- 46 — 



desert, Loess-steppe, Promontory or Stone-steppe, Sand-desert 

 and tlie riverside thickets. 



Of the authors named, Borszczow, as ali-eady 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 distinct, 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 eniployed 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 



"Territories" 

 Salt-desert 



Salt-steppe 



Clay-desert 



Antonow 



Loess-desert 



\ Loess-steppe 

 Stone-steppe 

 Sand-Steppe Moving-sand-desert Sand-desert 



Paulsen 



Salt-desert 



Clay-desert 



Stone-desert 

 Sand-desert 



Riverside Thicliets Riverside Thickets 



