oides and Artemisia appear. A little further south Acantholi- 
mon alatavicum appears, Stipa orientalis diminishes in quantity 
and we find large numbers of Oryzopsis molinioides. There 
are single specimens of Silene caucasica and Arenaria Meyeri. 
As the plain forms long flat billows, there is soon a 
stretch parallel to the first, and here again we find Cousinia 
rava and Chrysanthemum pamiricum, but at a new swell of 
the ground they have once more vanished. We now pass 
flat stretches with varying exposures and vegetations. 
N. W. exposure: Scattered Eurolia ceratoides, a few Acan- 
tholimon alatavicum. 
N.E. exposure (decline greater): many Acantholimon ala- 
tavicum and Artemisia, a few Trigonella Emodi and Arenaria 
Meyeri. 
N. W. exposure: Eurotia ceratoides, Cousinia rava, Acan- 
tholimon diapensioides (only a few), Stipa orientalis, Hedysarum 
cephalotes. 
S. W. exposure: Cicer pungens, Cousinia rava, Eurotia 
ceratoides. 
Paying no attention to north and south, but grouping 
the species just mentioned by eastern and western exposures 
we find: western exposure, (the dryest localities), Eurotia 
ceratoides, Cicer pungens; both eastern and western exposures: 
both Acantholimon species, Hedysarum cephalotes, Stipa orien- 
falis and Cousinia rava; eastern exposure alone, (the least dry 
localities); Artemisia, Chrysanthemum pamiricum, Linaria, Tri- 
gonella Emodi, Oryzopsis molinioides, Silene caucasica, Arenaria 
Meyeri. This grouping, in any case the first and last group, 
corresponds to my own observations of the species most resi- 
stant and least resistant to drought. The grouping seems to 
show how the species are assorted in the various associations. 
Under definite conditions, (horizontal plains), the species can 
grow in common, but they are divided into various asso- 
ciations as soon as they are subjected to even a slight degree 
more or less, of the warmth of the sun and attendant moisture. 
The differences discussed here are very small; — the slopes 
are so slight that one cannot feel them when walking. The 
adjustment between the varieties and their surrounding must 
be extraordinarily fine. 
5* 
