SPECIES OF THE GENUS NUMENIUS. 147 
wards followed the Siberian coast. Two well-defined species are 
known. 
8. NUMENIUS MINOR. 
The Least Whimbrel probably breeds somewhere on the 
coast of Eastern Siberia, as it is known to pass through Dauria 
and Japan on migration, and winter in Australia. It is very 
closely allied to the Eskimo Whimbrel, but differs from it in 
being slightly smaller, rather longer in the tarsus, and rather 
paler and less barred on the under parts. A more important 
distinction is to be found in the scales at the back of the tarsus, 
which are arranged in hexagonal reticulations in N. borealis, 
but in transverse plates or scutellations in N. minor. 
9. NUMENIUS BOREALIS. 
The Eskimo Curlew, having a distinct pale mesial line on the 
crown, ought to be called the Eskimo Whimbrel. It differs from 
all its congeners, except from its Siberian ally, in having 
scarcely any traces of pale bars on the inner webs of its 
primaries or secondaries. The differences between the two 
species have already been pointed out. 
The Eskimo Whimbrel is essentially an Arctic bird, breeding 
only on the tundras of North America, above the limit of forest 
growth, from Behring Straits to Greenland. It winters in South 
America, where it has occurred as far south as Patagonia. It is 
not known on the Pacific Coast. 
The fifth and last group consists of the Dark-rumped 
Curlews. They may be diagnosed as having the rump pale 
brown, streaked with dark brown, like the mantle and lower 
back; and the crown pale brown, each feather having a dark 
centre. They appear to represent the birds which passed 
through Behring Straits, and followed the American shore 
of the Pacific. Returning north, after the ice had dis- 
appeared, they spread eastward to the Atlantic, whilst a 
party crossed the Behring Sea into Hast Siberia, where they 
became differentiated into a closely allied, but now perfectly 
distinct, species. 
