1915-16.] BOTANICAL SOCIETY OF EDINBURGH 51 



than a remaiant of the old Sino-Himalayan range between 

 the Himalayas and Kansu, especially as the Salween flows 

 eastwards to begin with, parallel to the Brahmaputra or 

 Tsangpo. Undoubtedly such a communication range does 

 exist. It has recently been shown that the Brahmaputra 

 cuts across the main axis of the Himalayas, and a 

 tremendous peak in the N.E. corner of Assam has been 

 identified as situated on the axis. This is what I should 

 have expected, and I will go further and say that there 

 exists a great range of mountains to the south of the 

 Salween sources, reaching from near the Brahmaputra 

 (which has cut across it) on the west, to the sources of the 

 Irrawaddy (Taron) on the east, where it joins on to, or 

 rather becomes, the Irrawaddy-Salween divide, and that 

 that range, the real Sino-Himalayan range, the westernmost 

 peak of which is the snowy giant referred to above, is the 

 home of the Primula and the Meconopsis, the link between 

 the Himalayas and Yunnan. 



North of this range the Salween sources themselves pro- 

 bably rise in very dry countr3% but the southern slopes at 

 least of the range will receive a copious rainfall, not inferior to 

 that of the Salween-Irrawaddy divide itself, and should have 

 an ideal climate for the development of a rich alpine flora. 



It may be remarked here that the high peak east of the 

 Brahmaputra on the main axis of the Himalayas is well 

 north of the general trend of that range from W.N.W. to 

 E.S.E. : reference to fig. (vii) on p. 34, and to fig. (iii) on 

 p. 35 suggests the reason for this, and is evidence in favour 

 of that theory. 



Finally, we have to consider the valley floras, and the 

 meeting of monsoon (Indo-Malayan) and Chinese floras on 

 that vast meeting-ground, as I have attempted to delineate 

 it, the Burma- Yunnan frontier. 



I have already mentioned that the Mekong-Salween 

 divide must be considered in two parts, separated by the 

 snow massif of Ka'-gur-pw. North of that uplift the flora 

 of the divide is similar to that of the Mekong-Yangtze 

 divide to the east ; south of it, to the flora of the Salween- 

 Irrawaddy divide to the west. The inference, therefore, is 

 that the divide has been peopled partly from the north and 

 partly from the south {i.e. the Indo-Malayan region), though 



