president's address. 
121 
which inhabit the Malay Archipelago and Polynesia were specially 
created on the islands where they are now found. There are no 
fewer than seventeen of these species. As no species of Mewl a 
has ever been found in Australia, New Zealand, or any part of the 
Ethiopian region, the presumption is that they came from Eastern 
Asia. The fact that of these seventeen species no island ever 
contains more than one is strong presumptive evidence that they are 
all descended from one original species, or from two or three species 
so imperfectly segregated that when more than one arrived on an 
island they were fertile inter se, like the Golchican and Siberian 
Pheasants, and soon produced a homogeneous race by interbreeding. 
A second conclusion may also be drawn from this fact, — they 
were probably driven from their original homes by some great 
catastrophe which has never occurred since, otherwise it is most 
extraordinary that the descendants of birds which emigrated from 
Eastern Asia to the Eijis and Samoa are now never known to pass 
from one island to another though some of them are within 
sight. 
Eight of these island forms arc dark-headed, five of them are 
pale-headed, whilst four are more uniform in colour. It is therefore 
not an extravagant assumption to suppose that the ancestors were 
two nearly allied species, one with a dark head and one with a 
light head ; and we must also assume that the original home, and 
presumably the centre of their present distribution, were and 
probably continue to be sufficiently far apart to isolate them from 
each other, otherwise they would either have blended in their 
continental home, or have been too widely differentiated from 
each other to have been able to blend in their island home. 
The question is, can we find amongst the Merida# of East Asia 
two species that satisf}' all our requirements ? It seems to me that 
in Merida gouldi and Merida kesslen we have two very closely 
allied continental descendants of the dark-headed ancestor, and in 
Merula castanea and Merida albicincia two still more closely allied 
continental descendants of the pale-lieaded ancestor. 
The two first-mentioned species breed amongst the Ehododendrons 
and the Pines of Eastern Mongolia and Thibet, at an elevation of 
