ANIMAL AND PLANT LIFE. 141 
Kingfishers, but it is conceivable that this periodical flooding 
and drying of these streams initiates a form of migration that 
on a more extended scale, brought about by weather fluctua- 
tions in geological times, might indicate the impulse of 
migration in birds. Thus, reverting to the local migration 
incident to the drying up of large waterways, I noticed on the 
Kumbukkan river that Alcedo ispida, Pelargopsis gurial, and 
Halcyon smyrnensis were plentiful, while not one of these birds 
could be found on the Heda-oya—a river only a few miles to 
the north ; the explanation being that the former stream is 
perennial, and the latter dry in the south-west monsoon. For 
the same reason Ketwpa ceylonensis occurs at tanks that have 
water, and is absent where the opposite is the case. Ketwpa is, 
therefore, to be found along the valley of the Kumbukkan in 
both monsoons, but only in the north-east on the Heda-oya. 
As the time at my disposal was necessarily very limited I 
could do no more than note what was then to be found, so 
that a more studied verification of these observations becomes 
desirable in order to establish proofs of what might be called a 
local migration law. Itis, however, rather striking that species 
of wide general distribution in the wet zone should show an 
erratic distribution in the dry, the key to the explanation 
being possibly found in water distribution. In that direction 
therefore we may anticipate room for the development of a 
definite form of migration, though its range may be com- 
paratively limited. 
I observed in the immediate vicinity of the Kumbukkan 
river that at night numbers of insects were attracted by a 
light, while in the dry country south-east of “* Westminster 
Abbey ” there was a comparative scarcity of what I might call 
lamp-followers. 
At a spot midway between Kebilitte and Ellebubbura I 
had a unique opportunity of observing the effect of scarcity 
of moisture and its influence on insect life. I had seated 
myself under a tree for a few minutes, to rest after a hot 
march of about 15 miles. The jungle all round me appeared 
to be utterly faint with the drought, and I may add that I 
felt much the same myself. I was in a considerable state of 
perspiration, when I noticed a couple of butterflies hovering 
