DISTRIBUTION OF BIRDS IN CEYLON. 25 
difference of level would let in the sea over a broad stretch of 
country on either side of Adam/’s Bridge. 
Our birds of weak flight would then be isolated, and the 
isolation would give an impetus to the formation of local 
peculiar species. 
A considerable period of depression would then have been 
followed by re-elevation and the connection of Ceylon with 
India by a possibly continuous land surface between the 
mainland, Rameswaram, and Mannar. 
The argument for this elevation is supported by the evidence 
of recent marine deposits on the northern coast from Mannar 
round to Trincomalee, so it is by no means geologically 
unsound. 
Ceylon being once more united to India, the more recent 
Carnatic invasion would find its way into our Island, and 
would naturally make its influence most felt at the point of 
entry. 
Have we any evidence to date these successive movements ? 
Of course, it must be understood that I am arguing mainly, if 
not solely, from the distribution of our birds. 
I think a possible clue may be found in the presence of the 
Himalayan element among our birds. 
At the close of the tertiary ages we know that an arctic 
climate prevailed over the northern temperate regions to such 
an extent that the whole of the north of Europe and Asia was 
buried under a great sheet of ice, while beyond the limits of 
this northern ice sheet the Alps and Pyrenees were loaded 
with vast snow fields, from which enormous glaciers descended 
into the plains on either side. 
Evidence of this glacial epoch is also found in the Himalayas. 
The great terminal moraines of the enormous glaciers of this 
period are found in Sikkim at an elevation of 7,000 feet, 
whereas at the present day no glacier in Sikkim descends 
below 14,000 feet.* 
Thus, all over the Northern Hemisphere the temperature 
would have been considerably lower than at present, and 
during the coldest part of the great Ice Age a large portion of 
the Himalayan region must have been covered by snow and 

*Blanford: ‘ Phil. Trans.,”’ loc. cit., p 435. 
4 6(7)14 
