pany, ae 
desert, Loess-steppe, Promontory or Stone-steppe, Sand-desert 
and the riverside thickets. 
Of the authors named, Borszczow, as already stated, does 
not use the word formation, and ANTONOW, who uses it, defines 
it as a “natural plant-group’. GRISEBACH's definition of for- 
mation is well known (1838): A group of plants having a 
definite physiognomic character, and characterised by a single 
social species or by several species which although differently 
organised, yet have some feature in common. 
Though there is disagreement between the concept of 
formation held by these authors and the concept maintained 
in the following pages, it is in this case of no vital im- 
portance. In Transcaspia the natural conditions are so uni- 
form, and the boundaries so distinet, at any rate between 
the more important formations (those observed on our first 
railroad journey), that there is very little probability of any 
misunderstanding. 
The formations to be described by us are regarded as 
plant-communities, belonging to certain growth-forms — 
always the same within the same formation — and these 
are determined by and adapted to common conditions. This 
is the same conception as WARMING has (1909 p. 140). On 
practical grounds the conditions of soil will be employed in 
the following descriptions as the principal basis of classifi- 
cation. 
The Transcaspian formations or ‘‘areas’’, described by 
different authors are given in the following table arranged 
in order to show their relationship. In the column to the 
right will be found those formations which I regard as ne- 
cessary for distinction. 
GRISEBACH  BORSZCZOW ANTONOW PAULSEN 
“Territories ” 
| Salt-desert | Sur exert 
aa Loess-desert 
le 
Clay-desert | Loess-steppe | Clay-desert 
Stone-steppe Stone-desert 
Sand-Steppe Moving-sand-desert Sand-desert Sand-desert 
Riverside Thickets Riverside Thickets 
