— 262 — 
occurring within the territory defined in chap. 1, but also 
species which likewise occur in the Balchash-basin, with 
natural conditions which to my knowledge are almost ident- 
ical with those of Transcaspia and without transition. Dsung- 
aria, on the contrary, is left out, and species which are also 
found there are classed under those with an eastern distri- 
bution (denoted H). In my opinion this was necessary, 
firstly in order to fix a boundary between the eastern and 
the endemic species; secondly because Dsungaria, though 
much the same in character as the Balchash-basin, yet for 
the greater part lies higher and according to BuNGE (1880, 
No. 26) it also differs to some extent in phytogeographical 
respects from the countries lying to the west. 
Nor are plants occurring in the areas north of the Aral 
Sea regarded as endemic. It is impossible to fix any natural 
well-defined boundary between Transcaspia in the south and 
the Kirghiz-steppe in the north, but the boundary I have 
selected, the 46'*® northern parallel of latitude, cannot be far 
wrong as it is confirmed in the recently published work by 
SAWITCH. This memoir shows that several plants which are 
common in Central Europe also occur in the desert north 
of the Aral Sea (see p. 5). 
The census shows that there are 169 endemic species in 
the Transcaspian lowlands, that is 22 p. cent. of the total 
number of species. If the area had been differently defined 
so as to be wider in extent and to include for instance the 
the whole of West-Turkestan inclusive of the mountains, it 
is possible that the endemic percentage might be increased, 
but then it could not be regarded as an expression of, or to 
be connected with, the homogeneous natural conditions which 
pervade and have pervaded the Transcaspian lowlands. Since 
the area has been confined within such narrow limits, we 
must have a certain right to see such a connection, remem- 
bering, however, that the endemism is dependent not only 
on the number of species formed, but also on the faculty of 
migration and adaptation of these species. The endemism 
would have been still greater if the northern boundary of 
our territory had been moved farther north. If the Kirghiz 
steppe and the eastern part of Ciscaucasia to the Jergeni 
