50 NATURAL HISTORY OF 



north-eastern angle with, clusters of islands, successively 

 produced by the deposits, bearing the same aquatic 

 plants. The Tanghi-Deriah, said anciently to have 

 constituted the Deltic branch of the Jaxartes, which 

 discharged its waters into the Caspian, is reported to 

 have been turned off by the Khokanians, who, dreading 

 the Khiva robbers might plant colonies of their own 

 people along the stream, raised a bank to cut off the 

 current. Although great rivers are not to be thus 

 turned from their natural course, the dry bed certainly 

 exists. It is now overgrown with Anabasis ama- 

 dendra* 



The Oxus was stated already, in antiquity, to have 

 changed her course, probably because the bed of the 

 stream shifted repeatedly ; for undeniable vestiges of 

 a broad river course, with upright water-worn banks, 

 occur between Khiva and the Caspian, and notably 

 near Old Ourgengj. Both streams now hasten the re- 

 pletion of the Aral, already of small depth and full of 

 islands ; and these noble rivers, at some future period, 

 may be lost in the sand, or take a course still further 



* We doubt this being the same as the Janderiah, which 

 forsook its bed so late as 1816; Report of a Memoir by 

 M. A. de Kanikoff, to the Geographical Society of London, 

 November, 1844. It is reported by Arabian authors, that 

 both rivers remained dry or seven years, about 460, and 

 the statement is countenanced by the appearance above no- 

 ticed, and perhaps still more,, by the prodigious number of 

 Indo-German and Tahtar invaders, which broke in upon 

 Europe about that period. They could not remain in a land 

 without water. 



