— 30 — 
range (77° E. long., Ferro, ab. 60° E. long., Greenw.) thus they 
do not overstep that part of the area of Stipa which we have 
termed the Grass-steppe. If these plants occur farther east, 
their limit of uninterrupted distribution is a line generally 
extending towards the north along the western. slopes of 
the Mudgodshar Mts.; from the north end (50'/2° N. lat.) of 
these the line strikes eastwards round the basin in which 
the middle and lower courses of the rivers Irgis, Ulkojak 
and Turgai are situated. They may of course be met with 
as isolated outposts south of this latitude, but never farther 
south than 49° N. lat. 
4. The more southern plant-forms, characteristic both 
for Persia and Aralo-Caspia. do not occur in our flora of 
the present time further north than 47° N. lat. 
5. The more eastern forms, met with in Altaian Siberia 
and Dsungaria, are rarely met with further west than 78 ° 
E. long. F. (ab. 60° W. Greenw.) 
6. In the case of a great many south-eastern forms, 
the lower course of the Syr-Daria (45 °—46° lat.) is the 
northern boundary, and the meridian of the eastern shore 
of the Aral Sea (70° E. long. F., ab. 62° Greenw.) forms the 
western boundary. 
7. The areas east of the Aral sea must be considered 
as the centre of distribution for tree-like forms of the 
families of the Salsolaceae, Polygonaceae (Calligoneae) and 
Papilionaceae. 
8. The flora of the Aralo-Caspian countries as known 
to us at the present time is relatively new in origin, and 
most of its plant-forms have probably distributed themselves 
over these parts of Asia within very recent times; presum- 
ably they came mainly from the east and south, to a less 
degree from west and north, so that from these directions 
they have not penetrated so far. This flora is the gathering 
ground for forms occurring in the steppes of South Russia, 
the Altaian Siberia and Persia. The original plant-forms 
indigenous to the area are evidently limited to: Salso- 
laceae, the tree-like Polygonaceae, Nitrariaceae, Zygophyl- 
laceae and some species of Tamaricaceae, Papilionaceae and 
Cruciferae. 
