the sand into the river 

 which carries it along towards the north. This is why the 

 westiern bank is regularly poorer in sand than the eastern one. 



On the clay-soil there is scattered vegetation of stumpy, 

 shrubby plants about 1 — 3 metres apart on the average. 

 Salsola rigida occurs most frequently as a small bush 

 about 30 centimetres high, densely coated with hairs and dry 

 like a stick. The leaves are cylindrical with central water- 

 storing tissue. Other shrubs present include Lycium rutheni- 

 cum and Calligonum sp. about a foot high. 



The sand occurs in patches which are really low dunes, 

 lowest near the river and becoming higher away from it. 

 The layer of sand very seldom- attains the thickness of 1 



