— 30 — 



range (77° E. long., Ferro, ab. GO^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 (SOVa" 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, Polggonaceae {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 Polggonaceae, Nitrarlaceae, Zygophyl- 

 laceae and some species of Tamaricaceae, Papilionaceae and 

 Cruciferae. 



