144 THE ZOOLOGIST. 
1. NUMENIUS ARQUATUS. 
2. NUMENIUS ARQUATUS LINEATUS. 
The range of the Common Curlew extends across Europe 
and Asia from the Atlantic to the Pacific: it only reaches the 
Arctic Circle in its western portion under the influence of the 
Gulf Stream, but to the south it includes the whole of the 
Ethiopian and Oriental Regions. To the colder portion of its 
range the Curlew is only a summer visitor. In the British 
Islands it is a resident, but in the Tropics it is only seen during 
winter. 
Asiatic examples are slightly paler in colour, and have, as a 
rule, fewer streaks on the rump, and no bars or dark markings 
on the axillaries, which are snow-white. These characters are 
not very constant, and the two former completely intergrade, 
but, if the Eastern form be regarded as subspecifically distinct, 
it must bear the name of Numenius arquatus lineatus. 
In the basin of the Mediterranean the Curlew is principally 
known as a spring and autumn visitor on migration, but in that 
district a closely-allied, though perfectly distinct, species is a 
resident. The fact that the range of the second species does 
not extend further east than the Ural Mountains confirms the 
theory that the Pale-rumped Curlews escaped from the Polar 
basin when the coming on of the Glacial Period drove them 
south, along the Atlantic shores of Europe. At the height of 
the Glacial Epoch they were probably isolated, in two colonies, 
one in West Africa and the other in the Valley of the Nile, for 
a period long enough to make them specifically distinct. When 
the Glacial Epoch had passed away, the West African colony 
spread over the basin of the Mediterranean, whilst the East 
African colony extended its summer range over the head of its 
ally east and west, until it finally extended from the Atlantic to 
the Pacific, whilst its winter range covered South Africa, and 
afterwards reached India, Burma, and the islands of the Malay 
Archipelago. The complete isolation of the African and Asian 
winter colonies of the Common Curlew produced variation in the 
species, but the uninterrupted area of their distribution in 
summer, combined with the much shorter period during which 
they have been isolated, have prevented the birds from these 
colonies from becoming completely differentiated. 
