ON THE OYSTERCATCHERS. 49 
8. Hematopus longirostris. — Probably the same catastrophe 
which drove the Japanese Oystercatcher to the east, an unusually 
late cold spring, induced a second party to start from the winter 
quarters in Ceylon, in order to emigrate in a different direction 
in search of more advantageous breeding grounds, which they 
appear to have found in Australia. The Australian Pied Oyster- 
catcher differs somewhat more from our birds than its Japanese 
ally. Both the eastern birds have light red legs, but the 
Australian species has lost all trace of white on its primaries, 
and the black of the mantle extends some distance on the lower 
back. 
This species is a resident on the coasts of New Zealand, 
Tasmania, and Australia, but does not range further north than 
the southern shores of New Guinea and to other islands imme- 
diately to the north of Australia. 
These three species represent the group of Oystercatchers 
which emigrated along the Atlantic coast of the Old World, and 
may be characterised as having red legs and white rump, as well 
as white lower under parts. 
This completes the list of Oystercatchers, a group of birds 
whose peculiarities of colour and whose geographical distribution 
bear unmistakable evidence of the Glacial Epoch almost as obvious 
as the geological evidence. We can trace almost with certainty 
the routes which the various parties took on their emigration 
from the shores of the Polar basin. The great invasion of 
Europe by Pallas’s Sand Grouse in 1863 is almost the only 
instance of sudden migration which the present generation of 
ornithologists have witnessed, but the gradual extension of the 
breeding areas of many species of birds has been remarked over 
and over again. As regards the Oystercatchers, it seems to me 
that we can almost trace their history from the origin of the 
genus in the small area of the Polar basin, until it has become 
almost cosmopolitan in its range. 
