2 — 
of the fine sand has grains less than 0, mm and some of 
this is smaller than 0,2; mm. The greater mass of the coarse 
sand is between 1 and 0,5 mm in diameter. 
The larger dunes here are very long, but comparatively 
low (2 about to 3 metres) narrow, and crescent-shaped. Their 
direction is about NNE—SSW, with their lee sides towards 
ESE; they must consequently have been formed by winds 
from WNW. The soil between the dunes is sandy also, no 
clay is visible. 
No vegetation is found as a rule on the dunes them- 
selves. Aristida pennata is rather common, but it does not 
grow, or only rarely, on the most shifting, crested dunes. Al- 
hagi Camelorum and the other herbaceous plants prefer still 
calmer places. Nor do the switch-shrubs occur frequently on 
the shifting sand; of these Eremosparton aphyllum, Ammoden- 
dron sp., Smirnowia turkestana, are found as low bushes which 
may attain a height of about a metre. Ammodendron is here 
very thorny (A. Siewersii?). The shrubs are very broad, some 
measuring about 1 metre in diameter. One had become tree- 
like through the lower branches on the stem having been 
killed by some previous sand-drift. 
The most common plant in the desert here is Convolvu- 
lus erinaceus (see p. 94), which at this season shows numerous 
small pink blossoms. It is plentiful everywhere except in the 
deeper valleys and on the tops of the dunes. Its form is a 
leafless, thorny ball. The roots are white and very long. The 
sand has been blown away from many of the plants so 
that they look like small trees with stems which are in real- 
ity the upper rootstocks. If still more sand is blown away, 
the plant falls prostrate on the ground. Thus roots over a 
metre long can be found lying on the surface of the sand 
fixed at one end only, and still having small green shoots. 
Uncovered vertical stems of Alhagi are also seen, dead 
at the end and with new aerial shoots springing from the 
lower, previously buried parts; also buried specimens which 
have formed new aerial shoots from the axillary buds of the 
upper leaves. 
Heliotropium Radula(?) is also common, growing in the 
way already described (see figs. 22, 63). There are rhizomes 
