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The hard and fast line which has restricted the strong 
flying Australasian Cockatoos for ever to the east ofa 
strait of sea only 15 miles wide; is another detail which 
no speculation yet put forth will account for—Bali is the 
western verge of their destribution. 
Mr. Wallace says they are beginning, however, now 
to appear in the next Island, Lombock, 15 miles to the 
west of Bali. But perhaps these are descendants of 
escaped birds, as no doubt the natives cage them. 
If we are invited to exercise of Faith, which seems 
sometimes to approach simplicity, on behalf of Evolution, 
even greater is expected from us on behalf of its reverse; 
the name of the theory Ido not know; Isit ‘Degradation 
by Disuse ?’ 
It is Darwin’s own theory concerning the beetles of 
Madeira, and Mr. Wallace has adopted it for the wingless 
birds of New Zealand, and Mauritius. 
His idea seems to be this, that certain ground- 
feeding birds, not well fitted for long flights, (less fitted 
than our Landrail? which has certainly crossed the 
Atlantic) and existing on ‘land too remote (what is the 
comparative mileage between Mauritius and Africa, 
between England and Norway)? for them to reach the 
nearest shore; had nevertheless contracted the evil habit 
of making the attempt so long as they had any wings left 
todo it with; and consequently perished in the dividing 
sea. 
We are not told why being “far from all land” New 
Zealand was not sufficient land for their necessity, nor is 
this complete annihilation of the theory of instinct to self- 
preservation, which playssuch animportant part in ‘w7zmicry’ 
and other struggles for existence, at all accounted for. 
They were, however, unnaturally prompted to this 
flight from their great island homes, “far from land,” 
