84 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY , Vol. XV I. 



month. In Ceylon it is quite different ; though I have given above 

 the characteristics of the climate generally it is to be remembered that 

 it is an insular one, and secondary variations are considerable and 

 dependent on very many topical causes. For instance, the rainfall 

 at Colombo is about 75", 120" being the heaviest ever recorded ; 

 whereas at Labugama, only 26 miles off, the rainfall, due no doubt to 

 proximity to the Hills, is no less than 150" or over ; and many other 

 instances throughout the country could be adduced. A comparison of 

 the butterflies from the above two localities would not be likely to 

 show any differences, as the places being so approximate the inter- 

 mixture of individuals would be too great. 



A comparison of the rainfall of the Ceylon Hill district and that 

 of Travancore is exceedingly difficult to make with any degree of 

 accuracy, and I have insufficient data to work on. 



*Mr. H. S. Ferguson has given in his paper on the Birds of Travan- 

 core certain meteorological data, which I have compared with Ceylon 

 statistics. It appears that the rainfall in the Ashambu Hills, which 

 extend from Cape Comorin to 40 miles north with an average altitude 

 of 4,100 feet, have an average rainfall of from 80 to 100 inches ; 

 whereas in Ceylon the average rainfall at a similar altitude is 100 inches 

 and over, and at an approximate altitude of 1,500 feet an average of 

 over 200 inches. 



So far as I can gather from statistics available, it seems clear that the 

 average rainfall in Ceylon is distinctly higher than in corresponds o- 

 districts in Travancore. I have no means of ascertaining whether there 

 is any marked difference in the temperature, but I should say Ceylon 

 undoubtedly is the warmer. It lies further south, and being insular the 

 climate is more equable ; the extensive forest area of Travancore would 

 cause increased evaporation with a lowering of the temperature after 

 heavy rain. I may add that the rainfall of Trevandrum, 50 miles from 

 Cape Comorin, is 65 inches, and that of Colombo, about the same dis- 

 tance south of the Cape, over 75 inches. 



The above considerations, though by no means conclusive, tend to the 

 hypothesis that the heavier rainfall and intenser heat of Ceylon have 

 been the most important agents in producing the depth of colouring 

 which distinguishes the local races of Ceylon butterflies. This naturally 



The Birds of Travancore, by H. S. Ferguson, Jn1.,B<>m.Nat. Hia.'Soc Vol. 15, page 249 



