268 



The result we have arrived at does not, therefore, 

 conflict with the theory of the migration of the flora into 

 Transcaspia at the beginning of the quaternary period (see 

 above p. 259). The great number ot endemics moreover 

 confirms ENGLER'S assertion that dry areas (he also mentions 

 "the Asiatic Steppes") whence a great number of plant types 

 are excluded give rise to endemic species 1 ). 



Among the non-endemic species of Transcaspia we 

 distinguish between those which have a northerly, those 

 which have an easterly and those which have a southerly 

 distribution (see above p. 260). 



Northerly distribution is seen in such species as are 

 distributed from Transcaspia over western Siberia and South 

 Russia. The limit is fixed at about 46 N. Lat. (see above 

 p. 262). Of such plants there are 306 or 40 p. cent, of all 

 the species of Transcaspia; in the plant- list they are the 

 species with the letter R included in the distribution-index. 

 This is no small number, but the importance of the figure 

 is lessened when we remember; (1) that with the exception 

 of 29 of the 306 (9 p. cent.), they are equally distributed 

 towards the east and south; (2) that only 96 species (12 

 p. cent, of the total number of species) are common to both 

 Transcaspia and the government of Yekaterinoslaw, (these 

 are indicated in the list by R*). The first of the above 

 points emphasises that the species occurring towards the 

 North are on the whole widely distributed. The 29 species 

 referred to (those indicated in the list merely by R) do not 

 even extend far northwards, only one of them (Erodium 

 Hoefftianum) is found as far north as Yekaterinoslaw. Most 

 of them occur on the Kirghiz steppe which as already stated 

 is very similar to Transcaspia. Nor do many of the remain- 

 ing plants with a northern distribution reach the true steppe 

 or forest areas. 



As regards the second point (2), the number of species 

 common to Transcaspia and Yekaterinoslaw, it may be 

 remarked that, with the exception a few Chenopodiaceae and 

 Lycium and Statice, the species common to both countries 



x ) 1879 p. 10, 1882 p. 50. 



