INTRODUCTORY ESSAY. 229 



The chain of mountains which separates the waters of the 

 Brahmaputra from those of the Irawadi, branches off from 

 this main axis at an acute angle. Its direction is south- 

 west, and it decreases rapidly in elevation after leaving the 

 Mishmi country, forming the Naga hills, which extend from 

 96i° E. long, to the sources of the Cachar and Manipur rivers, 

 and have an average height of 6000 or 7000 feet. Here the 

 chain bifurcates, one branch running due west as far as the 

 great bend of the Brahmaputra, while the other runs nearly due 

 south. The western branch, under the name of the Cachar, 

 Jaintia, Khasia, and Garrow hills, separates the valley of As- 

 sam from that of Silhet. Its elevation varies from 4000 to 

 7000 feet. The other, which separates Cachar, Chittagong, 

 and Aracan, from Ava, has been called the Aeng range ; it is 

 less known, but is in many parts probably equally elevated. 



The provinces of Eastern India selected for botanical divi- 

 sions are — 



1. Mishmi. 6. Aracan. 



2. Assam. 7. Ava and Pegu. 



3. Naga and Khasia. 8. Tenasserim. 



4. Cachar and Silhet. 9. Malayan Peninsula. 



5. Chittagong and Tippera. 



1. Mishmi. 



The country between India and China to the east of Assam 

 is as little known as any other on the globe. Between the 

 British frontier and that of China there are interposed a 

 number of savage tribes, constantly at war, and so extremely 

 jealous of one another that no offers of reward have been suc- 

 cessful in inducing them to guide travellers into the interior 

 of their mountains, though many efforts have been made since 

 Assam was conquered by the Indian Government during the 

 first Burmese war. At that time (as we learn from Captain 

 Wilcox's yerj interesting narrative) a corpa of scientific sur- 

 ^cyors was attached to the army in the field, in order to be 



