1G4 D. Praia — List of Diamond Island Plants. [Mat, 



The following papers were read : — 



1. Natural History Notes from U. il/.'s Indian Marine SiirveTj Steamer 

 ** Investigator," Commander Hosktn, R. N. commanding. — No. 17. A 

 List of Biamoyid Island Plants. — By D. Pkain. 



(Abstract.) 

 This paper consisted of an introductory sketch of the vegetation of 

 Diamond Island, off the coast of Arracan, followed by a list of 95 plants 

 collected during a brief visit paid by the writer to the island in November 

 1889. After the list a tabular view of the distribution of the species 

 was presented, the distribution witliin Transgangetic India being sub- 

 divided as follows : — (a) Arracan, Chittagong, Assam ; (5) Pegu, Tenas- 

 serira, Malay Peninsula ; (c) Andamans, Nicobars, Sumatra and Java. 

 This subdivision was found necessary in order to explain the peculiar 

 features of the flora of the island which, owing to the situation, i-epresents 

 very well the area where these three lines of distribution meet and their 

 species intermix. An analytic study of these tables in order to estimate 

 numerically the comparative amounts of the influences of these three 

 adjacent areas concluded the paper. The method adopted consisted in 

 giving the number of species in each of the possible distributional 

 ari'angements within these areas, and using these in succession as 

 numerators ; as denominator in each case the number of areas involved 

 was employed ; the addition of the resultant fractions affecting one area 

 yielded a number that appeared to the writer to be indicative of the 

 proportional influence of each area in the composition of the floi'a of the 

 island. The following results were stated ; the total number of coast 

 species being 20, of inland species being 38. • 



General. 



20 1000 



