18 INTRODUCTION. 
and D. velutina, to Central Indo-China, the latter extending to Malaya; D. latifolia 
throughout India and in the Malay Peninsula; finally, D. torta, on almost every 
coast. If Western Indo-China and the Eastern Himalaya be treated conjointly, = 
an area where 19 species, of which 4 are endemic, occur. The factor is thus 1%, or 
21, indieating а degree of isolation smaller than that of Malabaria or of Borneo, It 
would appear аз if in the conjoint area of Western Indo-China and the Eastern 
Himalaya we do not have a region that, as regards Dalbergia, is truly natural, but 
that we have rather a region of overflow, where Central Indo-Chinese, South-Western 
Chinese, and Indian influences meet. How far this is true will be more apparent when 
the remaining Indo-Chinese districts are considered, ; 
Central Indo-China, the country between the Irrawaday and the Meinam rivers, is, so 
far as we know, the most important subarea in South-Eastern Asia as regards the number 
of species of Dalbergia, Here we have 21 species—almost as many as in the whole of 
Malaya, fully as many as in Western Indo-China and the Himalaya together, Only 6 of 
them, however, are endemic; these are D. obtusi/olia, D. cultrata, D. glomsrifiora, D. cana, 
D. Kurzii, and Р, Collettii. The endemic factor is thus $y, or 29—a factor much like 
that for Malabaria. Of the distributed species, D. Oliveri, D. Hemslyi, D. cvata, D. 
foliacea go only to Eastern Indo-China; D. fusca to Eastern Indo China and South- 
Western China; D. tamarindifolia to the Philippines, Malaya, South-Western China, Western. 
Indo-China, and the Himalaya; 2, velutina to Malaya and to Western Indo-China;. D. 
parviflora to Malaya, the Moluccas and the Philippines; D, reniformis only to Western 
Indo-China; D. confertiflora to Western Indo-China and the Eastern Himalaya; D. 
stipulacea to Eastern Indo-China, South-Western China, Western Indo-China and the 
Himalaya; D. vəlubilis to Western Indo-China, the Himalaya, and India; D. paniculata 
to India generally and to Eastern Indo-China; D. spinosa to the coasts of Chittagong, 
the Sundribuns, Coromandel, and the Philippines; D. torta nearly to every coast. 
Eastern Indo-China, from the Meinam river to the Chinese Sea, but excluding Tongking, 
has yielded 16 species. No fewer than eight of these—D, cochinchinensis, D. cambodiana, 
D. Pierreana, D. mammosa, D. Duperreana, D. bariensis, D. dongnaiensis, and D. Godefroyi— 
are endemic, so that the endemic factor is 4%, or 50. Besides the almost ubiquitous 
D. tria, the distributed species аге D. ovata, D. foliacza, D, Hemsleyi, and D. Oliveri, which 
go only to Central Indo-China; D. fusca, which goes only to Central Indo-China and 
to South-Western China; D. paniculata, which goes to Central Indo-China and recurs 
in India; finally D. stipulacea, which goes to Central and Western Indo-China, to 
South-Western China and to the Himalaya. The result of uniting Eastern and 
Central Indo-China is to give an area with 29 species, of which 18 are endemic, so 
that the endemic factor is 2$, or 62—a figure much like the factors for China as a 
whole, for Papuasia as a whole, and for Malaya as a whole. 
If the conjoined area of the Eastern Himalaya and Western Indo. 
turn added to the conjoined area of Central and Eastern Indo- 
where there are 40 species, of which 22 are endemie, so th 
3%, or 55. This gives an endemic factor for the whole of Indo-China, lower than the 
sss for Central and Easter п Indo-China taken conjointly ; this suggests that the natural 
affinity of Western Indo-China is less with the country to the east of the Irrawaday 
than with the other adjacent regions, | 
In order to obtain an area with the highest possible endemic faetor, it was 
necessary to separate South-Western China (Yunnan and Western Szechuen) from the 
rest of China. The result was the isolation of Eastern China, including Central China 
China be in 
China, we get a region 
at the endemic factor is 
